freebsd-dev/module/zfs/zpl_super.c

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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2011, Lawrence Livermore National Security, LLC.
*/
#include <sys/zfs_vfsops.h>
#include <sys/zfs_vnops.h>
#include <sys/zfs_znode.h>
#include <sys/zfs_ctldir.h>
#include <sys/zpl.h>
static struct inode *
zpl_inode_alloc(struct super_block *sb)
{
struct inode *ip;
VERIFY3S(zfs_inode_alloc(sb, &ip), ==, 0);
ip->i_version = 1;
return (ip);
}
static void
zpl_inode_destroy(struct inode *ip)
{
ASSERT(atomic_read(&ip->i_count) == 0);
zfs_inode_destroy(ip);
}
/*
* Called from __mark_inode_dirty() to reflect that something in the
* inode has changed. We use it to ensure the znode system attributes
* are always strictly update to date with respect to the inode.
*/
#ifdef HAVE_DIRTY_INODE_WITH_FLAGS
static void
zpl_dirty_inode(struct inode *ip, int flags)
{
fstrans_cookie_t cookie;
cookie = spl_fstrans_mark();
zfs_dirty_inode(ip, flags);
spl_fstrans_unmark(cookie);
}
#else
static void
zpl_dirty_inode(struct inode *ip)
{
fstrans_cookie_t cookie;
cookie = spl_fstrans_mark();
zfs_dirty_inode(ip, 0);
spl_fstrans_unmark(cookie);
}
#endif /* HAVE_DIRTY_INODE_WITH_FLAGS */
/*
* When ->drop_inode() is called its return value indicates if the
* inode should be evicted from the inode cache. If the inode is
* unhashed and has no links the default policy is to evict it
* immediately.
*
* Prior to 2.6.36 this eviction was accomplished by the vfs calling
* ->delete_inode(). It was ->delete_inode()'s responsibility to
* truncate the inode pages and call clear_inode(). The call to
* clear_inode() synchronously invalidates all the buffers and
* calls ->clear_inode(). It was ->clear_inode()'s responsibility
* to cleanup and filesystem specific data before freeing the inode.
*
* This elaborate mechanism was replaced by ->evict_inode() which
* does the job of both ->delete_inode() and ->clear_inode(). It
* will be called exactly once, and when it returns the inode must
* be in a state where it can simply be freed.i
*
* The ->evict_inode() callback must minimally truncate the inode pages,
* and call clear_inode(). For 2.6.35 and later kernels this will
* simply update the inode state, with the sync occurring before the
* truncate in evict(). For earlier kernels clear_inode() maps to
* end_writeback() which is responsible for completing all outstanding
* write back. In either case, once this is done it is safe to cleanup
* any remaining inode specific data via zfs_inactive().
* remaining filesystem specific data.
*/
#ifdef HAVE_EVICT_INODE
static void
zpl_evict_inode(struct inode *ip)
{
fstrans_cookie_t cookie;
cookie = spl_fstrans_mark();
truncate_setsize(ip, 0);
clear_inode(ip);
zfs_inactive(ip);
spl_fstrans_unmark(cookie);
}
#else
Restructure per-filesystem reclaim Originally when the ARC prune callback was introduced the idea was to register a single callback for the ZPL. The ARC could invoke this call back if it needed the ZPL to drop dentries, inodes, or other cache objects which might be pinning buffers in the ARC. The ZPL would iterate over all ZFS super blocks and perform the reclaim. For the most part this design has worked well but due to limitations in 2.6.35 and earlier kernels there were some problems. This patch is designed to address those issues. 1) iterate_supers_type() is not provided by all kernels which makes it impossible to safely iterate over all zpl_fs_type filesystems in a single callback. The most straight forward and portable way to resolve this is to register a callback per-filesystem during mount. The arc_*_prune_callback() functions have always supported multiple callbacks so this is functionally a very small change. 2) Commit 050d22b removed the non-portable shrink_dcache_memory() and shrink_icache_memory() functions and didn't replace them with equivalent functionality. This meant that for Linux 3.1 and older kernels the ARC had no mechanism to drop dentries and inodes from the caches if needed. This patch adds that missing functionality by calling shrink_dcache_parent() to release dentries which may be pinning inodes. This will result in all unused cache entries being dropped which is a bit heavy handed but it's the only interface available for old kernels. 3) A zpl_drop_inode() callback is registered for kernels older than 2.6.35 which do not support the .evict_inode callback. This ensures that when the last reference on an inode is dropped it is immediately removed from the cache. If this isn't done than inode can end up on the global unused LRU with no mechanism available to ZFS to drop them. Since the ARC buffers are not dropped the hottest inodes can still be recreated without performing disk IO. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Pavel Snajdr <snajpa@snajpa.net> Issue #3160
2015-03-17 22:07:47 +00:00
static void
zpl_drop_inode(struct inode *ip)
{
generic_delete_inode(ip);
}
static void
zpl_clear_inode(struct inode *ip)
{
fstrans_cookie_t cookie;
cookie = spl_fstrans_mark();
zfs_inactive(ip);
spl_fstrans_unmark(cookie);
}
static void
zpl_inode_delete(struct inode *ip)
{
truncate_setsize(ip, 0);
clear_inode(ip);
}
#endif /* HAVE_EVICT_INODE */
static void
zpl_put_super(struct super_block *sb)
{
fstrans_cookie_t cookie;
int error;
cookie = spl_fstrans_mark();
error = -zfs_umount(sb);
spl_fstrans_unmark(cookie);
ASSERT3S(error, <=, 0);
}
static int
zpl_sync_fs(struct super_block *sb, int wait)
{
fstrans_cookie_t cookie;
cred_t *cr = CRED();
int error;
crhold(cr);
cookie = spl_fstrans_mark();
error = -zfs_sync(sb, wait, cr);
spl_fstrans_unmark(cookie);
crfree(cr);
ASSERT3S(error, <=, 0);
return (error);
}
static int
zpl_statfs(struct dentry *dentry, struct kstatfs *statp)
{
fstrans_cookie_t cookie;
int error;
cookie = spl_fstrans_mark();
error = -zfs_statvfs(dentry, statp);
spl_fstrans_unmark(cookie);
ASSERT3S(error, <=, 0);
return (error);
}
enum {
TOKEN_RO,
TOKEN_RW,
TOKEN_SETUID,
TOKEN_NOSETUID,
TOKEN_EXEC,
TOKEN_NOEXEC,
TOKEN_DEVICES,
TOKEN_NODEVICES,
TOKEN_DIRXATTR,
TOKEN_SAXATTR,
TOKEN_XATTR,
TOKEN_NOXATTR,
TOKEN_ATIME,
TOKEN_NOATIME,
TOKEN_RELATIME,
TOKEN_NORELATIME,
TOKEN_NBMAND,
TOKEN_NONBMAND,
TOKEN_MNTPOINT,
TOKEN_LAST,
};
static const match_table_t zpl_tokens = {
{ TOKEN_RO, MNTOPT_RO },
{ TOKEN_RW, MNTOPT_RW },
{ TOKEN_SETUID, MNTOPT_SETUID },
{ TOKEN_NOSETUID, MNTOPT_NOSETUID },
{ TOKEN_EXEC, MNTOPT_EXEC },
{ TOKEN_NOEXEC, MNTOPT_NOEXEC },
{ TOKEN_DEVICES, MNTOPT_DEVICES },
{ TOKEN_NODEVICES, MNTOPT_NODEVICES },
{ TOKEN_DIRXATTR, MNTOPT_DIRXATTR },
{ TOKEN_SAXATTR, MNTOPT_SAXATTR },
{ TOKEN_XATTR, MNTOPT_XATTR },
{ TOKEN_NOXATTR, MNTOPT_NOXATTR },
{ TOKEN_ATIME, MNTOPT_ATIME },
{ TOKEN_NOATIME, MNTOPT_NOATIME },
{ TOKEN_RELATIME, MNTOPT_RELATIME },
{ TOKEN_NORELATIME, MNTOPT_NORELATIME },
{ TOKEN_NBMAND, MNTOPT_NBMAND },
{ TOKEN_NONBMAND, MNTOPT_NONBMAND },
{ TOKEN_MNTPOINT, MNTOPT_MNTPOINT "=%s" },
{ TOKEN_LAST, NULL },
};
static int
zpl_parse_option(char *option, int token, substring_t *args, zfs_mntopts_t *zmo)
{
switch (token) {
case TOKEN_RO:
zmo->z_readonly = B_TRUE;
zmo->z_do_readonly = B_TRUE;
break;
case TOKEN_RW:
zmo->z_readonly = B_FALSE;
zmo->z_do_readonly = B_TRUE;
break;
case TOKEN_SETUID:
zmo->z_setuid = B_TRUE;
zmo->z_do_setuid = B_TRUE;
break;
case TOKEN_NOSETUID:
zmo->z_setuid = B_FALSE;
zmo->z_do_setuid = B_TRUE;
break;
case TOKEN_EXEC:
zmo->z_exec = B_TRUE;
zmo->z_do_exec = B_TRUE;
break;
case TOKEN_NOEXEC:
zmo->z_exec = B_FALSE;
zmo->z_do_exec = B_TRUE;
break;
case TOKEN_DEVICES:
zmo->z_devices = B_TRUE;
zmo->z_do_devices = B_TRUE;
break;
case TOKEN_NODEVICES:
zmo->z_devices = B_FALSE;
zmo->z_do_devices = B_TRUE;
break;
case TOKEN_DIRXATTR:
zmo->z_xattr = ZFS_XATTR_DIR;
zmo->z_do_xattr = B_TRUE;
break;
case TOKEN_SAXATTR:
zmo->z_xattr = ZFS_XATTR_SA;
zmo->z_do_xattr = B_TRUE;
break;
case TOKEN_XATTR:
zmo->z_xattr = ZFS_XATTR_DIR;
zmo->z_do_xattr = B_TRUE;
break;
case TOKEN_NOXATTR:
zmo->z_xattr = ZFS_XATTR_OFF;
zmo->z_do_xattr = B_TRUE;
break;
case TOKEN_ATIME:
zmo->z_atime = B_TRUE;
zmo->z_do_atime = B_TRUE;
break;
case TOKEN_NOATIME:
zmo->z_atime = B_FALSE;
zmo->z_do_atime = B_TRUE;
break;
case TOKEN_RELATIME:
zmo->z_relatime = B_TRUE;
zmo->z_do_relatime = B_TRUE;
break;
case TOKEN_NORELATIME:
zmo->z_relatime = B_FALSE;
zmo->z_do_relatime = B_TRUE;
break;
case TOKEN_NBMAND:
zmo->z_nbmand = B_TRUE;
zmo->z_do_nbmand = B_TRUE;
break;
case TOKEN_NONBMAND:
zmo->z_nbmand = B_FALSE;
zmo->z_do_nbmand = B_TRUE;
break;
case TOKEN_MNTPOINT:
zmo->z_mntpoint = match_strdup(&args[0]);
if (zmo->z_mntpoint == NULL)
return (-ENOMEM);
break;
default:
break;
}
return (0);
}
/*
* Parse the mntopts string storing the results in provided zmo argument.
* If an error occurs the zmo argument will not be modified. The caller
* needs to set isremount when recycling an existing zfs_mntopts_t.
*/
static int
zpl_parse_options(char *osname, char *mntopts, zfs_mntopts_t *zmo,
boolean_t isremount)
{
zfs_mntopts_t *tmp_zmo;
int error;
tmp_zmo = zfs_mntopts_alloc();
tmp_zmo->z_osname = strdup(osname);
if (mntopts) {
substring_t args[MAX_OPT_ARGS];
char *tmp_mntopts, *p, *t;
int token;
t = tmp_mntopts = strdup(mntopts);
while ((p = strsep(&t, ",")) != NULL) {
if (!*p)
continue;
args[0].to = args[0].from = NULL;
token = match_token(p, zpl_tokens, args);
error = zpl_parse_option(p, token, args, tmp_zmo);
if (error) {
zfs_mntopts_free(tmp_zmo);
strfree(tmp_mntopts);
return (error);
}
}
strfree(tmp_mntopts);
}
if (isremount == B_TRUE) {
if (zmo->z_osname)
strfree(zmo->z_osname);
if (zmo->z_mntpoint)
strfree(zmo->z_mntpoint);
} else {
ASSERT3P(zmo->z_osname, ==, NULL);
ASSERT3P(zmo->z_mntpoint, ==, NULL);
}
memcpy(zmo, tmp_zmo, sizeof (zfs_mntopts_t));
kmem_free(tmp_zmo, sizeof (zfs_mntopts_t));
return (0);
}
static int
zpl_remount_fs(struct super_block *sb, int *flags, char *data)
{
zfs_sb_t *zsb = sb->s_fs_info;
fstrans_cookie_t cookie;
int error;
error = zpl_parse_options(zsb->z_mntopts->z_osname, data,
zsb->z_mntopts, B_TRUE);
if (error)
return (error);
cookie = spl_fstrans_mark();
error = -zfs_remount(sb, flags, zsb->z_mntopts);
spl_fstrans_unmark(cookie);
ASSERT3S(error, <=, 0);
return (error);
}
static int
__zpl_show_options(struct seq_file *seq, zfs_sb_t *zsb)
{
seq_printf(seq, ",%s", zsb->z_flags & ZSB_XATTR ? "xattr" : "noxattr");
#ifdef CONFIG_FS_POSIX_ACL
switch (zsb->z_acl_type) {
case ZFS_ACLTYPE_POSIXACL:
seq_puts(seq, ",posixacl");
break;
default:
seq_puts(seq, ",noacl");
break;
}
#endif /* CONFIG_FS_POSIX_ACL */
return (0);
}
#ifdef HAVE_SHOW_OPTIONS_WITH_DENTRY
static int
zpl_show_options(struct seq_file *seq, struct dentry *root)
{
return (__zpl_show_options(seq, root->d_sb->s_fs_info));
}
#else
static int
zpl_show_options(struct seq_file *seq, struct vfsmount *vfsp)
{
return (__zpl_show_options(seq, vfsp->mnt_sb->s_fs_info));
}
#endif /* HAVE_SHOW_OPTIONS_WITH_DENTRY */
static int
zpl_fill_super(struct super_block *sb, void *data, int silent)
{
zfs_mntopts_t *zmo = (zfs_mntopts_t *)data;
fstrans_cookie_t cookie;
int error;
cookie = spl_fstrans_mark();
error = -zfs_domount(sb, zmo, silent);
spl_fstrans_unmark(cookie);
ASSERT3S(error, <=, 0);
return (error);
}
Linux compat 2.6.39: mount_nodev() The .get_sb callback has been replaced by a .mount callback in the file_system_type structure. When using the new interface the caller must now use the mount_nodev() helper. Unfortunately, the new interface no longer passes the vfsmount down to the zfs layers. This poses a problem for the existing implementation because we currently save this pointer in the super block for latter use. It provides our only entry point in to the namespace layer for manipulating certain mount options. This needed to be done originally to allow commands like 'zfs set atime=off tank' to work properly. It also allowed me to keep more of the original Solaris code unmodified. Under Solaris there is a 1-to-1 mapping between a mount point and a file system so this is a fairly natural thing to do. However, under Linux they many be multiple entries in the namespace which reference the same filesystem. Thus keeping a back reference from the filesystem to the namespace is complicated. Rather than introduce some ugly hack to get the vfsmount and continue as before. I'm leveraging this API change to update the ZFS code to do things in a more natural way for Linux. This has the upside that is resolves the compatibility issue for the long term and fixes several other minor bugs which have been reported. This commit updates the code to remove this vfsmount back reference entirely. All modifications to filesystem mount options are now passed in to the kernel via a '-o remount'. This is the expected Linux mechanism and allows the namespace to properly handle any options which apply to it before passing them on to the file system itself. Aside from fixing the compatibility issue, removing the vfsmount has had the benefit of simplifying the code. This change which fairly involved has turned out nicely. Closes #246 Closes #217 Closes #187 Closes #248 Closes #231
2011-05-19 18:44:07 +00:00
#ifdef HAVE_MOUNT_NODEV
static struct dentry *
zpl_mount(struct file_system_type *fs_type, int flags,
const char *osname, void *data)
{
zfs_mntopts_t *zmo = zfs_mntopts_alloc();
int error;
error = zpl_parse_options((char *)osname, (char *)data, zmo, B_FALSE);
if (error) {
zfs_mntopts_free(zmo);
return (ERR_PTR(error));
}
Linux compat 2.6.39: mount_nodev() The .get_sb callback has been replaced by a .mount callback in the file_system_type structure. When using the new interface the caller must now use the mount_nodev() helper. Unfortunately, the new interface no longer passes the vfsmount down to the zfs layers. This poses a problem for the existing implementation because we currently save this pointer in the super block for latter use. It provides our only entry point in to the namespace layer for manipulating certain mount options. This needed to be done originally to allow commands like 'zfs set atime=off tank' to work properly. It also allowed me to keep more of the original Solaris code unmodified. Under Solaris there is a 1-to-1 mapping between a mount point and a file system so this is a fairly natural thing to do. However, under Linux they many be multiple entries in the namespace which reference the same filesystem. Thus keeping a back reference from the filesystem to the namespace is complicated. Rather than introduce some ugly hack to get the vfsmount and continue as before. I'm leveraging this API change to update the ZFS code to do things in a more natural way for Linux. This has the upside that is resolves the compatibility issue for the long term and fixes several other minor bugs which have been reported. This commit updates the code to remove this vfsmount back reference entirely. All modifications to filesystem mount options are now passed in to the kernel via a '-o remount'. This is the expected Linux mechanism and allows the namespace to properly handle any options which apply to it before passing them on to the file system itself. Aside from fixing the compatibility issue, removing the vfsmount has had the benefit of simplifying the code. This change which fairly involved has turned out nicely. Closes #246 Closes #217 Closes #187 Closes #248 Closes #231
2011-05-19 18:44:07 +00:00
return (mount_nodev(fs_type, flags, zmo, zpl_fill_super));
Linux compat 2.6.39: mount_nodev() The .get_sb callback has been replaced by a .mount callback in the file_system_type structure. When using the new interface the caller must now use the mount_nodev() helper. Unfortunately, the new interface no longer passes the vfsmount down to the zfs layers. This poses a problem for the existing implementation because we currently save this pointer in the super block for latter use. It provides our only entry point in to the namespace layer for manipulating certain mount options. This needed to be done originally to allow commands like 'zfs set atime=off tank' to work properly. It also allowed me to keep more of the original Solaris code unmodified. Under Solaris there is a 1-to-1 mapping between a mount point and a file system so this is a fairly natural thing to do. However, under Linux they many be multiple entries in the namespace which reference the same filesystem. Thus keeping a back reference from the filesystem to the namespace is complicated. Rather than introduce some ugly hack to get the vfsmount and continue as before. I'm leveraging this API change to update the ZFS code to do things in a more natural way for Linux. This has the upside that is resolves the compatibility issue for the long term and fixes several other minor bugs which have been reported. This commit updates the code to remove this vfsmount back reference entirely. All modifications to filesystem mount options are now passed in to the kernel via a '-o remount'. This is the expected Linux mechanism and allows the namespace to properly handle any options which apply to it before passing them on to the file system itself. Aside from fixing the compatibility issue, removing the vfsmount has had the benefit of simplifying the code. This change which fairly involved has turned out nicely. Closes #246 Closes #217 Closes #187 Closes #248 Closes #231
2011-05-19 18:44:07 +00:00
}
#else
static int
zpl_get_sb(struct file_system_type *fs_type, int flags,
const char *osname, void *data, struct vfsmount *mnt)
{
zfs_mntopts_t *zmo = zfs_mntopts_alloc();
int error;
error = zpl_parse_options((char *)osname, (char *)data, zmo, B_FALSE);
if (error) {
zfs_mntopts_free(zmo);
return (error);
}
return (get_sb_nodev(fs_type, flags, zmo, zpl_fill_super, mnt));
}
Linux compat 2.6.39: mount_nodev() The .get_sb callback has been replaced by a .mount callback in the file_system_type structure. When using the new interface the caller must now use the mount_nodev() helper. Unfortunately, the new interface no longer passes the vfsmount down to the zfs layers. This poses a problem for the existing implementation because we currently save this pointer in the super block for latter use. It provides our only entry point in to the namespace layer for manipulating certain mount options. This needed to be done originally to allow commands like 'zfs set atime=off tank' to work properly. It also allowed me to keep more of the original Solaris code unmodified. Under Solaris there is a 1-to-1 mapping between a mount point and a file system so this is a fairly natural thing to do. However, under Linux they many be multiple entries in the namespace which reference the same filesystem. Thus keeping a back reference from the filesystem to the namespace is complicated. Rather than introduce some ugly hack to get the vfsmount and continue as before. I'm leveraging this API change to update the ZFS code to do things in a more natural way for Linux. This has the upside that is resolves the compatibility issue for the long term and fixes several other minor bugs which have been reported. This commit updates the code to remove this vfsmount back reference entirely. All modifications to filesystem mount options are now passed in to the kernel via a '-o remount'. This is the expected Linux mechanism and allows the namespace to properly handle any options which apply to it before passing them on to the file system itself. Aside from fixing the compatibility issue, removing the vfsmount has had the benefit of simplifying the code. This change which fairly involved has turned out nicely. Closes #246 Closes #217 Closes #187 Closes #248 Closes #231
2011-05-19 18:44:07 +00:00
#endif /* HAVE_MOUNT_NODEV */
static void
zpl_kill_sb(struct super_block *sb)
{
zfs_preumount(sb);
kill_anon_super(sb);
#ifdef HAVE_S_INSTANCES_LIST_HEAD
sb->s_instances.next = &(zpl_fs_type.fs_supers);
#endif /* HAVE_S_INSTANCES_LIST_HEAD */
}
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
void
Restructure per-filesystem reclaim Originally when the ARC prune callback was introduced the idea was to register a single callback for the ZPL. The ARC could invoke this call back if it needed the ZPL to drop dentries, inodes, or other cache objects which might be pinning buffers in the ARC. The ZPL would iterate over all ZFS super blocks and perform the reclaim. For the most part this design has worked well but due to limitations in 2.6.35 and earlier kernels there were some problems. This patch is designed to address those issues. 1) iterate_supers_type() is not provided by all kernels which makes it impossible to safely iterate over all zpl_fs_type filesystems in a single callback. The most straight forward and portable way to resolve this is to register a callback per-filesystem during mount. The arc_*_prune_callback() functions have always supported multiple callbacks so this is functionally a very small change. 2) Commit 050d22b removed the non-portable shrink_dcache_memory() and shrink_icache_memory() functions and didn't replace them with equivalent functionality. This meant that for Linux 3.1 and older kernels the ARC had no mechanism to drop dentries and inodes from the caches if needed. This patch adds that missing functionality by calling shrink_dcache_parent() to release dentries which may be pinning inodes. This will result in all unused cache entries being dropped which is a bit heavy handed but it's the only interface available for old kernels. 3) A zpl_drop_inode() callback is registered for kernels older than 2.6.35 which do not support the .evict_inode callback. This ensures that when the last reference on an inode is dropped it is immediately removed from the cache. If this isn't done than inode can end up on the global unused LRU with no mechanism available to ZFS to drop them. Since the ARC buffers are not dropped the hottest inodes can still be recreated without performing disk IO. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Pavel Snajdr <snajpa@snajpa.net> Issue #3160
2015-03-17 22:07:47 +00:00
zpl_prune_sb(int64_t nr_to_scan, void *arg)
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
{
Restructure per-filesystem reclaim Originally when the ARC prune callback was introduced the idea was to register a single callback for the ZPL. The ARC could invoke this call back if it needed the ZPL to drop dentries, inodes, or other cache objects which might be pinning buffers in the ARC. The ZPL would iterate over all ZFS super blocks and perform the reclaim. For the most part this design has worked well but due to limitations in 2.6.35 and earlier kernels there were some problems. This patch is designed to address those issues. 1) iterate_supers_type() is not provided by all kernels which makes it impossible to safely iterate over all zpl_fs_type filesystems in a single callback. The most straight forward and portable way to resolve this is to register a callback per-filesystem during mount. The arc_*_prune_callback() functions have always supported multiple callbacks so this is functionally a very small change. 2) Commit 050d22b removed the non-portable shrink_dcache_memory() and shrink_icache_memory() functions and didn't replace them with equivalent functionality. This meant that for Linux 3.1 and older kernels the ARC had no mechanism to drop dentries and inodes from the caches if needed. This patch adds that missing functionality by calling shrink_dcache_parent() to release dentries which may be pinning inodes. This will result in all unused cache entries being dropped which is a bit heavy handed but it's the only interface available for old kernels. 3) A zpl_drop_inode() callback is registered for kernels older than 2.6.35 which do not support the .evict_inode callback. This ensures that when the last reference on an inode is dropped it is immediately removed from the cache. If this isn't done than inode can end up on the global unused LRU with no mechanism available to ZFS to drop them. Since the ARC buffers are not dropped the hottest inodes can still be recreated without performing disk IO. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Pavel Snajdr <snajpa@snajpa.net> Issue #3160
2015-03-17 22:07:47 +00:00
struct super_block *sb = (struct super_block *)arg;
int objects = 0;
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
Restructure per-filesystem reclaim Originally when the ARC prune callback was introduced the idea was to register a single callback for the ZPL. The ARC could invoke this call back if it needed the ZPL to drop dentries, inodes, or other cache objects which might be pinning buffers in the ARC. The ZPL would iterate over all ZFS super blocks and perform the reclaim. For the most part this design has worked well but due to limitations in 2.6.35 and earlier kernels there were some problems. This patch is designed to address those issues. 1) iterate_supers_type() is not provided by all kernels which makes it impossible to safely iterate over all zpl_fs_type filesystems in a single callback. The most straight forward and portable way to resolve this is to register a callback per-filesystem during mount. The arc_*_prune_callback() functions have always supported multiple callbacks so this is functionally a very small change. 2) Commit 050d22b removed the non-portable shrink_dcache_memory() and shrink_icache_memory() functions and didn't replace them with equivalent functionality. This meant that for Linux 3.1 and older kernels the ARC had no mechanism to drop dentries and inodes from the caches if needed. This patch adds that missing functionality by calling shrink_dcache_parent() to release dentries which may be pinning inodes. This will result in all unused cache entries being dropped which is a bit heavy handed but it's the only interface available for old kernels. 3) A zpl_drop_inode() callback is registered for kernels older than 2.6.35 which do not support the .evict_inode callback. This ensures that when the last reference on an inode is dropped it is immediately removed from the cache. If this isn't done than inode can end up on the global unused LRU with no mechanism available to ZFS to drop them. Since the ARC buffers are not dropped the hottest inodes can still be recreated without performing disk IO. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Pavel Snajdr <snajpa@snajpa.net> Issue #3160
2015-03-17 22:07:47 +00:00
(void) -zfs_sb_prune(sb, nr_to_scan, &objects);
}
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
#ifdef HAVE_NR_CACHED_OBJECTS
static int
zpl_nr_cached_objects(struct super_block *sb)
{
return (0);
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
}
#endif /* HAVE_NR_CACHED_OBJECTS */
#ifdef HAVE_FREE_CACHED_OBJECTS
static void
zpl_free_cached_objects(struct super_block *sb, int nr_to_scan)
{
/* noop */
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
}
#endif /* HAVE_FREE_CACHED_OBJECTS */
const struct super_operations zpl_super_operations = {
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
.alloc_inode = zpl_inode_alloc,
.destroy_inode = zpl_inode_destroy,
.dirty_inode = zpl_dirty_inode,
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
.write_inode = NULL,
#ifdef HAVE_EVICT_INODE
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
.evict_inode = zpl_evict_inode,
#else
Restructure per-filesystem reclaim Originally when the ARC prune callback was introduced the idea was to register a single callback for the ZPL. The ARC could invoke this call back if it needed the ZPL to drop dentries, inodes, or other cache objects which might be pinning buffers in the ARC. The ZPL would iterate over all ZFS super blocks and perform the reclaim. For the most part this design has worked well but due to limitations in 2.6.35 and earlier kernels there were some problems. This patch is designed to address those issues. 1) iterate_supers_type() is not provided by all kernels which makes it impossible to safely iterate over all zpl_fs_type filesystems in a single callback. The most straight forward and portable way to resolve this is to register a callback per-filesystem during mount. The arc_*_prune_callback() functions have always supported multiple callbacks so this is functionally a very small change. 2) Commit 050d22b removed the non-portable shrink_dcache_memory() and shrink_icache_memory() functions and didn't replace them with equivalent functionality. This meant that for Linux 3.1 and older kernels the ARC had no mechanism to drop dentries and inodes from the caches if needed. This patch adds that missing functionality by calling shrink_dcache_parent() to release dentries which may be pinning inodes. This will result in all unused cache entries being dropped which is a bit heavy handed but it's the only interface available for old kernels. 3) A zpl_drop_inode() callback is registered for kernels older than 2.6.35 which do not support the .evict_inode callback. This ensures that when the last reference on an inode is dropped it is immediately removed from the cache. If this isn't done than inode can end up on the global unused LRU with no mechanism available to ZFS to drop them. Since the ARC buffers are not dropped the hottest inodes can still be recreated without performing disk IO. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Pavel Snajdr <snajpa@snajpa.net> Issue #3160
2015-03-17 22:07:47 +00:00
.drop_inode = zpl_drop_inode,
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
.clear_inode = zpl_clear_inode,
.delete_inode = zpl_inode_delete,
#endif /* HAVE_EVICT_INODE */
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
.put_super = zpl_put_super,
.sync_fs = zpl_sync_fs,
.statfs = zpl_statfs,
.remount_fs = zpl_remount_fs,
.show_options = zpl_show_options,
.show_stats = NULL,
#ifdef HAVE_NR_CACHED_OBJECTS
.nr_cached_objects = zpl_nr_cached_objects,
#endif /* HAVE_NR_CACHED_OBJECTS */
#ifdef HAVE_FREE_CACHED_OBJECTS
.free_cached_objects = zpl_free_cached_objects,
#endif /* HAVE_FREE_CACHED_OBJECTS */
};
struct file_system_type zpl_fs_type = {
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
.owner = THIS_MODULE,
.name = ZFS_DRIVER,
Linux compat 2.6.39: mount_nodev() The .get_sb callback has been replaced by a .mount callback in the file_system_type structure. When using the new interface the caller must now use the mount_nodev() helper. Unfortunately, the new interface no longer passes the vfsmount down to the zfs layers. This poses a problem for the existing implementation because we currently save this pointer in the super block for latter use. It provides our only entry point in to the namespace layer for manipulating certain mount options. This needed to be done originally to allow commands like 'zfs set atime=off tank' to work properly. It also allowed me to keep more of the original Solaris code unmodified. Under Solaris there is a 1-to-1 mapping between a mount point and a file system so this is a fairly natural thing to do. However, under Linux they many be multiple entries in the namespace which reference the same filesystem. Thus keeping a back reference from the filesystem to the namespace is complicated. Rather than introduce some ugly hack to get the vfsmount and continue as before. I'm leveraging this API change to update the ZFS code to do things in a more natural way for Linux. This has the upside that is resolves the compatibility issue for the long term and fixes several other minor bugs which have been reported. This commit updates the code to remove this vfsmount back reference entirely. All modifications to filesystem mount options are now passed in to the kernel via a '-o remount'. This is the expected Linux mechanism and allows the namespace to properly handle any options which apply to it before passing them on to the file system itself. Aside from fixing the compatibility issue, removing the vfsmount has had the benefit of simplifying the code. This change which fairly involved has turned out nicely. Closes #246 Closes #217 Closes #187 Closes #248 Closes #231
2011-05-19 18:44:07 +00:00
#ifdef HAVE_MOUNT_NODEV
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
.mount = zpl_mount,
Linux compat 2.6.39: mount_nodev() The .get_sb callback has been replaced by a .mount callback in the file_system_type structure. When using the new interface the caller must now use the mount_nodev() helper. Unfortunately, the new interface no longer passes the vfsmount down to the zfs layers. This poses a problem for the existing implementation because we currently save this pointer in the super block for latter use. It provides our only entry point in to the namespace layer for manipulating certain mount options. This needed to be done originally to allow commands like 'zfs set atime=off tank' to work properly. It also allowed me to keep more of the original Solaris code unmodified. Under Solaris there is a 1-to-1 mapping between a mount point and a file system so this is a fairly natural thing to do. However, under Linux they many be multiple entries in the namespace which reference the same filesystem. Thus keeping a back reference from the filesystem to the namespace is complicated. Rather than introduce some ugly hack to get the vfsmount and continue as before. I'm leveraging this API change to update the ZFS code to do things in a more natural way for Linux. This has the upside that is resolves the compatibility issue for the long term and fixes several other minor bugs which have been reported. This commit updates the code to remove this vfsmount back reference entirely. All modifications to filesystem mount options are now passed in to the kernel via a '-o remount'. This is the expected Linux mechanism and allows the namespace to properly handle any options which apply to it before passing them on to the file system itself. Aside from fixing the compatibility issue, removing the vfsmount has had the benefit of simplifying the code. This change which fairly involved has turned out nicely. Closes #246 Closes #217 Closes #187 Closes #248 Closes #231
2011-05-19 18:44:07 +00:00
#else
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
.get_sb = zpl_get_sb,
Linux compat 2.6.39: mount_nodev() The .get_sb callback has been replaced by a .mount callback in the file_system_type structure. When using the new interface the caller must now use the mount_nodev() helper. Unfortunately, the new interface no longer passes the vfsmount down to the zfs layers. This poses a problem for the existing implementation because we currently save this pointer in the super block for latter use. It provides our only entry point in to the namespace layer for manipulating certain mount options. This needed to be done originally to allow commands like 'zfs set atime=off tank' to work properly. It also allowed me to keep more of the original Solaris code unmodified. Under Solaris there is a 1-to-1 mapping between a mount point and a file system so this is a fairly natural thing to do. However, under Linux they many be multiple entries in the namespace which reference the same filesystem. Thus keeping a back reference from the filesystem to the namespace is complicated. Rather than introduce some ugly hack to get the vfsmount and continue as before. I'm leveraging this API change to update the ZFS code to do things in a more natural way for Linux. This has the upside that is resolves the compatibility issue for the long term and fixes several other minor bugs which have been reported. This commit updates the code to remove this vfsmount back reference entirely. All modifications to filesystem mount options are now passed in to the kernel via a '-o remount'. This is the expected Linux mechanism and allows the namespace to properly handle any options which apply to it before passing them on to the file system itself. Aside from fixing the compatibility issue, removing the vfsmount has had the benefit of simplifying the code. This change which fairly involved has turned out nicely. Closes #246 Closes #217 Closes #187 Closes #248 Closes #231
2011-05-19 18:44:07 +00:00
#endif /* HAVE_MOUNT_NODEV */
Linux 3.1 compat, super_block->s_shrink The Linux 3.1 kernel has introduced the concept of per-filesystem shrinkers which are directly assoicated with a super block. Prior to this change there was one shared global shrinker. The zfs code relied on being able to call the global shrinker when the arc_meta_limit was exceeded. This would cause the VFS to drop references on a fraction of the dentries in the dcache. The ARC could then safely reclaim the memory used by these entries and honor the arc_meta_limit. Unfortunately, when per-filesystem shrinkers were added the old interfaces were made unavailable. This change adds support to use the new per-filesystem shrinker interface so we can continue to honor the arc_meta_limit. The major benefit of the new interface is that we can now target only the zfs filesystem for dentry and inode pruning. Thus we can minimize any impact on the caching of other filesystems. In the context of making this change several other important issues related to managing the ARC were addressed, they include: * The dnlc_reduce_cache() function which was called by the ARC to drop dentries for the Posix layer was replaced with a generic zfs_prune_t callback. The ZPL layer now registers a callback to drop these dentries removing a layering violation which dates back to the Solaris code. This callback can also be used by other ARC consumers such as Lustre. arc_add_prune_callback() arc_remove_prune_callback() * The arc_reduce_dnlc_percent module option has been changed to arc_meta_prune for clarity. The dnlc functions are specific to Solaris's VFS and have already been largely eliminated already. The replacement tunable now represents the number of bytes the prune callback will request when invoked. * Less aggressively invoke the prune callback. We used to call this whenever we exceeded the arc_meta_limit however that's not strictly correct since it results in over zeleous reclaim of dentries and inodes. It is now only called once the arc_meta_limit is exceeded and every effort has been made to evict other data from the ARC cache. * More promptly manage exceeding the arc_meta_limit. When reading meta data in to the cache if a buffer was unable to be recycled notify the arc_reclaim thread to invoke the required prune. * Added arcstat_prune kstat which is incremented when the ARC is forced to request that a consumer prune its cache. Remember this will only occur when the ARC has no other choice. If it can evict buffers safely without invoking the prune callback it will. * This change is also expected to resolve the unexpect collapses of the ARC cache. This would occur because when exceeded just the arc_meta_limit reclaim presure would be excerted on the arc_c value via arc_shrink(). This effectively shrunk the entire cache when really we just needed to reclaim meta data. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #466 Closes #292
2011-12-22 20:20:43 +00:00
.kill_sb = zpl_kill_sb,
};