freebsd-nq/module/zfs/zpl_file.c
Brian Behlendorf 1efdc45ea8 Fix O_APPEND open(2) flag
As described in flags section of open(2):

  O_APPEND:
    The  file  is  opened in append mode.  Before each write(2), the
    file offset is positioned at the end of the  file,  as  if  with
    lseek(2).   O_APPEND may lead to corrupted files on NFS filesys-
    tems if more than one process appends data to a  file  at  once.
    This is because NFS does not support appending to a file, so the
    client kernel has to simulate it, which can't be done without  a
    race condition.

This issue was originally overlooked because normally the generic
VFS code handles this for a filesystem.  However, because ZFS explictly
registers a zpl_write() function it's responsible for the seek.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3124
2015-02-24 11:21:54 -08:00

769 lines
20 KiB
C

/*
* 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/dmu_objset.h>
#include <sys/zfs_vfsops.h>
#include <sys/zfs_vnops.h>
#include <sys/zfs_znode.h>
#include <sys/zpl.h>
static int
zpl_open(struct inode *ip, struct file *filp)
{
cred_t *cr = CRED();
int error;
error = generic_file_open(ip, filp);
if (error)
return (error);
crhold(cr);
error = -zfs_open(ip, filp->f_mode, filp->f_flags, cr);
crfree(cr);
ASSERT3S(error, <=, 0);
return (error);
}
static int
zpl_release(struct inode *ip, struct file *filp)
{
cred_t *cr = CRED();
int error;
if (ITOZ(ip)->z_atime_dirty)
zfs_mark_inode_dirty(ip);
crhold(cr);
error = -zfs_close(ip, filp->f_flags, cr);
crfree(cr);
ASSERT3S(error, <=, 0);
return (error);
}
static int
zpl_iterate(struct file *filp, struct dir_context *ctx)
{
struct dentry *dentry = filp->f_path.dentry;
cred_t *cr = CRED();
int error;
crhold(cr);
error = -zfs_readdir(dentry->d_inode, ctx, cr);
crfree(cr);
ASSERT3S(error, <=, 0);
return (error);
}
#if !defined(HAVE_VFS_ITERATE)
static int
zpl_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
struct dir_context ctx = DIR_CONTEXT_INIT(dirent, filldir, filp->f_pos);
int error;
error = zpl_iterate(filp, &ctx);
filp->f_pos = ctx.pos;
return (error);
}
#endif /* HAVE_VFS_ITERATE */
#if defined(HAVE_FSYNC_WITH_DENTRY)
/*
* Linux 2.6.x - 2.6.34 API,
* Through 2.6.34 the nfsd kernel server would pass a NULL 'file struct *'
* to the fops->fsync() hook. For this reason, we must be careful not to
* use filp unconditionally.
*/
static int
zpl_fsync(struct file *filp, struct dentry *dentry, int datasync)
{
cred_t *cr = CRED();
int error;
crhold(cr);
error = -zfs_fsync(dentry->d_inode, datasync, cr);
crfree(cr);
ASSERT3S(error, <=, 0);
return (error);
}
static int
zpl_aio_fsync(struct kiocb *kiocb, int datasync)
{
struct file *filp = kiocb->ki_filp;
return (zpl_fsync(filp, filp->f_path.dentry, datasync));
}
#elif defined(HAVE_FSYNC_WITHOUT_DENTRY)
/*
* Linux 2.6.35 - 3.0 API,
* As of 2.6.35 the dentry argument to the fops->fsync() hook was deemed
* redundant. The dentry is still accessible via filp->f_path.dentry,
* and we are guaranteed that filp will never be NULL.
*/
static int
zpl_fsync(struct file *filp, int datasync)
{
struct inode *inode = filp->f_mapping->host;
cred_t *cr = CRED();
int error;
crhold(cr);
error = -zfs_fsync(inode, datasync, cr);
crfree(cr);
ASSERT3S(error, <=, 0);
return (error);
}
static int
zpl_aio_fsync(struct kiocb *kiocb, int datasync)
{
return (zpl_fsync(kiocb->ki_filp, datasync));
}
#elif defined(HAVE_FSYNC_RANGE)
/*
* Linux 3.1 - 3.x API,
* As of 3.1 the responsibility to call filemap_write_and_wait_range() has
* been pushed down in to the .fsync() vfs hook. Additionally, the i_mutex
* lock is no longer held by the caller, for zfs we don't require the lock
* to be held so we don't acquire it.
*/
static int
zpl_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
{
struct inode *inode = filp->f_mapping->host;
cred_t *cr = CRED();
int error;
error = filemap_write_and_wait_range(inode->i_mapping, start, end);
if (error)
return (error);
crhold(cr);
error = -zfs_fsync(inode, datasync, cr);
crfree(cr);
ASSERT3S(error, <=, 0);
return (error);
}
static int
zpl_aio_fsync(struct kiocb *kiocb, int datasync)
{
return (zpl_fsync(kiocb->ki_filp, kiocb->ki_pos,
kiocb->ki_pos + kiocb->ki_nbytes, datasync));
}
#else
#error "Unsupported fops->fsync() implementation"
#endif
static inline ssize_t
zpl_read_common_iovec(struct inode *ip, const struct iovec *iovp, size_t count,
unsigned long nr_segs, loff_t *ppos, uio_seg_t segment,
int flags, cred_t *cr)
{
ssize_t read;
uio_t uio;
int error;
uio.uio_iov = (struct iovec *)iovp;
uio.uio_resid = count;
uio.uio_iovcnt = nr_segs;
uio.uio_loffset = *ppos;
uio.uio_limit = MAXOFFSET_T;
uio.uio_segflg = segment;
error = -zfs_read(ip, &uio, flags, cr);
if (error < 0)
return (error);
read = count - uio.uio_resid;
*ppos += read;
task_io_account_read(read);
return (read);
}
inline ssize_t
zpl_read_common(struct inode *ip, const char *buf, size_t len, loff_t *ppos,
uio_seg_t segment, int flags, cred_t *cr)
{
struct iovec iov;
iov.iov_base = (void *)buf;
iov.iov_len = len;
return (zpl_read_common_iovec(ip, &iov, len, 1, ppos, segment,
flags, cr));
}
static ssize_t
zpl_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
{
cred_t *cr = CRED();
ssize_t read;
crhold(cr);
read = zpl_read_common(filp->f_mapping->host, buf, len, ppos,
UIO_USERSPACE, filp->f_flags, cr);
crfree(cr);
return (read);
}
static ssize_t
zpl_aio_read(struct kiocb *kiocb, const struct iovec *iovp,
unsigned long nr_segs, loff_t pos)
{
cred_t *cr = CRED();
struct file *filp = kiocb->ki_filp;
size_t count = kiocb->ki_nbytes;
ssize_t read;
size_t alloc_size = sizeof (struct iovec) * nr_segs;
struct iovec *iov_tmp = kmem_alloc(alloc_size, KM_SLEEP);
bcopy(iovp, iov_tmp, alloc_size);
ASSERT(iovp);
crhold(cr);
read = zpl_read_common_iovec(filp->f_mapping->host, iov_tmp, count,
nr_segs, &kiocb->ki_pos, UIO_USERSPACE, filp->f_flags, cr);
crfree(cr);
kmem_free(iov_tmp, alloc_size);
return (read);
}
static inline ssize_t
zpl_write_common_iovec(struct inode *ip, const struct iovec *iovp, size_t count,
unsigned long nr_segs, loff_t *ppos, uio_seg_t segment,
int flags, cred_t *cr)
{
ssize_t wrote;
uio_t uio;
int error;
if (flags & O_APPEND)
*ppos = i_size_read(ip);
uio.uio_iov = (struct iovec *)iovp;
uio.uio_resid = count;
uio.uio_iovcnt = nr_segs;
uio.uio_loffset = *ppos;
uio.uio_limit = MAXOFFSET_T;
uio.uio_segflg = segment;
error = -zfs_write(ip, &uio, flags, cr);
if (error < 0)
return (error);
wrote = count - uio.uio_resid;
*ppos += wrote;
task_io_account_write(wrote);
return (wrote);
}
inline ssize_t
zpl_write_common(struct inode *ip, const char *buf, size_t len, loff_t *ppos,
uio_seg_t segment, int flags, cred_t *cr)
{
struct iovec iov;
iov.iov_base = (void *)buf;
iov.iov_len = len;
return (zpl_write_common_iovec(ip, &iov, len, 1, ppos, segment,
flags, cr));
}
static ssize_t
zpl_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
{
cred_t *cr = CRED();
ssize_t wrote;
crhold(cr);
wrote = zpl_write_common(filp->f_mapping->host, buf, len, ppos,
UIO_USERSPACE, filp->f_flags, cr);
crfree(cr);
return (wrote);
}
static ssize_t
zpl_aio_write(struct kiocb *kiocb, const struct iovec *iovp,
unsigned long nr_segs, loff_t pos)
{
cred_t *cr = CRED();
struct file *filp = kiocb->ki_filp;
size_t count = kiocb->ki_nbytes;
ssize_t wrote;
size_t alloc_size = sizeof (struct iovec) * nr_segs;
struct iovec *iov_tmp = kmem_alloc(alloc_size, KM_SLEEP);
bcopy(iovp, iov_tmp, alloc_size);
ASSERT(iovp);
crhold(cr);
wrote = zpl_write_common_iovec(filp->f_mapping->host, iov_tmp, count,
nr_segs, &kiocb->ki_pos, UIO_USERSPACE, filp->f_flags, cr);
crfree(cr);
kmem_free(iov_tmp, alloc_size);
return (wrote);
}
static loff_t
zpl_llseek(struct file *filp, loff_t offset, int whence)
{
#if defined(SEEK_HOLE) && defined(SEEK_DATA)
if (whence == SEEK_DATA || whence == SEEK_HOLE) {
struct inode *ip = filp->f_mapping->host;
loff_t maxbytes = ip->i_sb->s_maxbytes;
loff_t error;
spl_inode_lock(ip);
error = -zfs_holey(ip, whence, &offset);
if (error == 0)
error = lseek_execute(filp, ip, offset, maxbytes);
spl_inode_unlock(ip);
return (error);
}
#endif /* SEEK_HOLE && SEEK_DATA */
return (generic_file_llseek(filp, offset, whence));
}
/*
* It's worth taking a moment to describe how mmap is implemented
* for zfs because it differs considerably from other Linux filesystems.
* However, this issue is handled the same way under OpenSolaris.
*
* The issue is that by design zfs bypasses the Linux page cache and
* leaves all caching up to the ARC. This has been shown to work
* well for the common read(2)/write(2) case. However, mmap(2)
* is problem because it relies on being tightly integrated with the
* page cache. To handle this we cache mmap'ed files twice, once in
* the ARC and a second time in the page cache. The code is careful
* to keep both copies synchronized.
*
* When a file with an mmap'ed region is written to using write(2)
* both the data in the ARC and existing pages in the page cache
* are updated. For a read(2) data will be read first from the page
* cache then the ARC if needed. Neither a write(2) or read(2) will
* will ever result in new pages being added to the page cache.
*
* New pages are added to the page cache only via .readpage() which
* is called when the vfs needs to read a page off disk to back the
* virtual memory region. These pages may be modified without
* notifying the ARC and will be written out periodically via
* .writepage(). This will occur due to either a sync or the usual
* page aging behavior. Note because a read(2) of a mmap'ed file
* will always check the page cache first even when the ARC is out
* of date correct data will still be returned.
*
* While this implementation ensures correct behavior it does have
* have some drawbacks. The most obvious of which is that it
* increases the required memory footprint when access mmap'ed
* files. It also adds additional complexity to the code keeping
* both caches synchronized.
*
* Longer term it may be possible to cleanly resolve this wart by
* mapping page cache pages directly on to the ARC buffers. The
* Linux address space operations are flexible enough to allow
* selection of which pages back a particular index. The trick
* would be working out the details of which subsystem is in
* charge, the ARC, the page cache, or both. It may also prove
* helpful to move the ARC buffers to a scatter-gather lists
* rather than a vmalloc'ed region.
*/
static int
zpl_mmap(struct file *filp, struct vm_area_struct *vma)
{
struct inode *ip = filp->f_mapping->host;
znode_t *zp = ITOZ(ip);
int error;
error = -zfs_map(ip, vma->vm_pgoff, (caddr_t *)vma->vm_start,
(size_t)(vma->vm_end - vma->vm_start), vma->vm_flags);
if (error)
return (error);
error = generic_file_mmap(filp, vma);
if (error)
return (error);
mutex_enter(&zp->z_lock);
zp->z_is_mapped = 1;
mutex_exit(&zp->z_lock);
return (error);
}
/*
* Populate a page with data for the Linux page cache. This function is
* only used to support mmap(2). There will be an identical copy of the
* data in the ARC which is kept up to date via .write() and .writepage().
*
* Current this function relies on zpl_read_common() and the O_DIRECT
* flag to read in a page. This works but the more correct way is to
* update zfs_fillpage() to be Linux friendly and use that interface.
*/
static int
zpl_readpage(struct file *filp, struct page *pp)
{
struct inode *ip;
struct page *pl[1];
int error = 0;
ASSERT(PageLocked(pp));
ip = pp->mapping->host;
pl[0] = pp;
error = -zfs_getpage(ip, pl, 1);
if (error) {
SetPageError(pp);
ClearPageUptodate(pp);
} else {
ClearPageError(pp);
SetPageUptodate(pp);
flush_dcache_page(pp);
}
unlock_page(pp);
return (error);
}
/*
* Populate a set of pages with data for the Linux page cache. This
* function will only be called for read ahead and never for demand
* paging. For simplicity, the code relies on read_cache_pages() to
* correctly lock each page for IO and call zpl_readpage().
*/
static int
zpl_readpages(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
return (read_cache_pages(mapping, pages,
(filler_t *)zpl_readpage, filp));
}
int
zpl_putpage(struct page *pp, struct writeback_control *wbc, void *data)
{
struct address_space *mapping = data;
fstrans_cookie_t cookie;
ASSERT(PageLocked(pp));
ASSERT(!PageWriteback(pp));
cookie = spl_fstrans_mark();
(void) zfs_putpage(mapping->host, pp, wbc);
spl_fstrans_unmark(cookie);
return (0);
}
static int
zpl_writepages(struct address_space *mapping, struct writeback_control *wbc)
{
znode_t *zp = ITOZ(mapping->host);
zfs_sb_t *zsb = ITOZSB(mapping->host);
enum writeback_sync_modes sync_mode;
int result;
ZFS_ENTER(zsb);
if (zsb->z_os->os_sync == ZFS_SYNC_ALWAYS)
wbc->sync_mode = WB_SYNC_ALL;
ZFS_EXIT(zsb);
sync_mode = wbc->sync_mode;
/*
* We don't want to run write_cache_pages() in SYNC mode here, because
* that would make putpage() wait for a single page to be committed to
* disk every single time, resulting in atrocious performance. Instead
* we run it once in non-SYNC mode so that the ZIL gets all the data,
* and then we commit it all in one go.
*/
wbc->sync_mode = WB_SYNC_NONE;
result = write_cache_pages(mapping, wbc, zpl_putpage, mapping);
if (sync_mode != wbc->sync_mode) {
ZFS_ENTER(zsb);
ZFS_VERIFY_ZP(zp);
if (zsb->z_log != NULL)
zil_commit(zsb->z_log, zp->z_id);
ZFS_EXIT(zsb);
/*
* We need to call write_cache_pages() again (we can't just
* return after the commit) because the previous call in
* non-SYNC mode does not guarantee that we got all the dirty
* pages (see the implementation of write_cache_pages() for
* details). That being said, this is a no-op in most cases.
*/
wbc->sync_mode = sync_mode;
result = write_cache_pages(mapping, wbc, zpl_putpage, mapping);
}
return (result);
}
/*
* Write out dirty pages to the ARC, this function is only required to
* support mmap(2). Mapped pages may be dirtied by memory operations
* which never call .write(). These dirty pages are kept in sync with
* the ARC buffers via this hook.
*/
static int
zpl_writepage(struct page *pp, struct writeback_control *wbc)
{
if (ITOZSB(pp->mapping->host)->z_os->os_sync == ZFS_SYNC_ALWAYS)
wbc->sync_mode = WB_SYNC_ALL;
return (zpl_putpage(pp, wbc, pp->mapping));
}
/*
* The only flag combination which matches the behavior of zfs_space()
* is FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE. The FALLOC_FL_PUNCH_HOLE
* flag was introduced in the 2.6.38 kernel.
*/
#if defined(HAVE_FILE_FALLOCATE) || defined(HAVE_INODE_FALLOCATE)
long
zpl_fallocate_common(struct inode *ip, int mode, loff_t offset, loff_t len)
{
int error = -EOPNOTSUPP;
#if defined(FALLOC_FL_PUNCH_HOLE) && defined(FALLOC_FL_KEEP_SIZE)
cred_t *cr = CRED();
flock64_t bf;
loff_t olen;
if (mode != (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
return (error);
crhold(cr);
if (offset < 0 || len <= 0)
return (-EINVAL);
spl_inode_lock(ip);
olen = i_size_read(ip);
if (offset > olen) {
spl_inode_unlock(ip);
return (0);
}
if (offset + len > olen)
len = olen - offset;
bf.l_type = F_WRLCK;
bf.l_whence = 0;
bf.l_start = offset;
bf.l_len = len;
bf.l_pid = 0;
error = -zfs_space(ip, F_FREESP, &bf, FWRITE, offset, cr);
spl_inode_unlock(ip);
crfree(cr);
#endif /* defined(FALLOC_FL_PUNCH_HOLE) && defined(FALLOC_FL_KEEP_SIZE) */
ASSERT3S(error, <=, 0);
return (error);
}
#endif /* defined(HAVE_FILE_FALLOCATE) || defined(HAVE_INODE_FALLOCATE) */
#ifdef HAVE_FILE_FALLOCATE
static long
zpl_fallocate(struct file *filp, int mode, loff_t offset, loff_t len)
{
return zpl_fallocate_common(filp->f_path.dentry->d_inode,
mode, offset, len);
}
#endif /* HAVE_FILE_FALLOCATE */
/*
* Map zfs file z_pflags (xvattr_t) to linux file attributes. Only file
* attributes common to both Linux and Solaris are mapped.
*/
static int
zpl_ioctl_getflags(struct file *filp, void __user *arg)
{
struct inode *ip = file_inode(filp);
unsigned int ioctl_flags = 0;
uint64_t zfs_flags = ITOZ(ip)->z_pflags;
int error;
if (zfs_flags & ZFS_IMMUTABLE)
ioctl_flags |= FS_IMMUTABLE_FL;
if (zfs_flags & ZFS_APPENDONLY)
ioctl_flags |= FS_APPEND_FL;
if (zfs_flags & ZFS_NODUMP)
ioctl_flags |= FS_NODUMP_FL;
ioctl_flags &= FS_FL_USER_VISIBLE;
error = copy_to_user(arg, &ioctl_flags, sizeof (ioctl_flags));
return (error);
}
/*
* fchange() is a helper macro to detect if we have been asked to change a
* flag. This is ugly, but the requirement that we do this is a consequence of
* how the Linux file attribute interface was designed. Another consequence is
* that concurrent modification of files suffers from a TOCTOU race. Neither
* are things we can fix without modifying the kernel-userland interface, which
* is outside of our jurisdiction.
*/
#define fchange(f0, f1, b0, b1) ((((f0) & (b0)) == (b0)) != \
(((b1) & (f1)) == (f1)))
static int
zpl_ioctl_setflags(struct file *filp, void __user *arg)
{
struct inode *ip = file_inode(filp);
uint64_t zfs_flags = ITOZ(ip)->z_pflags;
unsigned int ioctl_flags;
cred_t *cr = CRED();
xvattr_t xva;
xoptattr_t *xoap;
int error;
if (copy_from_user(&ioctl_flags, arg, sizeof (ioctl_flags)))
return (-EFAULT);
if ((ioctl_flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | FS_NODUMP_FL)))
return (-EOPNOTSUPP);
if ((ioctl_flags & ~(FS_FL_USER_MODIFIABLE)))
return (-EACCES);
if ((fchange(ioctl_flags, zfs_flags, FS_IMMUTABLE_FL, ZFS_IMMUTABLE) ||
fchange(ioctl_flags, zfs_flags, FS_APPEND_FL, ZFS_APPENDONLY)) &&
!capable(CAP_LINUX_IMMUTABLE))
return (-EACCES);
if (!zpl_inode_owner_or_capable(ip))
return (-EACCES);
xva_init(&xva);
xoap = xva_getxoptattr(&xva);
XVA_SET_REQ(&xva, XAT_IMMUTABLE);
if (ioctl_flags & FS_IMMUTABLE_FL)
xoap->xoa_immutable = B_TRUE;
XVA_SET_REQ(&xva, XAT_APPENDONLY);
if (ioctl_flags & FS_APPEND_FL)
xoap->xoa_appendonly = B_TRUE;
XVA_SET_REQ(&xva, XAT_NODUMP);
if (ioctl_flags & FS_NODUMP_FL)
xoap->xoa_nodump = B_TRUE;
crhold(cr);
error = -zfs_setattr(ip, (vattr_t *)&xva, 0, cr);
crfree(cr);
return (error);
}
static long
zpl_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case FS_IOC_GETFLAGS:
return (zpl_ioctl_getflags(filp, (void *)arg));
case FS_IOC_SETFLAGS:
return (zpl_ioctl_setflags(filp, (void *)arg));
default:
return (-ENOTTY);
}
}
#ifdef CONFIG_COMPAT
static long
zpl_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
return (zpl_ioctl(filp, cmd, arg));
}
#endif /* CONFIG_COMPAT */
const struct address_space_operations zpl_address_space_operations = {
.readpages = zpl_readpages,
.readpage = zpl_readpage,
.writepage = zpl_writepage,
.writepages = zpl_writepages,
};
const struct file_operations zpl_file_operations = {
.open = zpl_open,
.release = zpl_release,
.llseek = zpl_llseek,
.read = zpl_read,
.write = zpl_write,
.aio_read = zpl_aio_read,
.aio_write = zpl_aio_write,
.mmap = zpl_mmap,
.fsync = zpl_fsync,
.aio_fsync = zpl_aio_fsync,
#ifdef HAVE_FILE_FALLOCATE
.fallocate = zpl_fallocate,
#endif /* HAVE_FILE_FALLOCATE */
.unlocked_ioctl = zpl_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = zpl_compat_ioctl,
#endif
};
const struct file_operations zpl_dir_file_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
#ifdef HAVE_VFS_ITERATE
.iterate = zpl_iterate,
#else
.readdir = zpl_readdir,
#endif
.fsync = zpl_fsync,
.unlocked_ioctl = zpl_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = zpl_compat_ioctl,
#endif
};