79065ed5a4
There seems to be a annoying problem using NFSv4 to access ZFS
file systems under certain circumstances. It's easily reproduced:
nfs_client1: mount server:/export /mnt
nfs_client1: cd /mnt
nfs_client1: echo foo >junk
nfs_client1: cat junk
foo
Now on a different NFSv4 client:
nfs_client2: mount server:/export /mnt
nfs_client2: cd /mnt
nfs_client2: vi junk
# Make some changes to /mnt/junk and save
# This change the inode associated with /mnt/junk
Now back to the original client:
nfs_client1: cat junk
cat: junk: No such file or directory
Admittedly NFSv4 is not advertised as a cluster file system that
maintains a completely coherent view of data across multiple nodes.
But it does have some mechanisms built in that try to deal with
situations like the above. Namely, it employs specialized file
handle lookup routines that return ESTALE when a file handle contains
a non-existant inode value. The ESTALE return triggers a return
full file path lookup from the client to determine if the file has
actually gone away or if the cached file handle is no longer valid.
ZFS behavior can be brought into line with other file systems
(e.g., ext4) by applying the following patch:
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3224
174 lines
4.1 KiB
C
174 lines
4.1 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2011 Gunnar Beutner
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* Copyright (c) 2012 Cyril Plisko. All rights reserved.
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*/
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#include <sys/zfs_vnops.h>
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#include <sys/zfs_znode.h>
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#include <sys/zfs_ctldir.h>
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#include <sys/zpl.h>
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static int
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#ifdef HAVE_ENCODE_FH_WITH_INODE
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zpl_encode_fh(struct inode *ip, __u32 *fh, int *max_len, struct inode *parent)
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{
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#else
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zpl_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len, int connectable)
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{
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struct inode *ip = dentry->d_inode;
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#endif /* HAVE_ENCODE_FH_WITH_INODE */
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fstrans_cookie_t cookie;
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fid_t *fid = (fid_t *)fh;
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int len_bytes, rc;
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len_bytes = *max_len * sizeof (__u32);
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if (len_bytes < offsetof(fid_t, fid_data))
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return (255);
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fid->fid_len = len_bytes - offsetof(fid_t, fid_data);
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cookie = spl_fstrans_mark();
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if (zfsctl_is_node(ip))
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rc = zfsctl_fid(ip, fid);
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else
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rc = zfs_fid(ip, fid);
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spl_fstrans_unmark(cookie);
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len_bytes = offsetof(fid_t, fid_data) + fid->fid_len;
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*max_len = roundup(len_bytes, sizeof (__u32)) / sizeof (__u32);
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return (rc == 0 ? FILEID_INO32_GEN : 255);
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}
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static struct dentry *
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zpl_dentry_obtain_alias(struct inode *ip)
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{
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struct dentry *result;
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#ifdef HAVE_D_OBTAIN_ALIAS
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result = d_obtain_alias(ip);
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#else
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result = d_alloc_anon(ip);
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if (result == NULL) {
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iput(ip);
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result = ERR_PTR(-ENOMEM);
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}
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#endif /* HAVE_D_OBTAIN_ALIAS */
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return (result);
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}
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static struct dentry *
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zpl_fh_to_dentry(struct super_block *sb, struct fid *fh,
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int fh_len, int fh_type)
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{
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fid_t *fid = (fid_t *)fh;
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fstrans_cookie_t cookie;
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struct inode *ip;
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int len_bytes, rc;
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len_bytes = fh_len * sizeof (__u32);
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if (fh_type != FILEID_INO32_GEN ||
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len_bytes < offsetof(fid_t, fid_data) ||
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len_bytes < offsetof(fid_t, fid_data) + fid->fid_len)
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return (ERR_PTR(-EINVAL));
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cookie = spl_fstrans_mark();
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rc = zfs_vget(sb, &ip, fid);
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spl_fstrans_unmark(cookie);
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if (rc) {
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/*
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* If we see ENOENT it might mean that an NFSv4 * client
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* is using a cached inode value in a file handle and
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* that the sought after file has had its inode changed
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* by a third party. So change the error to ESTALE
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* which will trigger a full lookup by the client and
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* will find the new filename/inode pair if it still
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* exists.
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*/
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if (rc == ENOENT)
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rc = ESTALE;
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return (ERR_PTR(-rc));
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}
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ASSERT((ip != NULL) && !IS_ERR(ip));
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return (zpl_dentry_obtain_alias(ip));
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}
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static struct dentry *
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zpl_get_parent(struct dentry *child)
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{
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cred_t *cr = CRED();
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fstrans_cookie_t cookie;
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struct inode *ip;
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int error;
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crhold(cr);
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cookie = spl_fstrans_mark();
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error = -zfs_lookup(child->d_inode, "..", &ip, 0, cr, NULL, NULL);
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spl_fstrans_unmark(cookie);
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crfree(cr);
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ASSERT3S(error, <=, 0);
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if (error)
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return (ERR_PTR(error));
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return (zpl_dentry_obtain_alias(ip));
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}
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#ifdef HAVE_COMMIT_METADATA
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static int
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zpl_commit_metadata(struct inode *inode)
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{
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cred_t *cr = CRED();
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fstrans_cookie_t cookie;
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int error;
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crhold(cr);
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cookie = spl_fstrans_mark();
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error = -zfs_fsync(inode, 0, cr);
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spl_fstrans_unmark(cookie);
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crfree(cr);
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ASSERT3S(error, <=, 0);
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return (error);
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}
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#endif /* HAVE_COMMIT_METADATA */
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const struct export_operations zpl_export_operations = {
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.encode_fh = zpl_encode_fh,
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.fh_to_dentry = zpl_fh_to_dentry,
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.get_parent = zpl_get_parent,
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#ifdef HAVE_COMMIT_METADATA
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.commit_metadata = zpl_commit_metadata,
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#endif /* HAVE_COMMIT_METADATA */
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};
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