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| author | NeilBrown <neilb@suse.com> | 2017-07-05 05:22:20 +0300 |
|---|---|---|
| committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2017-07-13 23:00:08 +0300 |
| commit | cc89684c9a265828ce061037f1f79f4a68ccd3f7 (patch) | |
| tree | 8eb80f6fa20854f66e2c43a228a1bb5ea5c08288 /fs/nfs/dir.c | |
| parent | 22368ff11d72eb06051f9b51abbc6842496c2d3a (diff) | |
| download | linux-cc89684c9a265828ce061037f1f79f4a68ccd3f7.tar.xz | |
NFS: only invalidate dentrys that are clearly invalid.
Since commit bafc9b754f75 ("vfs: More precise tests in d_invalidate")
in v3.18, a return of '0' from ->d_revalidate() will cause the dentry
to be invalidated even if it has filesystems mounted on or it or on a
descendant. The mounted filesystem is unmounted.
This means we need to be careful not to return 0 unless the directory
referred to truly is invalid. So -ESTALE or -ENOENT should invalidate
the directory. Other errors such a -EPERM or -ERESTARTSYS should be
returned from ->d_revalidate() so they are propagated to the caller.
A particular problem can be demonstrated by:
1/ mount an NFS filesystem using NFSv3 on /mnt
2/ mount any other filesystem on /mnt/foo
3/ ls /mnt/foo
4/ turn off network, or otherwise make the server unable to respond
5/ ls /mnt/foo &
6/ cat /proc/$!/stack # note that nfs_lookup_revalidate is in the call stack
7/ kill -9 $! # this results in -ERESTARTSYS being returned
8/ observe that /mnt/foo has been unmounted.
This patch changes nfs_lookup_revalidate() to only treat
-ESTALE from nfs_lookup_verify_inode() and
-ESTALE or -ENOENT from ->lookup()
as indicating an invalid inode. Other errors are returned.
Also nfs_check_inode_attributes() is changed to return -ESTALE rather
than -EIO. This is consistent with the error returned in similar
circumstances from nfs_update_inode().
As this bug allows any user to unmount a filesystem mounted on an NFS
filesystem, this fix is suitable for stable kernels.
Fixes: bafc9b754f75 ("vfs: More precise tests in d_invalidate")
Cc: stable@vger.kernel.org (v3.18+)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'fs/nfs/dir.c')
| -rw-r--r-- | fs/nfs/dir.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index ab69ebb48350..98b18aaf45c9 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1115,11 +1115,13 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags) /* Force a full look up iff the parent directory has changed */ if (!nfs_is_exclusive_create(dir, flags) && nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) { - - if (nfs_lookup_verify_inode(inode, flags)) { + error = nfs_lookup_verify_inode(inode, flags); + if (error) { if (flags & LOOKUP_RCU) return -ECHILD; - goto out_zap_parent; + if (error == -ESTALE) + goto out_zap_parent; + goto out_error; } nfs_advise_use_readdirplus(dir); goto out_valid; @@ -1144,8 +1146,10 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags) trace_nfs_lookup_revalidate_enter(dir, dentry, flags); error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label); trace_nfs_lookup_revalidate_exit(dir, dentry, flags, error); - if (error) + if (error == -ESTALE || error == -ENOENT) goto out_bad; + if (error) + goto out_error; if (nfs_compare_fh(NFS_FH(inode), fhandle)) goto out_bad; if ((error = nfs_refresh_inode(inode, fattr)) != 0) |