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author | NeilBrown <neilb@suse.com> | 2017-07-05 12:22:20 +1000 |
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committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2017-07-13 16:00:08 -0400 |
commit | cc89684c9a265828ce061037f1f79f4a68ccd3f7 (patch) | |
tree | 8eb80f6fa20854f66e2c43a228a1bb5ea5c08288 /fs/nfs/inode.c | |
parent | 22368ff11d72eb06051f9b51abbc6842496c2d3a (diff) | |
download | op-kernel-dev-cc89684c9a265828ce061037f1f79f4a68ccd3f7.zip op-kernel-dev-cc89684c9a265828ce061037f1f79f4a68ccd3f7.tar.gz |
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/inode.c')
-rw-r--r-- | fs/nfs/inode.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 1de93ba..8c465d3 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -1315,9 +1315,9 @@ static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fat return 0; /* Has the inode gone and changed behind our back? */ if ((fattr->valid & NFS_ATTR_FATTR_FILEID) && nfsi->fileid != fattr->fileid) - return -EIO; + return -ESTALE; if ((fattr->valid & NFS_ATTR_FATTR_TYPE) && (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT)) - return -EIO; + return -ESTALE; if (!nfs_file_has_buffered_writers(nfsi)) { /* Verify a few of the more important attributes */ |