diff options
| author | David Woodhouse <dwmw2@infradead.org> | 2009-04-20 23:18:37 +0100 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2009-04-20 23:01:16 -0400 |
| commit | 2f9092e1020246168b1309b35e085ecd7ff9ff72 (patch) | |
| tree | f8318c1e62e789718ae7637869f6c075b815bcb2 /fs/namei.c | |
| parent | 1ba0c7dbbbc24230394100c5f0d0df38cb400cff (diff) | |
Fix i_mutex vs. readdir handling in nfsd
Commit 14f7dd63 ("Copy XFS readdir hack into nfsd code") introduced a
bug to generic code which had been extant for a long time in the XFS
version -- it started to call through into lookup_one_len() and hence
into the file systems' ->lookup() methods without i_mutex held on the
directory.
This patch fixes it by locking the directory's i_mutex again before
calling the filldir functions. The original deadlocks which commit
14f7dd63 was designed to avoid are still avoided, because they were due
to fs-internal locking, not i_mutex.
While we're at it, fix the return type of nfsd_buffered_readdir() which
should be a __be32 not an int -- it's an NFS errno, not a Linux errno.
And return nfserrno(-ENOMEM) when allocation fails, not just -ENOMEM.
Sparse would have caught that, if it wasn't so busy bitching about
__cold__.
Commit 05f4f678 ("nfsd4: don't do lookup within readdir in recovery
code") introduced a similar problem with calling lookup_one_len()
without i_mutex, which this patch also addresses. To fix that, it was
necessary to fix the called functions so that they expect i_mutex to be
held; that part was done by J. Bruce Fields.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Umm-I-can-live-with-that-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: J. R. Okajima <hooanon05@yahoo.co.jp>
Tested-by: J. Bruce Fields <bfields@citi.umich.edu>
LKML-Reference: <8036.1237474444@jrobl>
Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/namei.c b/fs/namei.c index b8433ebfae0..78f253cd2d4 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1248,6 +1248,8 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) int err; struct qstr this; + WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); + err = __lookup_one_len(name, &this, base, len); if (err) return ERR_PTR(err); |