[PATCH 3.12 061/182] nfsd: notify_change needs elevated write count

Jiri Slaby
2014-05-13T10:02:51Z

From: "J. Bruce Fields" <bfields@redhat.com>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 9f67f189939eccaa54f3d2c9cf10788abaf2d584 upstream.

Looks like this bug has been here since these write counts were
introduced, not sure why it was just noticed now.

Thanks also to Jan Kara for pointing out the problem.

Reported-by: Matthew Rahtz <mrahtz@rapitasystems.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
fs/nfsd/vfs.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 72cb28e73ca0..e9a80e4553a3 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -407,6 +407,7 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
umode_t ftype = 0;
__be32 err;
int host_err;
+ bool get_write_count;
int size_change = 0;

if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME | ATTR_SIZE))
@@ -414,10 +415,18 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
if (iap->ia_valid & ATTR_SIZE)
ftype = S_IFREG;

+ /* Callers that do fh_verify should do the fh_want_write: */
+ get_write_count = !fhp->fh_dentry;
+
/* Get inode */
err = fh_verify(rqstp, fhp, ftype, accmode);
if (err)
goto out;
+ if (get_write_count) {
+ host_err = fh_want_write(fhp);
+ if (host_err)
+ return nfserrno(host_err);
+ }

dentry = fhp->fh_dentry;
inode = dentry->d_inode;
--
1.9.3