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authorJ. Bruce Fields <bfields@redhat.com>2011-09-19 15:07:41 -0400
committerJ. Bruce Fields <bfields@redhat.com>2011-09-20 14:43:39 -0400
commit3d02fa29dec920c597dd7b7db608a4bc71f088ce (patch)
tree797913e7135502f54d52fa48f1956a8ff7b640dd
parentf7a4d872078a5e143d88adb561627f637046b05a (diff)
nfsd4: fix open downgrade, again
Yet another open-management regression: - nfs4_file_downgrade() doesn't remove the BOTH access bit on downgrade, so the server's idea of the stateid's access gets out of sync with the client's. If we want to keep an O_RDWR open in this case, we should do that in the file_put_access logic rather than here. - We forgot to convert v4 access to an open mode here. This logic has proven too hard to get right. In the future we may consider: - reexamining the lock/openowner relationship (locks probably don't really need to take their own references here). - adding open upgrade/downgrade support to the vfs. - removing the atomic operations. They're redundant as long as this is all under some other lock. Also, maybe some kind of additional static checking would help catch O_/NFS4_SHARE_ACCESS confusion. Cc: stable@kernel.org Signed-off-by: J. Bruce Fields <bfields@redhat.com>
-rw-r--r--fs/nfsd/nfs4state.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index e5cba833613f..edcced18caa8 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -194,8 +194,15 @@ static void nfs4_file_put_fd(struct nfs4_file *fp, int oflag)
static void __nfs4_file_put_access(struct nfs4_file *fp, int oflag)
{
if (atomic_dec_and_test(&fp->fi_access[oflag])) {
- nfs4_file_put_fd(fp, O_RDWR);
nfs4_file_put_fd(fp, oflag);
+ /*
+ * It's also safe to get rid of the RDWR open *if*
+ * we no longer have need of the other kind of access
+ * or if we already have the other kind of open:
+ */
+ if (fp->fi_fds[1-oflag]
+ || atomic_read(&fp->fi_access[1 - oflag]) == 0)
+ nfs4_file_put_fd(fp, O_RDWR);
}
}
@@ -3500,8 +3507,9 @@ static inline void nfs4_file_downgrade(struct nfs4_ol_stateid *stp, unsigned int
int i;
for (i = 1; i < 4; i++) {
- if (test_bit(i, &stp->st_access_bmap) && !(i & to_access)) {
- nfs4_file_put_access(stp->st_file, i);
+ if (test_bit(i, &stp->st_access_bmap)
+ && ((i & to_access) != i)) {
+ nfs4_file_put_access(stp->st_file, nfs4_access_to_omode(i));
__clear_bit(i, &stp->st_access_bmap);
}
}