From 3d02fa29dec920c597dd7b7db608a4bc71f088ce Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Mon, 19 Sep 2011 15:07:41 -0400 Subject: [PATCH] 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 --- fs/nfsd/nfs4state.c | 14 +++++++++++--- 1 file 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); } } -- 2.39.5