From: Ritesh Harjani riteshh@linux.ibm.com
[ Upstream commit f629afe3369e9885fd6e9cc7a4f514b6a65cf9e9 ]
Apparently our current rwsem code doesn't like doing the trylock, then lock for real scheme. So change our dax read/write methods to just do the trylock for the RWF_NOWAIT case. This seems to fix AIM7 regression in some scalable filesystems upto ~25% in some cases. Claimed in commit 942491c9e6d6 ("xfs: fix AIM7 regression")
Reviewed-by: Jan Kara jack@suse.cz Reviewed-by: Matthew Bobrowski mbobrowski@mbobrowski.org Tested-by: Joseph Qi joseph.qi@linux.alibaba.com Signed-off-by: Ritesh Harjani riteshh@linux.ibm.com Link: https://lore.kernel.org/r/20191212055557.11151-2-riteshh@linux.ibm.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ext4/file.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 4ede0af9d6fe3..acec134da57df 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -38,9 +38,10 @@ static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) struct inode *inode = file_inode(iocb->ki_filp); ssize_t ret;
- if (!inode_trylock_shared(inode)) { - if (iocb->ki_flags & IOCB_NOWAIT) + if (iocb->ki_flags & IOCB_NOWAIT) { + if (!inode_trylock_shared(inode)) return -EAGAIN; + } else { inode_lock_shared(inode); } /* @@ -188,9 +189,10 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) struct inode *inode = file_inode(iocb->ki_filp); ssize_t ret;
- if (!inode_trylock(inode)) { - if (iocb->ki_flags & IOCB_NOWAIT) + if (iocb->ki_flags & IOCB_NOWAIT) { + if (!inode_trylock(inode)) return -EAGAIN; + } else { inode_lock(inode); } ret = ext4_write_checks(iocb, from);