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@xxxxxxx>
Reviewed-by: Matthew Bobrowski <mbobrowski@xxxxxxxxxxxxxx>
Tested-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
---
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 6a7293a5cda2..977ac58dc718 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -88,9 +88,10 @@ 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);
}
/*
@@ -487,9 +488,10 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
bool extend = false;
struct inode *inode = file_inode(iocb->ki_filp);
- 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);
}
--
2.21.0
