diff mbox series

[PATCHv4,1/3] ext4: fix ext4_dax_read/write inode locking sequence for IOCB_NOWAIT

Message ID 20191205064624.13419-2-riteshh@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series Fix inode_lock sequence to scale performance of DIO mixed R/W workload | expand

Commit Message

Ritesh Harjani Dec. 5, 2019, 6:46 a.m. UTC 
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>
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
---
 fs/ext4/file.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
diff mbox series

Patch

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);
 	}