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authorRitesh Harjani <riteshh@linux.ibm.com>2019-12-12 11:25:55 +0530
committerTheodore Ts'o <tytso@mit.edu>2019-12-22 23:57:27 -0500
commitf629afe3369e9885fd6e9cc7a4f514b6a65cf9e9 (patch)
tree7f7b3f170985b97099e2c7b9f149ebc0975e41eb /fs/ext4/file.c
parent46cf053efec6a3a5f343fead837777efe8252a46 (diff)
downloadlinux-f629afe3369e9885fd6e9cc7a4f514b6a65cf9e9.tar.bz2
ext4: fix ext4_dax_read/write inode locking sequence for IOCB_NOWAIT
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>
Diffstat (limited to 'fs/ext4/file.c')
-rw-r--r--fs/ext4/file.c10
1 files 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);
}