[PATCH 8/8] btrfs: remove BTRFS_INODE_READDIO_NEED_LOCK

Goldwyn Rodrigues
2019-12-13T20:41:13Z

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

Since we now perform direct reads using i_rwsem, we can remove this
inode flag used to co-ordinate unlocked reads.

The truncate call takes i_rwsem. This means it is correctly synchronized
with concurrent direct reads.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <jth@kernel.org>
---
fs/btrfs/btrfs_inode.h | 18 ------------------
fs/btrfs/inode.c | 3 ---
2 files changed, 21 deletions(-)

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 4e12a477d32e..cd8f378ed8e7 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -27,7 +27,6 @@ enum {
BTRFS_INODE_NEEDS_FULL_SYNC,
BTRFS_INODE_COPY_EVERYTHING,
BTRFS_INODE_IN_DELALLOC_LIST,
- BTRFS_INODE_READDIO_NEED_LOCK,
BTRFS_INODE_HAS_PROPS,
BTRFS_INODE_SNAPSHOT_FLUSH,
};
@@ -317,23 +316,6 @@ struct btrfs_dio_private {
blk_status_t);
};

-/*
- * Disable DIO read nolock optimization, so new dio readers will be forced
- * to grab i_mutex. It is used to avoid the endless truncate due to
- * nonlocked dio read.
- */
-static inline void btrfs_inode_block_unlocked_dio(struct btrfs_inode *inode)
-{
- set_bit(BTRFS_INODE_READDIO_NEED_LOCK, &inode->runtime_flags);
- smp_mb();
-}
-
-static inline void btrfs_inode_resume_unlocked_dio(struct btrfs_inode *inode)
-{
- smp_mb__before_atomic();
- clear_bit(BTRFS_INODE_READDIO_NEED_LOCK, &inode->runtime_flags);
-}
-
/* Array of bytes with variable length, hexadecimal format 0x1234 */
#define CSUM_FMT "0x%*phN"
#define CSUM_FMT_VALUE(size, bytes) size, bytes
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 07220194ffb8..68adb7958ef4 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5273,10 +5273,7 @@ static int btrfs_setsize(struct inode *inode, struct iattr *attr)

truncate_setsize(inode, newsize);

- /* Disable nonlocked read DIO to avoid the endless truncate */
- btrfs_inode_block_unlocked_dio(BTRFS_I(inode));
inode_dio_wait(inode);
- btrfs_inode_resume_unlocked_dio(BTRFS_I(inode));

ret = btrfs_truncate(inode, newsize == oldsize);
if (ret && inode->i_nlink) {
--
2.16.4