btrfs: remove BTRFS_INODE_READDIO_NEED_LOCK

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.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <jth@kernel.org>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index e7d7095..aeff56a 100644 (file)
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -28,7 +28,6 @@ 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,
 };
@@ -313,23 +312,6 @@ struct btrfs_dio_private {
        u8 csums[];
 };
 
-/*
- * 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 501842f..0c47f79 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4750,10 +4750,7 @@ 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) {