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Revert "btrfs: remove BTRFS_INODE_READDIO_NEED_LOCK"
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This reverts commit 5f00816.

The patch is a simplification after direct IO port to iomap
infrastructure, which gets reverted.

Signed-off-by: David Sterba <dsterba@suse.com>
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David Sterba committed Jun 9, 2020
1 parent f4c48b4 commit 8e0fa5d
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Showing 2 changed files with 21 additions and 0 deletions.
18 changes: 18 additions & 0 deletions fs/btrfs/btrfs_inode.h
Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ 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,
};
Expand Down Expand Up @@ -312,6 +313,23 @@ 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
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3 changes: 3 additions & 0 deletions fs/btrfs/inode.c
Original file line number Diff line number Diff line change
Expand Up @@ -4811,7 +4811,10 @@ 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) {
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