From 8e0fa5d7b3df6e7e23e13a7250b00afe32d4e618 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Tue, 9 Jun 2020 19:21:48 +0200 Subject: Revert "btrfs: remove BTRFS_INODE_READDIO_NEED_LOCK" This reverts commit 5f008163a559d566a0ee1190a0a24f3eec6f1ea7. The patch is a simplification after direct IO port to iomap infrastructure, which gets reverted. Signed-off-by: David Sterba --- fs/btrfs/btrfs_inode.h | 18 ++++++++++++++++++ fs/btrfs/inode.c | 3 +++ 2 files changed, 21 insertions(+) diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index aeff56a0e105..e7d709505cb1 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -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, }; @@ -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 diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 44d948fbad21..2b40fcfababc 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -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) { -- cgit v1.2.3