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 <dsterba@suse.com>

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index aeff56a..e7d7095 100644 (file)
--- 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 44d948f..2b40fcf 100644 (file)
--- 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) {