For filesystems with the AS_WRITEBACK_MAY_BLOCK flag set, writeback operations may block or take an indeterminate time to complete. For example, writing data back to disk in FUSE filesystems depends on the userspace server successfully completing writeback. In this commit, wait_sb_inodes() skips waiting on writeback if the inode's mapping has AS_WRITEBACK_MAY_BLOCK set, else sync(2) may take an indeterminate amount of time to complete. If the caller wishes to ensure the data for a mapping with the AS_WRITEBACK_MAY_BLOCK flag set has actually been written back to disk, they should use fsync(2)/fdatasync(2) instead. Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx> --- fs/fs-writeback.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index d8bec3c1bb1f..c80c45972162 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -2659,6 +2659,9 @@ static void wait_sb_inodes(struct super_block *sb) if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) continue; + if (mapping_writeback_may_block(mapping)) + continue; + spin_unlock_irq(&sb->s_inode_wblist_lock); spin_lock(&inode->i_lock); -- 2.43.5
