During superblock writeback waiting, skip inodes where writeback may take an indefinite amount of time or hang, as denoted by the AS_WRITEBACK_MAY_HANG mapping flag.
Currently, fuse is the only filesystem with this flag set. For a properly functioning fuse server, writeback requests are completed and there is no issue. However, if there is a bug in the fuse server and it hangs on writeback, then without this change, wait_sb_inodes() will wait forever.
Signed-off-by: Joanne Koong joannelkoong@gmail.com Fixes: 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") Reported-by: Athul Krishna athul.krishna.kr@protonmail.com --- fs/fs-writeback.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 2b35e80037fe..eb246e9fbf3d 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -2733,6 +2733,9 @@ static void wait_sb_inodes(struct super_block *sb) if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) continue;
+ if (mapping_writeback_may_hang(mapping)) + continue; + spin_unlock_irq(&sb->s_inode_wblist_lock);
spin_lock(&inode->i_lock);