From: Ernesto A. Fernández <ernesto.mnd.fernandez@xxxxxxxxx> Subject: hfsplus: avoid deadlock on file truncation After an extent is removed from the extent tree, the corresponding bits are also cleared from the block allocation file. This is currently done without releasing the tree lock. The problem is that the allocation file has extents of its own; if it is fragmented enough, some of them may be in the extent tree as well, and hfsplus_get_block() will try to take the lock again. To avoid deadlock, only hold the extent tree lock during the actual tree operations. Link: http://lkml.kernel.org/r/20180709202549.auxwkb6memlegb4a@eaf Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@xxxxxxxxx> Reported-by: Anatoly Trosinenko <anatoly.trosinenko@xxxxxxxxx> Cc: Viacheslav Dubeyko <slava@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/hfsplus/extents.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) --- a/fs/hfsplus/extents.c~hfsplus-avoid-deadlock-on-file-truncation +++ a/fs/hfsplus/extents.c @@ -336,6 +336,9 @@ static int hfsplus_free_extents(struct s int i; int err = 0; + /* Mapping the allocation file may lock the extent tree */ + WARN_ON(mutex_is_locked(&HFSPLUS_SB(sb)->ext_tree->tree_lock)); + hfsplus_dump_extent(extent); for (i = 0; i < 8; extent++, i++) { count = be32_to_cpu(extent->block_count); @@ -415,11 +418,13 @@ int hfsplus_free_fork(struct super_block if (res) break; start = be32_to_cpu(fd.key->ext.start_block); - hfsplus_free_extents(sb, ext_entry, - total_blocks - start, - total_blocks); hfs_brec_remove(&fd); + + mutex_unlock(&fd.tree->tree_lock); + hfsplus_free_extents(sb, ext_entry, total_blocks - start, + total_blocks); total_blocks = start; + mutex_lock(&fd.tree->tree_lock); } while (total_blocks > blocks); hfs_find_exit(&fd); @@ -576,15 +581,20 @@ void hfsplus_file_truncate(struct inode } while (1) { if (alloc_cnt == hip->first_blocks) { + mutex_unlock(&fd.tree->tree_lock); hfsplus_free_extents(sb, hip->first_extents, alloc_cnt, alloc_cnt - blk_cnt); hfsplus_dump_extent(hip->first_extents); hip->first_blocks = blk_cnt; + mutex_lock(&fd.tree->tree_lock); break; } res = __hfsplus_ext_cache_extent(&fd, inode, alloc_cnt); if (res) break; + hfs_brec_remove(&fd); + + mutex_unlock(&fd.tree->tree_lock); start = hip->cached_start; hfsplus_free_extents(sb, hip->cached_extents, alloc_cnt - start, alloc_cnt - blk_cnt); @@ -596,7 +606,7 @@ void hfsplus_file_truncate(struct inode alloc_cnt = start; hip->cached_start = hip->cached_blocks = 0; hip->extent_state &= ~(HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW); - hfs_brec_remove(&fd); + mutex_lock(&fd.tree->tree_lock); } hfs_find_exit(&fd); _
