[PATCH 03/11] ext4: fix unwritten counter leakage
From: Dmitry Monakhov <hidden>
Date: 2012-09-28 15:44:22
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Linus Torvalds
ext4_set_io_unwritten_flag() will increment i_unwritten counter, so once we mark end_io with EXT4_END_IO_UNWRITTEN we have to revert it back on error path. - add missed error checks to prevent counter leakage - ext4_end_io_nolock() will clear EXT4_END_IO_UNWRITTEN flag to signal that conversion finished. - add BUG_ON to ext4_free_end_io() to prevent similar leakage in future. Visible effect of this bug is that unaligned aio_stress may deadlock Signed-off-by: Dmitry Monakhov <redacted> --- fs/ext4/extents.c | 21 ++++++++++++++------- fs/ext4/page-io.c | 6 +++++- 2 files changed, 19 insertions(+), 8 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index e9549f9..69e2d13 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c@@ -3545,6 +3545,8 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode, if ((flags & EXT4_GET_BLOCKS_PRE_IO)) { ret = ext4_split_unwritten_extents(handle, inode, map, path, flags); + if (ret <= 0) + goto out; /* * Flag the inode(non aio case) or end_io struct (aio case) * that this IO needs to conversion to written when IO is
@@ -3790,6 +3792,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, struct ext4_allocation_request ar; ext4_io_end_t *io = ext4_inode_aio(inode); ext4_lblk_t cluster_offset; + int set_unwritten = 0; ext_debug("blocks %u/%u requested for inode %lu\n", map->m_lblk, map->m_len, inode->i_ino);
@@ -4012,13 +4015,8 @@ got_allocated_blocks: * For non asycn direct IO case, flag the inode state * that we need to perform conversion when IO is done. */ - if ((flags & EXT4_GET_BLOCKS_PRE_IO)) { - if (io) - ext4_set_io_unwritten_flag(inode, io); - else - ext4_set_inode_state(inode, - EXT4_STATE_DIO_UNWRITTEN); - } + if ((flags & EXT4_GET_BLOCKS_PRE_IO)) + set_unwritten = 1; if (ext4_should_dioread_nolock(inode)) map->m_flags |= EXT4_MAP_UNINIT; }
@@ -4030,6 +4028,15 @@ got_allocated_blocks: if (!err) err = ext4_ext_insert_extent(handle, inode, path, &newex, flags); + + if (!err && set_unwritten) { + if (io) + ext4_set_io_unwritten_flag(inode, io); + else + ext4_set_inode_state(inode, + EXT4_STATE_DIO_UNWRITTEN); + } + if (err && free_on_err) { int fb_flags = flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE ? EXT4_FREE_BLOCKS_NO_QUOT_UPDATE : 0;
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index de77e31..9970022 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c@@ -71,6 +71,8 @@ void ext4_free_io_end(ext4_io_end_t *io) int i; BUG_ON(!io); + BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN); + if (io->page) put_page(io->page); for (i = 0; i < io->num_io_pages; i++)
@@ -94,6 +96,8 @@ int ext4_end_io_nolock(ext4_io_end_t *io) ssize_t size = io->size; int ret = 0; + BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN)); + ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p," "list->prev 0x%p\n", io, inode->i_ino, io->list.next, io->list.prev);
@@ -106,7 +110,7 @@ int ext4_end_io_nolock(ext4_io_end_t *io) "(inode %lu, offset %llu, size %zd, error %d)", inode->i_ino, offset, size, ret); }