From 720f9616ce420c93318a6e19928900cd6e156bea Mon Sep 17 00:00:00 2001 From: Zhang Yi Date: Wed, 8 Sep 2021 20:08:50 +0800 Subject: [PATCH] ext4: prevent partial update of the extent blocks BugLink: https://bugs.launchpad.net/bugs/1956305 commit 0f2f87d51aebcf71a709b52f661d681594c7dffa upstream. In the most error path of current extents updating operations are not roll back partial updates properly when some bad things happens(.e.g in ext4_ext_insert_extent()). So we may get an inconsistent extents tree if journal has been aborted due to IO error, which may probability lead to BUGON later when we accessing these extent entries in errors=continue mode. This patch drop extent buffer's verify flag before updatng the contents in ext4_ext_get_access(), and reset it after updating in __ext4_ext_dirty(). After this patch we could force to check the extent buffer if extents tree updating was break off, make sure the extents are consistent. Signed-off-by: Zhang Yi Reviewed-by: Theodore Ts'o Link: https://lore.kernel.org/r/20210908120850.4012324-4-yi.zhang@huawei.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman Signed-off-by: Andrea Righi --- fs/ext4/extents.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 01c00ae8e06d..e7703b10830a 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -136,15 +136,25 @@ int ext4_datasem_ensure_credits(handle_t *handle, struct inode *inode, static int ext4_ext_get_access(handle_t *handle, struct inode *inode, struct ext4_ext_path *path) { + int err = 0; + if (path->p_bh) { /* path points to block */ BUFFER_TRACE(path->p_bh, "get_write_access"); - return ext4_journal_get_write_access(handle, inode->i_sb, - path->p_bh, EXT4_JTR_NONE); + err = ext4_journal_get_write_access(handle, inode->i_sb, + path->p_bh, EXT4_JTR_NONE); + /* + * The extent buffer's verified bit will be set again in + * __ext4_ext_dirty(). We could leave an inconsistent + * buffer if the extents updating procudure break off du + * to some error happens, force to check it again. + */ + if (!err) + clear_buffer_verified(path->p_bh); } /* path points to leaf/index in inode body */ /* we use in-core data, no need to protect them */ - return 0; + return err; } /* @@ -165,6 +175,9 @@ static int __ext4_ext_dirty(const char *where, unsigned int line, /* path points to block */ err = __ext4_handle_dirty_metadata(where, line, handle, inode, path->p_bh); + /* Extents updating done, re-set verified flag */ + if (!err) + set_buffer_verified(path->p_bh); } else { /* path points to leaf/index in inode body */ err = ext4_mark_inode_dirty(handle, inode); -- 2.39.5