Hi: I recommend not backporting this patch or the other three patches apparently intended to support it to 4.19 stable. All these patches are related to ext4's bigalloc feature, which was experimental as of 4.19 (expressly noted by contemporary versions of e2fsprogs) and also suffered from a number of bugs. A significant number of additional patches that were applied to 5.X kernels over time would have to be backported to 4.19 for the patch below to function correctly. It's really not worth doing that given bigalloc's experimental status as of 4.19 and the very rare combination of the bigalloc and inline features. Thanks, Eric * Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>: > From: Eric Whitney <enwlinux@xxxxxxxxx> > > [ Upstream commit 131294c35ed6f777bd4e79d42af13b5c41bf2775 ] > > When converting files with inline data to extents, delayed allocations > made on a file system created with both the bigalloc and inline options > can result in invalid extent status cache content, incorrect reserved > cluster counts, kernel memory leaks, and potential kernel panics. > > With bigalloc, the code that determines whether a block must be > delayed allocated searches the extent tree to see if that block maps > to a previously allocated cluster. If not, the block is delayed > allocated, and otherwise, it isn't. However, if the inline option is > also used, and if the file containing the block is marked as able to > store data inline, there isn't a valid extent tree associated with > the file. The current code in ext4_clu_mapped() calls > ext4_find_extent() to search the non-existent tree for a previously > allocated cluster anyway, which typically finds nothing, as desired. > However, a side effect of the search can be to cache invalid content > from the non-existent tree (garbage) in the extent status tree, > including bogus entries in the pending reservation tree. > > To fix this, avoid searching the extent tree when allocating blocks > for bigalloc + inline files that are being converted from inline to > extent mapped. > > Signed-off-by: Eric Whitney <enwlinux@xxxxxxxxx> > Link: https://lore.kernel.org/r/20221117152207.2424-1-enwlinux@xxxxxxxxx > Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> > Cc: stable@xxxxxxxxxx > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > --- > fs/ext4/extents.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index 0bb772cd7f88..1ad4c8eb82c1 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -5984,6 +5984,14 @@ int ext4_clu_mapped(struct inode *inode, ext4_lblk_t lclu) > struct ext4_extent *extent; > ext4_lblk_t first_lblk, first_lclu, last_lclu; > > + /* > + * if data can be stored inline, the logical cluster isn't > + * mapped - no physical clusters have been allocated, and the > + * file has no extents > + */ > + if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) > + return 0; > + > /* search for the extent closest to the first block in the cluster */ > path = ext4_find_extent(inode, EXT4_C2B(sbi, lclu), NULL, 0); > if (IS_ERR(path)) { > -- > 2.35.1 > > >
