FAILED: patch "[PATCH] ext2/dax: Fix ext2_setsize when len is page aligned" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x fcced95b6ba2a507a83b8b3e0358a8ac16b13e35
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023072139-gently-poster-a61c@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

fcced95b6ba2 ("ext2/dax: Fix ext2_setsize when len is page aligned")
0cc5b4ce7a37 ("ext2: remove nobh support")
67235182a41c ("mm/migrate: Convert buffer_migrate_page() to buffer_migrate_folio()")
eca66389744d ("ocfs2: Convert to release_folio")
f132ab7d3ab0 ("fs: Convert mpage_readpage to mpage_read_folio")
9d6b0cd75798 ("fs: Remove flags parameter from aops->write_begin")
8371f30cf774 ("fs: Remove aop flags parameter from nobh_write_begin()")
e621900ad28b ("fs: Convert __set_page_dirty_buffers to block_dirty_folio")
7ba13abbd31e ("fs: Turn block_invalidatepage into block_invalidate_folio")
128d1f8241d6 ("fs: Add invalidate_folio() aops method")
5ad6b2bdaaea ("fs: Turn do_invalidatepage() into folio_invalidate()")
3acbdbf42e94 ("Merge tag 'libnvdimm-for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From fcced95b6ba2a507a83b8b3e0358a8ac16b13e35 Mon Sep 17 00:00:00 2001
From: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Date: Fri, 21 Apr 2023 15:16:11 +0530
Subject: [PATCH] ext2/dax: Fix ext2_setsize when len is page aligned

PAGE_ALIGN(x) macro gives the next highest value which is multiple of
pagesize. But if x is already page aligned then it simply returns x.
So, if x passed is 0 in dax_zero_range() function, that means the
length gets passed as 0 to ->iomap_begin().

In ext2 it then calls ext2_get_blocks -> max_blocks as 0 and hits bug_on
here in ext2_get_blocks().
	BUG_ON(maxblocks == 0);

Instead we should be calling dax_truncate_page() here which takes
care of it. i.e. it only calls dax_zero_range if the offset is not
page/block aligned.

This can be easily triggered with following on fsdax mounted pmem
device.

dd if=/dev/zero of=file count=1 bs=512
truncate -s 0 file

[79.525838] EXT2-fs (pmem0): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
[79.529376] ext2 filesystem being mounted at /mnt1/test supports timestamps until 2038 (0x7fffffff)
[93.793207] ------------[ cut here ]------------
[93.795102] kernel BUG at fs/ext2/inode.c:637!
[93.796904] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[93.798659] CPU: 0 PID: 1192 Comm: truncate Not tainted 6.3.0-rc2-xfstests-00056-g131086faa369 #139
[93.806459] RIP: 0010:ext2_get_blocks.constprop.0+0x524/0x610
<...>
[93.835298] Call Trace:
[93.836253]  <TASK>
[93.837103]  ? lock_acquire+0xf8/0x110
[93.838479]  ? d_lookup+0x69/0xd0
[93.839779]  ext2_iomap_begin+0xa7/0x1c0
[93.841154]  iomap_iter+0xc7/0x150
[93.842425]  dax_zero_range+0x6e/0xa0
[93.843813]  ext2_setsize+0x176/0x1b0
[93.845164]  ext2_setattr+0x151/0x200
[93.846467]  notify_change+0x341/0x4e0
[93.847805]  ? lock_acquire+0xf8/0x110
[93.849143]  ? do_truncate+0x74/0xe0
[93.850452]  ? do_truncate+0x84/0xe0
[93.851739]  do_truncate+0x84/0xe0
[93.852974]  do_sys_ftruncate+0x2b4/0x2f0
[93.854404]  do_syscall_64+0x3f/0x90
[93.855789]  entry_SYSCALL_64_after_hwframe+0x72/0xdc

CC: stable@vger.kernel.org
Fixes: 2aa3048e03d3 ("iomap: switch iomap_zero_range to use iomap_iter")
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <046a58317f29d9603d1068b2bbae47c2332c17ae.1682069716.git.ritesh.list@gmail.com>

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 26f135e7ffce..dc76147e7b07 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1259,9 +1259,8 @@ static int ext2_setsize(struct inode *inode, loff_t newsize)
 	inode_dio_wait(inode);
 
 	if (IS_DAX(inode))
-		error = dax_zero_range(inode, newsize,
-				       PAGE_ALIGN(newsize) - newsize, NULL,
-				       &ext2_iomap_ops);
+		error = dax_truncate_page(inode, newsize, NULL,
+					  &ext2_iomap_ops);
 	else
 		error = block_truncate_page(inode->i_mapping,
 				newsize, ext2_get_block);