FAILED: patch "[PATCH] f2fs: add READ_ONCE() for i_blocks in f2fs_update_inode()" failed to apply to 5.15-stable tree

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 <[email protected]>.

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 5471834a96fb697874be2ca0b052e74bcf3c23d1
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026051228-echo-earshot-7ef7@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 5471834a96fb697874be2ca0b052e74bcf3c23d1 Mon Sep 17 00:00:00 2001
From: Cen Zhang <[email protected]>
Date: Wed, 18 Mar 2026 15:32:53 +0800
Subject: [PATCH] f2fs: add READ_ONCE() for i_blocks in f2fs_update_inode()

f2fs_update_inode() reads inode->i_blocks without holding i_lock to serialize it to the on-disk inode, while concurrent truncate or allocation paths may modify i_blocks under i_lock. Since blkcnt_t is u64, this risks torn reads on 32-bit architectures.

Following the approach in ext4_inode_blocks_set(), add READ_ONCE() to prevent potential compiler-induced tearing.

index e0f850b3f0c3..89240be8cc59 100644
@@ -687,7 +687,7 @@ void f2fs_update_inode(struct inode *inode, struct folio *node_folio)
 	ri->i_uid = cpu_to_le32(i_uid_read(inode));
 	ri->i_gid = cpu_to_le32(i_gid_read(inode));
 	ri->i_links = cpu_to_le32(inode->i_nlink);
-	ri->i_blocks = cpu_to_le64(SECTOR_TO_BLOCK(inode->i_blocks) + 1);
+	ri->i_blocks = cpu_to_le64(SECTOR_TO_BLOCK(READ_ONCE(inode->i_blocks)) + 1);
 
 	if (!f2fs_is_atomic_file(inode) ||
 			is_inode_flag_set(inode, FI_ATOMIC_COMMITTED))