FAILED: patch "[PATCH] ext4: fix lockdep warning when enabling MMP" failed to apply to 5.4-stable tree
Subsystems (2)
[email protected]
maintainerThe patch below does not apply to the 5.4-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-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x 949f95ff39bf188e594e7ecd8e29b82eb108f5bf
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023051544-refold-dosage-6c5f@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..
Possible dependencies:
949f95ff39bf ("ext4: fix lockdep warning when enabling MMP") 6810fad956df ("ext4: fix ext4_error_err save negative errno into superblock")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 949f95ff39bf188e594e7ecd8e29b82eb108f5bf Mon Sep 17 00:00:00 2001
From: Jan Kara <[email protected]>
Date: Tue, 11 Apr 2023 14:10:19 +0200
Subject: [PATCH] ext4: fix lockdep warning when enabling MMP
When we enable MMP in ext4_multi_mount_protect() during mount or remount, we end up calling sb_start_write() from write_mmp_block(). This triggers lockdep warning because freeze protection ranks above s_umount semaphore we are holding during mount / remount. The problem is harmless because we are guaranteed the filesystem is not frozen during mount / remount but still let's fix the warning by not grabbing freeze protection from ext4_multi_mount_protect().
fs/ext4/mmp.c +21 -9
@@ -39,28 +39,36 @@ static void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp)* Write the MMP block using REQ_SYNC to try to get the block on-disk * faster. */ -static int write_mmp_block (struct super_block *sb,struct buffer_head *bh) +static int write_mmp_block_thawed (struct super_block *sb, +struct buffer_head *bh) {struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data); -/* -* We protect against freezing so that we don't create dirty buffers -* on frozen filesystem. -*/ -sb_start_write (sb);ext4_mmp_csum_set (sb, mmp);lock_buffer (bh); bh->b_end_io = end_buffer_write_sync;get_bh (bh);submit_bh (REQ_OP_WRITE |REQ_SYNC |REQ_META |REQ_PRIO , bh);wait_on_buffer (bh); -sb_end_write (sb);if (unlikely (!buffer_uptodate (bh)))return -EIO ; -return 0 ; } +static int write_mmp_block (struct super_block *sb,struct buffer_head *bh) +{ +int err; + +/* +* We protect against freezing so that we don't create dirty buffers +* on frozen filesystem. +*/ +sb_start_write (sb); + err =write_mmp_block_thawed (sb, bh); +sb_end_write (sb); +return err; +} +/* * Read the MMP block. It _must_ be read from disk and hence we clear the * uptodate flag on the buffer.
@@ -344,7 +352,11 @@ int ext4_multi_mount_protect(struct super_block *sb, seq =mmp_new_seq (); mmp->mmp_seq =cpu_to_le32 (seq); - retval =write_mmp_block (sb, bh); +/* +* On mount / remount we are protected against fs freezing (by s_umount +* semaphore) and grabbing freeze protection upsets lockdep +*/ + retval =write_mmp_block_thawed (sb, bh);if (retval) goto failed;