From: Li Chen Date: Thu, 11 Dec 2025 11:51:42 +0000 (+0800) Subject: ext4: mark group extend fast-commit ineligible X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1f8dd813a1c771b13c303f73d876164bc9b327cc;p=thirdparty%2Flinux.git ext4: mark group extend fast-commit ineligible Fast commits only log operations that have dedicated replay support. EXT4_IOC_GROUP_EXTEND grows the filesystem to the end of the last block group and updates the same on-disk metadata without going through the fast commit tracking paths. In practice these operations are rare and usually followed by further updates, but mixing them into a fast commit makes the overall semantics harder to reason about and risks replay gaps if new call sites appear. Teach ext4 to mark the filesystem fast-commit ineligible when EXT4_IOC_GROUP_EXTEND grows the filesystem. This forces those transactions to fall back to a full commit, ensuring that the group extension changes are captured by the normal journal rather than partially encoded in fast commit TLVs. This change should not affect common workloads but makes online resize via GROUP_EXTEND safer and easier to reason about under fast commit. Testing: 1. prepare: dd if=/dev/zero of=/root/fc_resize.img bs=1M count=0 seek=256 mkfs.ext4 -O fast_commit -F /root/fc_resize.img mkdir -p /mnt/fc_resize && mount -t ext4 -o loop /root/fc_resize.img /mnt/fc_resize 2. Extended the filesystem to the end of the last block group using a helper that calls EXT4_IOC_GROUP_EXTEND on the mounted filesystem and checked fc_info: ./group_extend_helper /mnt/fc_resize cat /proc/fs/ext4/loop0/fc_info shows the "Resize" ineligible reason increased. 3. Fsynced a file on the resized filesystem and confirmed that the fast commit ineligible counter incremented for the resize transaction: touch /mnt/fc_resize/file /root/fsync_file /mnt/fc_resize/file sync cat /proc/fs/ext4/loop0/fc_info Signed-off-by: Li Chen Link: https://patch.msgid.link/20251211115146.897420-6-me@linux.beauty Signed-off-by: Theodore Ts'o --- diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index 5109b005e0286..e5e197ac7d88b 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -1612,6 +1612,8 @@ setversion_out: err = ext4_group_extend(sb, EXT4_SB(sb)->s_es, n_blocks_count); if (EXT4_SB(sb)->s_journal) { + ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_RESIZE, + NULL); jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal); err2 = jbd2_journal_flush(EXT4_SB(sb)->s_journal, 0); jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);