From 87e79fa122bc9a6576f1690ee264fcbd77d3ab58 Mon Sep 17 00:00:00 2001 From: Li Chen Date: Thu, 11 Dec 2025 19:51:38 +0800 Subject: ext4: mark inode format migration fast-commit ineligible Fast commits only log operations that have dedicated replay support. Inode format migration (indirect<->extent layout changes via EXT4_IOC_MIGRATE or toggling EXT4_EXTENTS_FL) rewrites the block mapping representation without going through the fast commit tracking paths. In practice these migrations 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_ext_migrate() or ext4_ind_migrate() start their journal transactions. This forces those transactions to fall back to a full commit, ensuring that the entire inode layout change is captured by the normal journal rather than partially encoded in fast commit TLVs. This change should not affect common workloads but makes format migrations safer and easier to reason about under fast commit. Testing: 1. prepare: dd if=/dev/zero of=/root/fc.img bs=1M count=0 seek=128 mkfs.ext4 -O fast_commit -F /root/fc.img mkdir -p /mnt/fc && mount -t ext4 -o loop /root/fc.img /mnt/fc 2. Created a test file and toggled the extents flag to exercise both ext4_ind_migrate() and ext4_ext_migrate(): touch /mnt/fc/migtest chattr -e /mnt/fc/migtest chattr +e /mnt/fc/migtest 3. Verified fast-commit ineligible statistics: tail -n 1 /proc/fs/ext4/loop0/fc_info "Inode format migration": 2 Signed-off-by: Li Chen Link: https://patch.msgid.link/20251211115146.897420-2-me@linux.beauty Signed-off-by: Theodore Ts'o --- include/trace/events/ext4.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/trace') diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h index fd76d14c2776..31598a7810d6 100644 --- a/include/trace/events/ext4.h +++ b/include/trace/events/ext4.h @@ -102,6 +102,7 @@ TRACE_DEFINE_ENUM(EXT4_FC_REASON_RENAME_DIR); TRACE_DEFINE_ENUM(EXT4_FC_REASON_FALLOC_RANGE); TRACE_DEFINE_ENUM(EXT4_FC_REASON_INODE_JOURNAL_DATA); TRACE_DEFINE_ENUM(EXT4_FC_REASON_ENCRYPTED_FILENAME); +TRACE_DEFINE_ENUM(EXT4_FC_REASON_MIGRATE); TRACE_DEFINE_ENUM(EXT4_FC_REASON_MAX); #define show_fc_reason(reason) \ @@ -115,7 +116,8 @@ TRACE_DEFINE_ENUM(EXT4_FC_REASON_MAX); { EXT4_FC_REASON_RENAME_DIR, "RENAME_DIR"}, \ { EXT4_FC_REASON_FALLOC_RANGE, "FALLOC_RANGE"}, \ { EXT4_FC_REASON_INODE_JOURNAL_DATA, "INODE_JOURNAL_DATA"}, \ - { EXT4_FC_REASON_ENCRYPTED_FILENAME, "ENCRYPTED_FILENAME"}) + { EXT4_FC_REASON_ENCRYPTED_FILENAME, "ENCRYPTED_FILENAME"}, \ + { EXT4_FC_REASON_MIGRATE, "MIGRATE"}) TRACE_DEFINE_ENUM(CR_POWER2_ALIGNED); TRACE_DEFINE_ENUM(CR_GOAL_LEN_FAST); -- cgit v1.2.3