From db489778e6f2a4034c2cd26fadda2796eba24dcd Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Mon, 9 Mar 2026 16:32:27 +0800 Subject: [PATCH] f2fs: fix to avoid migrating empty section [ Upstream commit d625a2b08c089397d3a03bff13fa8645e4ec7a01 ] It reports a bug from device w/ zufs: F2FS-fs (dm-64): Inconsistent segment (173822) type [1, 0] in SSA and SIT F2FS-fs (dm-64): Stopped filesystem due to reason: 4 Thread A Thread B - f2fs_expand_inode_data - f2fs_allocate_pinning_section - f2fs_gc_range - do_garbage_collect w/ segno #x - writepage - f2fs_allocate_data_block - new_curseg - allocate segno #x The root cause is: fallocate on pinning file may race w/ block allocation as above, result in do_garbage_collect() from fallocate() may migrate segment which is just allocated by a log, the log will update segment type in its in-memory structure, however GC will get segment type from on-disk SSA block, once segment type changes by log, we can detect such inconsistency, then shutdown filesystem. In this case, on-disk SSA shows type of segno #173822 is 1 (SUM_TYPE_NODE), however segno #173822 was just allocated as data type segment, so in-memory SIT shows type of segno #173822 is 0 (SUM_TYPE_DATA). Change as below to fix this issue: - check whether current section is empty before gc - add sanity checks on do_garbage_collect() to avoid any race case, result in migrating segment used by log. - btw, it fixes misc issue in printed logs: "SSA and SIT" -> "SIT and SSA". Fixes: 9703d69d9d15 ("f2fs: support file pinning for zoned devices") Cc: Daeho Jeong Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [ Use IS_CURSEC instead of is_cursec according to commit c1cfc87e49525 ("f2fs: introduce is_cur{seg,sec}()"). ] Signed-off-by: Robert Garcia Signed-off-by: Greg Kroah-Hartman --- fs/f2fs/gc.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index 8122135bb1ff..816a5aa263e6 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -1742,6 +1742,13 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi, GET_SUM_BLOCK(sbi, segno)); f2fs_put_page(sum_page, 0); + if (IS_CURSEC(sbi, GET_SEC_FROM_SEG(sbi, segno))) { + f2fs_err(sbi, "%s: segment %u is used by log", + __func__, segno); + f2fs_bug_on(sbi, 1); + goto skip; + } + if (get_valid_blocks(sbi, segno, false) == 0) goto freed; if (gc_type == BG_GC && __is_large_section(sbi) && @@ -1752,7 +1759,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi, sum = page_address(sum_page); if (type != GET_SUM_TYPE((&sum->footer))) { - f2fs_err(sbi, "Inconsistent segment (%u) type [%d, %d] in SSA and SIT", + f2fs_err(sbi, "Inconsistent segment (%u) type [%d, %d] in SIT and SSA", segno, type, GET_SUM_TYPE((&sum->footer))); set_sbi_flag(sbi, SBI_NEED_FSCK); f2fs_stop_checkpoint(sbi, false, @@ -2005,6 +2012,13 @@ int f2fs_gc_range(struct f2fs_sb_info *sbi, .iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS), }; + /* + * avoid migrating empty section, as it can be allocated by + * log in parallel. + */ + if (!get_valid_blocks(sbi, segno, true)) + continue; + do_garbage_collect(sbi, segno, &gc_list, FG_GC, dry_run_sections == 0); put_gc_inode(&gc_list);