Date: Tue, 12 May 2026 19:00:51 +0000 From: Colin Percival <cperciva@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Cc: Lianwei Wang <lianwei.wang@gm.com> Subject: git: a7bc1c0c353f - releng/15.1 - fsck_msdosfs: fix FAT header correction not persisting in cache mode Message-ID: <6a0378e3.19662.b76267f@gitrepo.freebsd.org>
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The branch releng/15.1 has been updated by cperciva: URL: https://cgit.FreeBSD.org/src/commit/?id=a7bc1c0c353fc426ecfc98d42c807c74250c137d commit a7bc1c0c353fc426ecfc98d42c807c74250c137d Author: Lianwei Wang <lianwei.wang@gm.com> AuthorDate: 2026-05-09 04:56:12 +0000 Commit: Colin Percival <cperciva@FreeBSD.org> CommitDate: 2026-05-12 19:00:33 +0000 fsck_msdosfs: fix FAT header correction not persisting in cache mode When fsck_msdosfs runs with FAT32 cache mode (used for large filesystems that cannot be mmap'd), a detected FAT header correction was written into the in-memory buffer but the corresponding cache entry (fat32_cache_allentries[0]) was never marked dirty. As a result, fat_flush_fat32_cache_entry() skipped it, the corrected bytes were never written to disk, and copyfat() propagated the uncorrected on-disk data to all backup FAT copies. Every subsequent fsck run would repeat the same "FAT starts with odd byte sequence / FIXED" cycle indefinitely. Fix by marking fat32_cache_allentries[0].dirty = true after applying the in-memory correction, ensuring the chunk is flushed before copyfat() runs. Approved by: re (cperciva) Obtained from: https://android-review.googlesource.com/c/platform/external/fsck_msdos/+/4047981 (cherry picked from commit 10e342c1ec78af5a0b97739c806b16a632118fa5) (cherry picked from commit ae32d61a2e3e47bed54d861893d8e2da90fb7c76) --- sbin/fsck_msdosfs/fat.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/sbin/fsck_msdosfs/fat.c b/sbin/fsck_msdosfs/fat.c index 567bfcd428cb..5ead0b1bf783 100644 --- a/sbin/fsck_msdosfs/fat.c +++ b/sbin/fsck_msdosfs/fat.c @@ -927,6 +927,17 @@ readfat(int fs, struct bootblock *boot, struct fat_descriptor **fp) default: break; } + /* + * In cache mode the header lives in + * fat32_cache_allentries[0]. Mark it + * dirty so it is flushed to disk (either + * on eviction or in writefat()) before + * copyfat() copies the primary FAT to + * backup copies. + */ + if (fat->use_cache) + fat->fat32_cache_allentries[0].dirty = + true; } } }home | help
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