From 11b036cc6c870a30734b3a1ff51f236a022331bd Mon Sep 17 00:00:00 2001 From: Christopher Haster Date: Tue, 19 Mar 2024 00:31:49 -0500 Subject: [PATCH] Prevented unnecessary superblock rewrites if old version in superblock chain Because multiple, out-of-date superblocks can exist in our superblock chain, we need to be careful to make sure newer superblock entries override older superblock entries. If we see an older on-disk minor version in the superblock chain, we were correctly overriding the on-disk minor version, but we were also leaving the "needs superblock" bit set in our consistency state. This isn't a hard-error, but would lead to a superblock rewrite every mount. The rewrite would make no progress, as the out-of-date version is effectively immutable at this point, and just waste prog cycles. This should fix that by clearing the "needs superblock" bit if we see a newer on-disk minor version. --- lfs.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/lfs.c b/lfs.c index 4e4dd9b4..0e62b5fb 100644 --- a/lfs.c +++ b/lfs.c @@ -4469,6 +4469,7 @@ static int lfs_mount_(lfs_t *lfs, const struct lfs_config *cfg) { // found older minor version? set an in-device only bit in the // gstate so we know we need to rewrite the superblock before // the first write + bool needssuperblock = false; if (minor_version < lfs_fs_disk_version_minor(lfs)) { LFS_DEBUG("Found older minor version " "v%"PRIu16".%"PRIu16" < v%"PRIu16".%"PRIu16, @@ -4476,10 +4477,11 @@ static int lfs_mount_(lfs_t *lfs, const struct lfs_config *cfg) { minor_version, lfs_fs_disk_version_major(lfs), lfs_fs_disk_version_minor(lfs)); - // note this bit is reserved on disk, so fetching more gstate - // will not interfere here - lfs_fs_prepsuperblock(lfs, true); + needssuperblock = true; } + // note this bit is reserved on disk, so fetching more gstate + // will not interfere here + lfs_fs_prepsuperblock(lfs, needssuperblock); // check superblock configuration if (superblock.name_max) {