From 4a4f9b5c7c13601c4f1b3d8c607d7439e39f40d2 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Fri, 28 Feb 2025 15:58:30 -0500 Subject: [PATCH] bcachefs: Don't set BCH_FEATURE_incompat_version_field unless requested We shouldn't be setting incompatible bits or the incompatible version field unless explicitly request or allowed - otherwise we break mounting with old kernels or userspace. Reported-by: Dave Hansen Signed-off-by: Kent Overstreet --- fs/bcachefs/super-io.c | 24 ++++++++++++++++-------- fs/bcachefs/super-io.h | 11 ++++------- 2 files changed, 20 insertions(+), 15 deletions(-) diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c index 8037ccbacf6a..a81a7b6c0989 100644 --- a/fs/bcachefs/super-io.c +++ b/fs/bcachefs/super-io.c @@ -69,14 +69,20 @@ enum bcachefs_metadata_version bch2_latest_compatible_version(enum bcachefs_meta return v; } -void bch2_set_version_incompat(struct bch_fs *c, enum bcachefs_metadata_version version) +bool bch2_set_version_incompat(struct bch_fs *c, enum bcachefs_metadata_version version) { - mutex_lock(&c->sb_lock); - SET_BCH_SB_VERSION_INCOMPAT(c->disk_sb.sb, - max(BCH_SB_VERSION_INCOMPAT(c->disk_sb.sb), version)); - c->disk_sb.sb->features[0] |= cpu_to_le64(BCH_FEATURE_incompat_version_field); - bch2_write_super(c); - mutex_unlock(&c->sb_lock); + bool ret = (c->sb.features & BIT_ULL(BCH_FEATURE_incompat_version_field)) && + version <= c->sb.version_incompat_allowed; + + if (ret) { + mutex_lock(&c->sb_lock); + SET_BCH_SB_VERSION_INCOMPAT(c->disk_sb.sb, + max(BCH_SB_VERSION_INCOMPAT(c->disk_sb.sb), version)); + bch2_write_super(c); + mutex_unlock(&c->sb_lock); + } + + return ret; } const char * const bch2_sb_fields[] = { @@ -1219,9 +1225,11 @@ void bch2_sb_upgrade(struct bch_fs *c, unsigned new_version, bool incompat) c->disk_sb.sb->version = cpu_to_le16(new_version); c->disk_sb.sb->features[0] |= cpu_to_le64(BCH_SB_FEATURES_ALL); - if (incompat) + if (incompat) { SET_BCH_SB_VERSION_INCOMPAT_ALLOWED(c->disk_sb.sb, max(BCH_SB_VERSION_INCOMPAT_ALLOWED(c->disk_sb.sb), new_version)); + c->disk_sb.sb->features[0] |= cpu_to_le64(BCH_FEATURE_incompat_version_field); + } } static int bch2_sb_ext_validate(struct bch_sb *sb, struct bch_sb_field *f, diff --git a/fs/bcachefs/super-io.h b/fs/bcachefs/super-io.h index f1ab4f943720..b4cff9ebdebb 100644 --- a/fs/bcachefs/super-io.h +++ b/fs/bcachefs/super-io.h @@ -21,17 +21,14 @@ static inline bool bch2_version_compatible(u16 version) void bch2_version_to_text(struct printbuf *, enum bcachefs_metadata_version); enum bcachefs_metadata_version bch2_latest_compatible_version(enum bcachefs_metadata_version); -void bch2_set_version_incompat(struct bch_fs *, enum bcachefs_metadata_version); +bool bch2_set_version_incompat(struct bch_fs *, enum bcachefs_metadata_version); static inline bool bch2_request_incompat_feature(struct bch_fs *c, enum bcachefs_metadata_version version) { - if (unlikely(version > c->sb.version_incompat)) { - if (version > c->sb.version_incompat_allowed) - return false; - bch2_set_version_incompat(c, version); - } - return true; + return likely(version <= c->sb.version_incompat) + ? true + : bch2_set_version_incompat(c, version); } static inline size_t bch2_sb_field_bytes(struct bch_sb_field *f) -- 2.50.1