[PATCH v2 0/4] btrfs: rescue= mount options enhancement to support interrupted csum conversion

[PATCH v2 0/4] btrfs: rescue= mount options enhancement to support interrupted csum conversion

[Qu Wenruo]

[CHANGELOG]
v2:
- Add the new rescue options to supported rescue options sysfs interface
- Add the state char 'S' for skipping metadata csum
- Add an info line of unsupported super flags if rescue=ignoresuperflags
  is specified
- Add const prefix for one-time btrfs_test_opt() result

[REPO]
https://github.com/adam900710/linux/tree/rescue_changes

[BACKGROUND]
There is an adventurous user using btrfstune to convert a 32T btrfs
from crc32c to xxhash.

However for such huge fs, it takes too long time and the reporter
canceled the conversion.

This makes the reporter unable to mount the fs at all.

[CAUSE]
First of all, for a half converted fs, we will never allow RW mount, so
everything must be done in rescue mode.

There are several different stages of csum conversion, and at different
stage it requires different handling from kernel:

- Generationg new data csums
  At this stage only the super flags (CHANGING_DATA_CSUM flag) is
  preventing the kernel from mounting.

  Intrdoce "rescue=ignoresuperflags" to address this.

- Deleting old data cums
  The same super flags problem, with possible missing data csums.

  Despite the new "rescue=ignoresuperflags", end users will also need
  the existing "rescue=ignoredatacsums" mount option.

- Renaming the objectid of new data cums
  The new csums' objectid will be changed to the regular one.

  During this we can hit data csum mismatch.
  So the same "rescue=ignoresuperflags:ignoredatacsums" can handle it
  already.

- Rewriting metadata csums
  This part is done in-place (no COW), with a new super flags
  (CHANGING_META_CSUM).

  So here introduce a new "rescue=ignoremetacsums" to ignore the
  metadata checksum verification (and rely on the remaining sanity
  checks like tree-checkers).

The first 2 patches are just small cleanups, meanwhile the last two are
the new "rescue=" mount options to handle interrupted csum change.

Qu Wenruo (4):
  btrfs: remove unused Opt enums
  btrfs: output the unrecognized super flags as hex
  btrfs: introduce new "rescue=ignoremetacsums" mount option
  btrfs: introduce new "rescue=ignoresuperflags" mount option

 fs/btrfs/bio.c       |  2 +-
 fs/btrfs/disk-io.c   | 35 +++++++++++++++++++++++++----------
 fs/btrfs/file-item.c |  2 +-
 fs/btrfs/fs.h        |  5 ++++-
 fs/btrfs/messages.c  |  3 ++-
 fs/btrfs/super.c     | 27 +++++++++++++++++++++++----
 fs/btrfs/sysfs.c     |  2 ++
 fs/btrfs/zoned.c     |  2 +-
 8 files changed, 59 insertions(+), 19 deletions(-)

-- 
2.45.2

[PATCH v2 1/4] btrfs: remove unused Opt enums

[Qu Wenruo]

The following three Opt_* enums are not utilized at all:

- Opt_ignorebadroots
- Opt_ignoredatacsums
- Opt_rescue_all

All those enums are from the old day where we have dedicated mount
options, meanwhile nowadays they are all moved to "rescue=" mount option
groups, and no more global token for them.

So we can safely remove them now.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/super.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 549ad700e49e..902423f2839c 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -125,9 +125,6 @@ enum {
 	Opt_rescue,
 	Opt_usebackuproot,
 	Opt_nologreplay,
-	Opt_ignorebadroots,
-	Opt_ignoredatacsums,
-	Opt_rescue_all,
 
 	/* Debugging options */
 	Opt_enospc_debug,
-- 
2.45.2

[PATCH v2 2/4] btrfs: output the unrecognized super flags as hex

[Qu Wenruo]

Most of the extra suepr flags are beyond 32bits (from CHANGING_FSID_V2
to CHANGING_*_CSUMS), thus using %llu is not only too long and pretty
hard to read.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/disk-io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5870e76d20e2..92661d8ebf76 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2347,7 +2347,7 @@ int btrfs_validate_super(const struct btrfs_fs_info *fs_info,
 		ret = -EINVAL;
 	}
 	if (btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP) {
-		btrfs_err(fs_info, "unrecognized or unsupported super flag: %llu",
+		btrfs_err(fs_info, "unrecognized or unsupported super flag: 0x%llx",
 				btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP);
 		ret = -EINVAL;
 	}
-- 
2.45.2

[PATCH v2 3/4] btrfs: introduce new "rescue=ignoremetacsums" mount option

[Qu Wenruo]

This patch introduces "rescue=ignoremetacsums" to ignore metadata csums,
meanwhile all the other metadata sanity checks are still kept as is.

This new mount option is mostly to allow the kernel to mount an
interrupted checksum conversion (at the metadata csum overwrite stage).

And since the main part of metadata sanity checks is inside
tree-checker, we shouldn't lose much safety, and the new mount option is
rescue mount option it requires full read-only mount.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/bio.c       |  2 +-
 fs/btrfs/disk-io.c   | 19 +++++++++++++------
 fs/btrfs/file-item.c |  2 +-
 fs/btrfs/fs.h        |  4 +++-
 fs/btrfs/messages.c  |  3 ++-
 fs/btrfs/super.c     | 13 ++++++++++++-
 fs/btrfs/sysfs.c     |  1 +
 fs/btrfs/zoned.c     |  2 +-
 8 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
index e3a57196b0ee..1d063ab5018b 100644
--- a/fs/btrfs/bio.c
+++ b/fs/btrfs/bio.c
@@ -732,7 +732,7 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
 		 * point, so they are handled as part of the no-checksum case.
 		 */
 		if (inode && !(inode->flags & BTRFS_INODE_NODATASUM) &&
-		    !test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state) &&
+		    !test_bit(BTRFS_FS_STATE_NO_DATA_CSUMS, &fs_info->fs_state) &&
 		    !btrfs_is_data_reloc_root(inode->root)) {
 			if (should_async_write(bbio) &&
 			    btrfs_wq_submit_bio(bbio, bioc, &smap, mirror_num))
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 92661d8ebf76..e4e8e2a56cec 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -367,6 +367,7 @@ int btrfs_validate_extent_buffer(struct extent_buffer *eb,
 	u8 result[BTRFS_CSUM_SIZE];
 	const u8 *header_csum;
 	int ret = 0;
+	const bool ignore_csum = btrfs_test_opt(fs_info, IGNOREMETACSUMS);
 
 	ASSERT(check);
 
@@ -399,13 +400,17 @@ int btrfs_validate_extent_buffer(struct extent_buffer *eb,
 
 	if (memcmp(result, header_csum, csum_size) != 0) {
 		btrfs_warn_rl(fs_info,
-"checksum verify failed on logical %llu mirror %u wanted " CSUM_FMT " found " CSUM_FMT " level %d",
+		"checksum verify failed on logical %llu mirror %u wanted "
+		CSUM_FMT " found " CSUM_FMT " level %d%s",
 			      eb->start, eb->read_mirror,
 			      CSUM_FMT_VALUE(csum_size, header_csum),
 			      CSUM_FMT_VALUE(csum_size, result),
-			      btrfs_header_level(eb));
-		ret = -EUCLEAN;
-		goto out;
+			      btrfs_header_level(eb),
+			      ignore_csum ? ", ignoring" : "");
+		if (!ignore_csum) {
+			ret = -EUCLEAN;
+			goto out;
+		}
 	}
 
 	if (found_level != check->level) {
@@ -2131,7 +2136,7 @@ static int load_global_roots_objectid(struct btrfs_root *tree_root,
 	/* If we have IGNOREDATACSUMS skip loading these roots. */
 	if (objectid == BTRFS_CSUM_TREE_OBJECTID &&
 	    btrfs_test_opt(fs_info, IGNOREDATACSUMS)) {
-		set_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state);
+		set_bit(BTRFS_FS_STATE_NO_DATA_CSUMS, &fs_info->fs_state);
 		return 0;
 	}
 
@@ -2184,7 +2189,7 @@ static int load_global_roots_objectid(struct btrfs_root *tree_root,
 
 	if (!found || ret) {
 		if (objectid == BTRFS_CSUM_TREE_OBJECTID)
-			set_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state);
+			set_bit(BTRFS_FS_STATE_NO_DATA_CSUMS, &fs_info->fs_state);
 
 		if (!btrfs_test_opt(fs_info, IGNOREBADROOTS))
 			ret = ret ? ret : -ENOENT;
@@ -2865,6 +2870,8 @@ static int init_mount_fs_info(struct btrfs_fs_info *fs_info, struct super_block
 
 	if (sb_rdonly(sb))
 		set_bit(BTRFS_FS_STATE_RO, &fs_info->fs_state);
+	if (btrfs_test_opt(fs_info, IGNOREMETACSUMS))
+		set_bit(BTRFS_FS_STATE_SKIP_META_CSUMS, &fs_info->fs_state);
 
 	return btrfs_alloc_stripe_hash_table(fs_info);
 }
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 55703c833f3d..6c7713fb9a75 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -353,7 +353,7 @@ blk_status_t btrfs_lookup_bio_sums(struct btrfs_bio *bbio)
 	u32 bio_offset = 0;
 
 	if ((inode->flags & BTRFS_INODE_NODATASUM) ||
-	    test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
+	    test_bit(BTRFS_FS_STATE_NO_DATA_CSUMS, &fs_info->fs_state))
 		return BLK_STS_OK;
 
 	/*
diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
index 18e0d3539496..94faf83eb8d0 100644
--- a/fs/btrfs/fs.h
+++ b/fs/btrfs/fs.h
@@ -98,7 +98,8 @@ enum {
 	/* The btrfs_fs_info created for self-tests */
 	BTRFS_FS_STATE_DUMMY_FS_INFO,
 
-	BTRFS_FS_STATE_NO_CSUMS,
+	BTRFS_FS_STATE_NO_DATA_CSUMS,
+	BTRFS_FS_STATE_SKIP_META_CSUMS,
 
 	/* Indicates there was an error cleaning up a log tree. */
 	BTRFS_FS_STATE_LOG_CLEANUP_ERROR,
@@ -224,6 +225,7 @@ enum {
 	BTRFS_MOUNT_IGNOREDATACSUMS		= (1UL << 28),
 	BTRFS_MOUNT_NODISCARD			= (1UL << 29),
 	BTRFS_MOUNT_NOSPACECACHE		= (1UL << 30),
+	BTRFS_MOUNT_IGNOREMETACSUMS		= (1UL << 31),
 };
 
 /*
diff --git a/fs/btrfs/messages.c b/fs/btrfs/messages.c
index 210d9c82e2ae..77752eec125d 100644
--- a/fs/btrfs/messages.c
+++ b/fs/btrfs/messages.c
@@ -20,7 +20,8 @@ static const char fs_state_chars[] = {
 	[BTRFS_FS_STATE_TRANS_ABORTED]		= 'A',
 	[BTRFS_FS_STATE_DEV_REPLACING]		= 'R',
 	[BTRFS_FS_STATE_DUMMY_FS_INFO]		= 0,
-	[BTRFS_FS_STATE_NO_CSUMS]		= 'C',
+	[BTRFS_FS_STATE_NO_DATA_CSUMS]		= 'C',
+	[BTRFS_FS_STATE_SKIP_META_CSUMS]	= 'S',
 	[BTRFS_FS_STATE_LOG_CLEANUP_ERROR]	= 'L',
 };
 
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 902423f2839c..386500b9b440 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -175,6 +175,7 @@ enum {
 	Opt_rescue_nologreplay,
 	Opt_rescue_ignorebadroots,
 	Opt_rescue_ignoredatacsums,
+	Opt_rescue_ignoremetacsums,
 	Opt_rescue_parameter_all,
 };
 
@@ -184,7 +185,9 @@ static const struct constant_table btrfs_parameter_rescue[] = {
 	{ "ignorebadroots", Opt_rescue_ignorebadroots },
 	{ "ibadroots", Opt_rescue_ignorebadroots },
 	{ "ignoredatacsums", Opt_rescue_ignoredatacsums },
+	{ "ignoremetacsums", Opt_rescue_ignoremetacsums},
 	{ "idatacsums", Opt_rescue_ignoredatacsums },
+	{ "imetacsums", Opt_rescue_ignoremetacsums},
 	{ "all", Opt_rescue_parameter_all },
 	{}
 };
@@ -570,8 +573,12 @@ static int btrfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		case Opt_rescue_ignoredatacsums:
 			btrfs_set_opt(ctx->mount_opt, IGNOREDATACSUMS);
 			break;
+		case Opt_rescue_ignoremetacsums:
+			btrfs_set_opt(ctx->mount_opt, IGNOREMETACSUMS);
+			break;
 		case Opt_rescue_parameter_all:
 			btrfs_set_opt(ctx->mount_opt, IGNOREDATACSUMS);
+			btrfs_set_opt(ctx->mount_opt, IGNOREMETACSUMS);
 			btrfs_set_opt(ctx->mount_opt, IGNOREBADROOTS);
 			btrfs_set_opt(ctx->mount_opt, NOLOGREPLAY);
 			break;
@@ -646,7 +653,8 @@ bool btrfs_check_options(const struct btrfs_fs_info *info, unsigned long *mount_
 	if (!(flags & SB_RDONLY) &&
 	    (check_ro_option(info, *mount_opt, BTRFS_MOUNT_NOLOGREPLAY, "nologreplay") ||
 	     check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREBADROOTS, "ignorebadroots") ||
-	     check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREDATACSUMS, "ignoredatacsums")))
+	     check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREDATACSUMS, "ignoredatacsums") ||
+	     check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREMETACSUMS, "ignoremetacsums")))
 		ret = false;
 
 	if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE) &&
@@ -1062,6 +1070,8 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 		print_rescue_option(seq, "ignorebadroots", &printed);
 	if (btrfs_test_opt(info, IGNOREDATACSUMS))
 		print_rescue_option(seq, "ignoredatacsums", &printed);
+	if (btrfs_test_opt(info, IGNOREMETACSUMS))
+		print_rescue_option(seq, "ignoremetacsums", &printed);
 	if (btrfs_test_opt(info, FLUSHONCOMMIT))
 		seq_puts(seq, ",flushoncommit");
 	if (btrfs_test_opt(info, DISCARD_SYNC))
@@ -1419,6 +1429,7 @@ static void btrfs_emit_options(struct btrfs_fs_info *info,
 	btrfs_info_if_set(info, old, USEBACKUPROOT, "trying to use backup root at mount time");
 	btrfs_info_if_set(info, old, IGNOREBADROOTS, "ignoring bad roots");
 	btrfs_info_if_set(info, old, IGNOREDATACSUMS, "ignoring data csums");
+	btrfs_info_if_set(info, old, IGNOREMETACSUMS, "ignoring meta csums");
 
 	btrfs_info_if_unset(info, old, NODATACOW, "setting datacow");
 	btrfs_info_if_unset(info, old, SSD, "not using ssd optimizations");
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index af545b6b1190..91e47a3fbedb 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -385,6 +385,7 @@ static const char *rescue_opts[] = {
 	"nologreplay",
 	"ignorebadroots",
 	"ignoredatacsums",
+	"ignoremetacsums",
 	"all",
 };
 
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 992a5b7756ca..386daea0ca0b 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1844,7 +1844,7 @@ void btrfs_finish_ordered_zoned(struct btrfs_ordered_extent *ordered)
 	 * here so that we don't attempt to log the csums later.
 	 */
 	if ((inode->flags & BTRFS_INODE_NODATASUM) ||
-	    test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state)) {
+	    test_bit(BTRFS_FS_STATE_NO_DATA_CSUMS, &fs_info->fs_state)) {
 		while ((sum = list_first_entry_or_null(&ordered->list,
 						       typeof(*sum), list))) {
 			list_del(&sum->list);
-- 
2.45.2

[PATCH v2 4/4] btrfs: introduce new "rescue=ignoresuperflags" mount option

[Qu Wenruo]

This new mount option would allow the kernel to skip the super flags
check, it's mostly to allow the kernel to do a rescue mount of an
interrupted checksum conversion.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/disk-io.c | 16 ++++++++++++----
 fs/btrfs/fs.h      |  1 +
 fs/btrfs/super.c   | 13 ++++++++++++-
 fs/btrfs/sysfs.c   |  1 +
 4 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e4e8e2a56cec..723ea765a05c 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2346,15 +2346,23 @@ int btrfs_validate_super(const struct btrfs_fs_info *fs_info,
 	u64 nodesize = btrfs_super_nodesize(sb);
 	u64 sectorsize = btrfs_super_sectorsize(sb);
 	int ret = 0;
+	const bool ignore_flags = btrfs_test_opt(fs_info, IGNORESUPERFLAGS);
 
 	if (btrfs_super_magic(sb) != BTRFS_MAGIC) {
 		btrfs_err(fs_info, "no valid FS found");
 		ret = -EINVAL;
 	}
-	if (btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP) {
-		btrfs_err(fs_info, "unrecognized or unsupported super flag: 0x%llx",
-				btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP);
-		ret = -EINVAL;
+	if ((btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP)) {
+		if (!ignore_flags) {
+			btrfs_err(fs_info,
+			"unrecognized or unsupported super flag: 0x%llx",
+				  btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP);
+			ret = -EINVAL;
+		} else {
+			btrfs_info(fs_info,
+			"unrecognized or unsupported super flags: 0x%llx, ignoring",
+				   btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP);
+		}
 	}
 	if (btrfs_super_root_level(sb) >= BTRFS_MAX_LEVEL) {
 		btrfs_err(fs_info, "tree_root level too big: %d >= %d",
diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
index 94faf83eb8d0..5939821dd743 100644
--- a/fs/btrfs/fs.h
+++ b/fs/btrfs/fs.h
@@ -226,6 +226,7 @@ enum {
 	BTRFS_MOUNT_NODISCARD			= (1UL << 29),
 	BTRFS_MOUNT_NOSPACECACHE		= (1UL << 30),
 	BTRFS_MOUNT_IGNOREMETACSUMS		= (1UL << 31),
+	BTRFS_MOUNT_IGNORESUPERFLAGS		= (1UL << 32),
 };
 
 /*
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 386500b9b440..a66b5c901510 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -176,6 +176,7 @@ enum {
 	Opt_rescue_ignorebadroots,
 	Opt_rescue_ignoredatacsums,
 	Opt_rescue_ignoremetacsums,
+	Opt_rescue_ignoresuperflags,
 	Opt_rescue_parameter_all,
 };
 
@@ -186,8 +187,10 @@ static const struct constant_table btrfs_parameter_rescue[] = {
 	{ "ibadroots", Opt_rescue_ignorebadroots },
 	{ "ignoredatacsums", Opt_rescue_ignoredatacsums },
 	{ "ignoremetacsums", Opt_rescue_ignoremetacsums},
+	{ "ignoresuperflags", Opt_rescue_ignoresuperflags},
 	{ "idatacsums", Opt_rescue_ignoredatacsums },
 	{ "imetacsums", Opt_rescue_ignoremetacsums},
+	{ "isuperflags", Opt_rescue_ignoresuperflags},
 	{ "all", Opt_rescue_parameter_all },
 	{}
 };
@@ -576,9 +579,13 @@ static int btrfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		case Opt_rescue_ignoremetacsums:
 			btrfs_set_opt(ctx->mount_opt, IGNOREMETACSUMS);
 			break;
+		case Opt_rescue_ignoresuperflags:
+			btrfs_set_opt(ctx->mount_opt, IGNORESUPERFLAGS);
+			break;
 		case Opt_rescue_parameter_all:
 			btrfs_set_opt(ctx->mount_opt, IGNOREDATACSUMS);
 			btrfs_set_opt(ctx->mount_opt, IGNOREMETACSUMS);
+			btrfs_set_opt(ctx->mount_opt, IGNORESUPERFLAGS);
 			btrfs_set_opt(ctx->mount_opt, IGNOREBADROOTS);
 			btrfs_set_opt(ctx->mount_opt, NOLOGREPLAY);
 			break;
@@ -654,7 +661,8 @@ bool btrfs_check_options(const struct btrfs_fs_info *info, unsigned long *mount_
 	    (check_ro_option(info, *mount_opt, BTRFS_MOUNT_NOLOGREPLAY, "nologreplay") ||
 	     check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREBADROOTS, "ignorebadroots") ||
 	     check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREDATACSUMS, "ignoredatacsums") ||
-	     check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREMETACSUMS, "ignoremetacsums")))
+	     check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREMETACSUMS, "ignoremetacsums") ||
+	     check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNORESUPERFLAGS, "ignoresuperflags")))
 		ret = false;
 
 	if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE) &&
@@ -1072,6 +1080,8 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 		print_rescue_option(seq, "ignoredatacsums", &printed);
 	if (btrfs_test_opt(info, IGNOREMETACSUMS))
 		print_rescue_option(seq, "ignoremetacsums", &printed);
+	if (btrfs_test_opt(info, IGNORESUPERFLAGS))
+		print_rescue_option(seq, "ignoresuperflags", &printed);
 	if (btrfs_test_opt(info, FLUSHONCOMMIT))
 		seq_puts(seq, ",flushoncommit");
 	if (btrfs_test_opt(info, DISCARD_SYNC))
@@ -1430,6 +1440,7 @@ static void btrfs_emit_options(struct btrfs_fs_info *info,
 	btrfs_info_if_set(info, old, IGNOREBADROOTS, "ignoring bad roots");
 	btrfs_info_if_set(info, old, IGNOREDATACSUMS, "ignoring data csums");
 	btrfs_info_if_set(info, old, IGNOREMETACSUMS, "ignoring meta csums");
+	btrfs_info_if_set(info, old, IGNORESUPERFLAGS, "ignoring unknown super flags");
 
 	btrfs_info_if_unset(info, old, NODATACOW, "setting datacow");
 	btrfs_info_if_unset(info, old, SSD, "not using ssd optimizations");
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 91e47a3fbedb..94bff7f0f0c4 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -386,6 +386,7 @@ static const char *rescue_opts[] = {
 	"ignorebadroots",
 	"ignoredatacsums",
 	"ignoremetacsums",
+	"ignoresuperflags",
 	"all",
 };
 
-- 
2.45.2

Re: [PATCH v2 4/4] btrfs: introduce new "rescue=ignoresuperflags" mount option

[Geert Uytterhoeven]

 	Hi Qu,

On Fri, 14 Jun 2024, Qu Wenruo wrote:
> This new mount option would allow the kernel to skip the super flags
> check, it's mostly to allow the kernel to do a rescue mount of an
> interrupted checksum conversion.
>
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Qu Wenruo <wqu@suse.com>

Thanks for your patch, which is now commit cbc2bc70b8c22974 ("btrfs:
introduce new "rescue=ignoresuperflags" mount option") in next-20240709.

> --- a/fs/btrfs/fs.h
> +++ b/fs/btrfs/fs.h
> @@ -226,6 +226,7 @@ enum {
> 	BTRFS_MOUNT_NODISCARD			= (1UL << 29),
> 	BTRFS_MOUNT_NOSPACECACHE		= (1UL << 30),
> 	BTRFS_MOUNT_IGNOREMETACSUMS		= (1UL << 31),
> +	BTRFS_MOUNT_IGNORESUPERFLAGS		= (1UL << 32),

"1UL" was changed to "1ULL" while applying, but that is not sufficient,
as all other mount flags handling still operates on "unsigned long",
which is 32-bit ont 32-bit platforms.

Hence noreply@ellerman.id.au reported several build failures on 32-bit
platforms (e.g. m68k[1]):

     fs/btrfs/super.c:666:48: error: conversion from 'enum <anonymous>' to 'long unsigned int' changes value from '4294967296' to '0' [-Werror=overflow]

[1] http://kisskb.ellerman.id.au/kisskb/buildresult/15197832/

Gr{oetje,eeting}s,

 						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
 							    -- Linus Torvalds