f2fs: use EINVAL for superblock with invalid magic

The kernel mount_block_root() function expects -EACESS or -EINVAL for a
unmountable filesystem when trying to mount the root with different
filesystem types.

However, in 5.3-rc1 the behavior when F2FS code cannot find valid block
changed to return -EFSCORRUPTED(-EUCLEAN), and this error code makes
mount_block_root() fail when trying to probe F2FS.

When the magic number of the superblock mismatches, it has a high
probability that it's just not a F2FS. In this case return -EINVAL seems
to be a better result, and this return value can make mount_block_root()
probing work again.

Return -EINVAL when the superblock has magic mismatch, -EFSCORRUPTED in
other cases (the magic matches but the superblock cannot be recognized).

Fixes: 10f966bbf521 ("f2fs: use generic EFSBADCRC/EFSCORRUPTED")
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 24 insertions, 24 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index d95a681ef7c9..1838dd852a50 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2422,6 +2422,12 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
         size_t crc_offset = 0;
         __u32 crc = 0;
 
+        if (le32_to_cpu(raw_super->magic) != F2FS_SUPER_MAGIC) {
+                f2fs_info(sbi, "Magic Mismatch, valid(0x%x) - read(0x%x)",
+                          F2FS_SUPER_MAGIC, le32_to_cpu(raw_super->magic));
+                return -EINVAL;
+        }
+
         /* Check checksum_offset and crc in superblock */
         if (__F2FS_HAS_FEATURE(raw_super, F2FS_FEATURE_SB_CHKSUM)) {
                 crc_offset = le32_to_cpu(raw_super->checksum_offset);
@@ -2429,26 +2435,20 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
                         offsetof(struct f2fs_super_block, crc)) {
                         f2fs_info(sbi, "Invalid SB checksum offset: %zu",
                                   crc_offset);
-                        return 1;
+                        return -EFSCORRUPTED;
                 }
                 crc = le32_to_cpu(raw_super->crc);
                 if (!f2fs_crc_valid(sbi, crc, raw_super, crc_offset)) {
                         f2fs_info(sbi, "Invalid SB checksum value: %u", crc);
-                        return 1;
+                        return -EFSCORRUPTED;
                 }
         }
 
-        if (F2FS_SUPER_MAGIC != le32_to_cpu(raw_super->magic)) {
-                f2fs_info(sbi, "Magic Mismatch, valid(0x%x) - read(0x%x)",
-                          F2FS_SUPER_MAGIC, le32_to_cpu(raw_super->magic));
-                return 1;
-        }
-
         /* Currently, support only 4KB page cache size */
         if (F2FS_BLKSIZE != PAGE_SIZE) {
                 f2fs_info(sbi, "Invalid page_cache_size (%lu), supports only 4KB",
                           PAGE_SIZE);
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         /* Currently, support only 4KB block size */
@@ -2456,14 +2456,14 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
         if (blocksize != F2FS_BLKSIZE) {
                 f2fs_info(sbi, "Invalid blocksize (%u), supports only 4KB",
                           blocksize);
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         /* check log blocks per segment */
         if (le32_to_cpu(raw_super->log_blocks_per_seg) != 9) {
                 f2fs_info(sbi, "Invalid log blocks per segment (%u)",
                           le32_to_cpu(raw_super->log_blocks_per_seg));
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         /* Currently, support 512/1024/2048/4096 bytes sector size */
@@ -2473,7 +2473,7 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
                                 F2FS_MIN_LOG_SECTOR_SIZE) {
                 f2fs_info(sbi, "Invalid log sectorsize (%u)",
                           le32_to_cpu(raw_super->log_sectorsize));
-                return 1;
+                return -EFSCORRUPTED;
         }
         if (le32_to_cpu(raw_super->log_sectors_per_block) +
                 le32_to_cpu(raw_super->log_sectorsize) !=
@@ -2481,7 +2481,7 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
                 f2fs_info(sbi, "Invalid log sectors per block(%u) log sectorsize(%u)",
                           le32_to_cpu(raw_super->log_sectors_per_block),
                           le32_to_cpu(raw_super->log_sectorsize));
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         segment_count = le32_to_cpu(raw_super->segment_count);
@@ -2495,7 +2495,7 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
         if (segment_count > F2FS_MAX_SEGMENT ||
                                 segment_count < F2FS_MIN_SEGMENTS) {
                 f2fs_info(sbi, "Invalid segment count (%u)", segment_count);
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         if (total_sections > segment_count ||
@@ -2503,25 +2503,25 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
                         segs_per_sec > segment_count || !segs_per_sec) {
                 f2fs_info(sbi, "Invalid segment/section count (%u, %u x %u)",
                           segment_count, total_sections, segs_per_sec);
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         if ((segment_count / segs_per_sec) < total_sections) {
                 f2fs_info(sbi, "Small segment_count (%u < %u * %u)",
                           segment_count, segs_per_sec, total_sections);
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         if (segment_count > (le64_to_cpu(raw_super->block_count) >> 9)) {
                 f2fs_info(sbi, "Wrong segment_count / block_count (%u > %llu)",
                           segment_count, le64_to_cpu(raw_super->block_count));
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         if (secs_per_zone > total_sections || !secs_per_zone) {
                 f2fs_info(sbi, "Wrong secs_per_zone / total_sections (%u, %u)",
                           secs_per_zone, total_sections);
-                return 1;
+                return -EFSCORRUPTED;
         }
         if (le32_to_cpu(raw_super->extension_count) > F2FS_MAX_EXTENSION ||
                         raw_super->hot_ext_count > F2FS_MAX_EXTENSION ||
@@ -2531,7 +2531,7 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
                           le32_to_cpu(raw_super->extension_count),
                           raw_super->hot_ext_count,
                           F2FS_MAX_EXTENSION);
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         if (le32_to_cpu(raw_super->cp_payload) >
@@ -2539,7 +2539,7 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
                 f2fs_info(sbi, "Insane cp_payload (%u > %u)",
                           le32_to_cpu(raw_super->cp_payload),
                           blocks_per_seg - F2FS_CP_PACKS);
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         /* check reserved ino info */
@@ -2550,12 +2550,12 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
                           le32_to_cpu(raw_super->node_ino),
                           le32_to_cpu(raw_super->meta_ino),
                           le32_to_cpu(raw_super->root_ino));
-                return 1;
+                return -EFSCORRUPTED;
         }
 
         /* check CP/SIT/NAT/SSA/MAIN_AREA area boundary */
         if (sanity_check_area_boundary(sbi, bh))
-                return 1;
+                return -EFSCORRUPTED;
 
         return 0;
 }
@@ -2872,10 +2872,10 @@ static int read_raw_super_block(struct f2fs_sb_info *sbi,
                 }
 
                 /* sanity checking of raw super */
-                if (sanity_check_raw_super(sbi, bh)) {
+                err = sanity_check_raw_super(sbi, bh);
+                if (err) {
                         f2fs_err(sbi, "Can't find valid F2FS filesystem in %dth superblock",
                                  block + 1);
-                        err = -EFSCORRUPTED;
                         brelse(bh);
                         continue;
                 }