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Message-ID: <20230904045742.827584-1-dongyangli@ddn.com>
Date: Mon, 4 Sep 2023 14:57:42 +1000
From: Li Dongyang <dongyangli@....com>
To: linux-ext4@...r.kernel.org
Cc: adilger@...ger.ca
Subject: [PATCH] e2fsck: check all sparse_super backups
From: Andreas Dilger <adilger@...mcloud.com>
Teach e2fsck to look for backup super blocks in the "sparse_super"
groups, by checking group #1 first and then powers of 3^n, 5^n,
and 7^n, up to the limit of available block groups.
Export ext2fs_list_backups() function to efficiently iterate groups
for backup sb/GDT instead of checking every group. Ensure that the
group counters do not try to overflow the 2^32-1 group limit, and
try to limit scanning to the size of the block device (if available).
Signed-off-by: Li Dongyang <dongyangli@....com>
Signed-off-by: Andreas Dilger <adilger@...mcloud.com>
---
e2fsck/util.c | 77 +++++++++++++++++++-----------------
lib/ext2fs/ext2fs.h | 2 +
lib/ext2fs/res_gdt.c | 34 ++++++++++------
tests/f_boundscheck/expect.1 | 1 -
tests/f_boundscheck/expect.2 | 1 -
5 files changed, 64 insertions(+), 51 deletions(-)
diff --git a/e2fsck/util.c b/e2fsck/util.c
index 0fe436031..6982966e6 100644
--- a/e2fsck/util.c
+++ b/e2fsck/util.c
@@ -560,29 +560,20 @@ blk64_t get_backup_sb(e2fsck_t ctx, ext2_filsys fs, const char *name,
struct ext2_super_block *sb;
io_channel io = NULL;
void *buf = NULL;
- int blocksize;
- blk64_t superblock, ret_sb = 8193;
+ int blocksize = EXT2_MIN_BLOCK_SIZE;
+ int blocksize_known = 0;
+ blk_t bpg = 0;
+ blk64_t ret_sb = 8193;
if (fs && fs->super) {
- ret_sb = (fs->super->s_blocks_per_group +
- fs->super->s_first_data_block);
- if (ctx) {
- ctx->superblock = ret_sb;
- ctx->blocksize = fs->blocksize;
- }
- return ret_sb;
+ blocksize = fs->blocksize;
+ blocksize_known = 1;
+ bpg = fs->super->s_blocks_per_group;
}
- if (ctx) {
- if (ctx->blocksize) {
- ret_sb = ctx->blocksize * 8;
- if (ctx->blocksize == 1024)
- ret_sb++;
- ctx->superblock = ret_sb;
- return ret_sb;
- }
- ctx->superblock = ret_sb;
- ctx->blocksize = 1024;
+ if (ctx && ctx->blocksize) {
+ blocksize = ctx->blocksize;
+ blocksize_known = 1;
}
if (!name || !manager)
@@ -595,28 +586,42 @@ blk64_t get_backup_sb(e2fsck_t ctx, ext2_filsys fs, const char *name,
goto cleanup;
sb = (struct ext2_super_block *) buf;
- for (blocksize = EXT2_MIN_BLOCK_SIZE;
- blocksize <= EXT2_MAX_BLOCK_SIZE ; blocksize *= 2) {
- superblock = blocksize*8;
- if (blocksize == 1024)
- superblock++;
+ for (; blocksize <= EXT2_MAX_BLOCK_SIZE; blocksize *= 2) {
+ dgrp_t grp, three = 1, five = 5, seven = 7;
+ dgrp_t limit = (dgrp_t)-1;
+ blk_t this_bpg = bpg ? bpg : blocksize * 8;
+
+ if (ctx->num_blocks && limit > ctx->num_blocks / this_bpg)
+ limit = ctx->num_blocks / this_bpg;
+
io_channel_set_blksize(io, blocksize);
- if (io_channel_read_blk64(io, superblock,
- -SUPERBLOCK_SIZE, buf))
- continue;
+
+ while ((grp = ext2fs_list_backups(NULL, &three,
+ &five, &seven)) < limit) {
+ blk64_t superblock = (blk64_t)grp * this_bpg;
+
+ if (blocksize == 1024)
+ superblock++;
+ if (io_channel_read_blk64(io, superblock,
+ -SUPERBLOCK_SIZE, buf))
+ continue;
#ifdef WORDS_BIGENDIAN
- if (sb->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
- ext2fs_swap_super(sb);
+ if (sb->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC))
+ ext2fs_swap_super(sb);
#endif
- if ((sb->s_magic == EXT2_SUPER_MAGIC) &&
- (EXT2_BLOCK_SIZE(sb) == blocksize)) {
- ret_sb = superblock;
- if (ctx) {
- ctx->superblock = superblock;
- ctx->blocksize = blocksize;
+ if ((sb->s_magic == EXT2_SUPER_MAGIC) &&
+ (EXT2_BLOCK_SIZE(sb) == blocksize)) {
+ ret_sb = superblock;
+ if (ctx) {
+ ctx->superblock = superblock;
+ ctx->blocksize = blocksize;
+ }
+ goto cleanup;
}
- break;
}
+
+ if (blocksize_known)
+ break;
}
cleanup:
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 72c60d2b5..7f3f6794a 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -1483,6 +1483,8 @@ errcode_t ext2fs_convert_subcluster_bitmap(ext2_filsys fs,
ext2fs_block_bitmap *bitmap);
errcode_t ext2fs_count_used_clusters(ext2_filsys fs, blk64_t start,
blk64_t end, blk64_t *out);
+extern unsigned int ext2fs_list_backups(ext2_filsys fs, unsigned int *three,
+ unsigned int *five, unsigned int *seven);
/* get_num_dirs.c */
extern errcode_t ext2fs_get_num_dirs(ext2_filsys fs, ext2_ino_t *ret_num_dirs);
diff --git a/lib/ext2fs/res_gdt.c b/lib/ext2fs/res_gdt.c
index fa8d8d6be..e4e290bba 100644
--- a/lib/ext2fs/res_gdt.c
+++ b/lib/ext2fs/res_gdt.c
@@ -20,18 +20,19 @@
/*
* Iterate through the groups which hold BACKUP superblock/GDT copies in an
* ext3 filesystem. The counters should be initialized to 1, 5, and 7 before
- * calling this for the first time. In a sparse filesystem it will be the
- * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
+ * calling this for the first time. In a sparse_super filesystem it will be
+ * the sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
* For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
+ * For a sparse_super2 filesystem there are two backups in specific groups.
*/
-static unsigned int list_backups(ext2_filsys fs, unsigned int *three,
- unsigned int *five, unsigned int *seven)
+dgrp_t ext2fs_list_backups(ext2_filsys fs, dgrp_t *three,
+ dgrp_t *five, dgrp_t *seven)
{
- unsigned int *min = three;
- int mult = 3;
- unsigned int ret;
+ dgrp_t *min = three;
+ unsigned long long mult = 3;
+ dgrp_t ret;
- if (ext2fs_has_feature_sparse_super2(fs->super)) {
+ if (fs && ext2fs_has_feature_sparse_super2(fs->super)) {
if (*min == 1) {
*min += 1;
if (fs->super->s_backup_bgs[0])
@@ -42,11 +43,14 @@ static unsigned int list_backups(ext2_filsys fs, unsigned int *three,
if (fs->super->s_backup_bgs[1])
return fs->super->s_backup_bgs[1];
}
+
return fs->group_desc_count;
}
- if (!ext2fs_has_feature_sparse_super(fs->super)) {
+
+ if (fs && !ext2fs_has_feature_sparse_super(fs->super)) {
ret = *min;
*min += 1;
+
return ret;
}
@@ -60,7 +64,11 @@ static unsigned int list_backups(ext2_filsys fs, unsigned int *three,
}
ret = *min;
- *min *= mult;
+ mult *= *min;
+ if (mult > (dgrp_t)-1)
+ *min = (dgrp_t)-1;
+ else
+ *min = mult;
return ret;
}
@@ -142,8 +150,8 @@ errcode_t ext2fs_create_resize_inode(ext2_filsys fs)
gdt_blk = sb_blk + 1 + fs->desc_blocks;
rsv_off < sb->s_reserved_gdt_blocks;
rsv_off++, gdt_off++, gdt_blk++) {
- unsigned int three = 1, five = 5, seven = 7;
- unsigned int grp, last = 0;
+ dgrp_t three = 1, five = 5, seven = 7;
+ dgrp_t grp, last = 0;
int gdt_dirty = 0;
gdt_off %= apb;
@@ -183,7 +191,7 @@ errcode_t ext2fs_create_resize_inode(ext2_filsys fs)
goto out_dindir;
}
- while ((grp = list_backups(fs, &three, &five, &seven)) <
+ while ((grp = ext2fs_list_backups(fs, &three, &five, &seven)) <
fs->group_desc_count) {
blk_t expect = gdt_blk + grp * sb->s_blocks_per_group;
diff --git a/tests/f_boundscheck/expect.1 b/tests/f_boundscheck/expect.1
index c2170b8f9..5c9ead485 100644
--- a/tests/f_boundscheck/expect.1
+++ b/tests/f_boundscheck/expect.1
@@ -1,6 +1,5 @@
ext2fs_check_desc: Corrupt group descriptor: bad block for inode table
../e2fsck/e2fsck: Group descriptors look bad... trying backup blocks...
-../e2fsck/e2fsck: Bad magic number in super-block while using the backup blocks../e2fsck/e2fsck: going back to original superblock
Note: if several inode or block bitmap blocks or part
of the inode table require relocation, you may wish to try
running e2fsck with the '-b 8193' option first. The problem
diff --git a/tests/f_boundscheck/expect.2 b/tests/f_boundscheck/expect.2
index c2170b8f9..5c9ead485 100644
--- a/tests/f_boundscheck/expect.2
+++ b/tests/f_boundscheck/expect.2
@@ -1,6 +1,5 @@
ext2fs_check_desc: Corrupt group descriptor: bad block for inode table
../e2fsck/e2fsck: Group descriptors look bad... trying backup blocks...
-../e2fsck/e2fsck: Bad magic number in super-block while using the backup blocks../e2fsck/e2fsck: going back to original superblock
Note: if several inode or block bitmap blocks or part
of the inode table require relocation, you may wish to try
running e2fsck with the '-b 8193' option first. The problem
--
2.41.0
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