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Message-Id: <20171204193530.54888-5-artem.blagodarenko@gmail.com>
Date: Mon, 4 Dec 2017 22:35:30 +0300
From: Artem Blagodarenko <artem.blagodarenko@...il.com>
To: linux-ext4@...r.kernel.org
Cc: adilger.kernel@...ger.ca
Subject: [PATCH v3 4/4] ext2fs: automaticlly open backup superblocks
e2image and e2fsck automatically try to open some backup superblocks,
if only blocksize is set or passed superblock can't be opened.
Try few backup superblocks (e.g. {1, 3, 5,7, 9} * blocksize * 8).
This code is moved to library.
Signed-off-by: Artem Blagodarenko <artem.blagodarenko@...il.com>
---
e2fsck/e2fsck.h | 2 -
e2fsck/message.c | 3 +-
e2fsck/unix.c | 16 ++++++--
e2fsck/util.c | 73 ---------------------------------
lib/ext2fs/ext2fs.h | 8 ++++
lib/ext2fs/openfs.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++++
misc/e2image.c | 10 ++++-
7 files changed, 146 insertions(+), 82 deletions(-)
diff --git a/e2fsck/e2fsck.h b/e2fsck/e2fsck.h
index 9eee4bc2..9cd3910e 100644
--- a/e2fsck/e2fsck.h
+++ b/e2fsck/e2fsck.h
@@ -634,8 +634,6 @@ extern void e2fsck_write_inode_full(e2fsck_t ctx, unsigned long ino,
#ifdef MTRACE
extern void mtrace_print(char *mesg);
#endif
-extern blk64_t get_backup_sb(e2fsck_t ctx, ext2_filsys fs,
- const char *name, io_manager manager);
extern int ext2_file_type(unsigned int mode);
extern int write_all(int fd, char *buf, size_t count);
void dump_mmp_msg(struct mmp_struct *mmp, const char *msg);
diff --git a/e2fsck/message.c b/e2fsck/message.c
index 727f71d5..df408917 100644
--- a/e2fsck/message.c
+++ b/e2fsck/message.c
@@ -465,7 +465,8 @@ static _INLINE_ void expand_percent_expression(FILE *f, ext2_filsys fs,
fprintf(f, "%*lld", width, (long long) ctx->blkcount);
break;
case 'S':
- fprintf(f, "%llu", get_backup_sb(NULL, fs, NULL, NULL));
+ fprintf(f, "%llu", ext2fs_first_backup_sb(NULL, NULL, fs,
+ NULL, NULL));
break;
case 's':
fprintf(f, "%*s", width, ctx->str ? ctx->str : "NULL");
diff --git a/e2fsck/unix.c b/e2fsck/unix.c
index 2865f37a..888a2fce 100644
--- a/e2fsck/unix.c
+++ b/e2fsck/unix.c
@@ -1471,11 +1471,19 @@ restart:
retval ? _("Superblock invalid,") :
_("Group descriptors look bad..."));
orig_superblock = ctx->superblock;
- get_backup_sb(ctx, fs, ctx->filesystem_name, io_ptr);
- if (fs)
- ext2fs_close_free(&fs);
orig_retval = retval;
- retval = try_open_fs(ctx, flags, io_ptr, &fs);
+ retval = ext2fs_try_backups(ctx->filesystem_name,
+ ctx->io_options,
+ flags,
+ &ctx->superblock,
+ &ctx->blocksize, io_ptr,
+ &fs);
+ if (retval == 0) {
+ fs->priv_data = ctx;
+ e2fsck_set_bitmap_type(fs,
+ EXT2FS_BMAP64_RBTREE,
+ "default", NULL);
+ }
if ((orig_retval == 0) && retval != 0) {
if (fs)
ext2fs_close_free(&fs);
diff --git a/e2fsck/util.c b/e2fsck/util.c
index ed947025..b1c638c5 100644
--- a/e2fsck/util.c
+++ b/e2fsck/util.c
@@ -548,79 +548,6 @@ void mtrace_print(char *mesg)
}
#endif
-blk64_t get_backup_sb(e2fsck_t ctx, ext2_filsys fs, const char *name,
- io_manager manager)
-{
- struct ext2_super_block *sb;
- io_channel io = NULL;
- void *buf = NULL;
- int blocksize;
- blk64_t superblock, 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;
- }
-
- 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 (!name || !manager)
- goto cleanup;
-
- if (manager->open(name, 0, &io) != 0)
- goto cleanup;
-
- if (ext2fs_get_mem(SUPERBLOCK_SIZE, &buf))
- 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++;
- io_channel_set_blksize(io, blocksize);
- 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);
-#endif
- if ((sb->s_magic == EXT2_SUPER_MAGIC) &&
- (EXT2_BLOCK_SIZE(sb) == blocksize)) {
- ret_sb = superblock;
- if (ctx) {
- ctx->superblock = superblock;
- ctx->blocksize = blocksize;
- }
- break;
- }
- }
-
-cleanup:
- if (io)
- io_channel_close(io);
- if (buf)
- ext2fs_free_mem(&buf);
- return (ret_sb);
-}
-
/*
* Given a mode, return the ext2 file type
*/
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 6774e32c..942b46ea 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -1584,6 +1584,14 @@ extern int ext2fs_journal_sb_start(int blocksize);
extern errcode_t ext2fs_open(const char *name, int flags, int superblock,
unsigned int block_size, io_manager manager,
ext2_filsys *ret_fs);
+extern blk64_t ext2fs_first_backup_sb(blk64_t *superblock,
+ unsigned int *blocksize,
+ ext2_filsys fs, const char *name,
+ io_manager manager);
+extern errcode_t ext2fs_try_backups(const char *name, const char *io_options,
+ int flags, blk64_t *superblock,
+ unsigned int *block_size,
+ io_manager manager, ext2_filsys *ret_fs);
extern errcode_t ext2fs_open2(const char *name, const char *io_options,
int flags, int superblock,
unsigned int block_size, io_manager manager,
diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index 585ad766..d0e1d3bd 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -497,6 +497,122 @@ cleanup:
return retval;
}
+blk64_t ext2fs_first_backup_sb(blk64_t *superblock, unsigned int *block_size,
+ ext2_filsys fs, const char *name,
+ io_manager manager)
+{
+ struct ext2_super_block *sb;
+ io_channel io = NULL;
+ void *buf = NULL;
+ int try_blocksize;
+ blk64_t try_superblock, ret_sb = 8193;
+
+ if (fs && fs->super) {
+ ret_sb = (fs->super->s_blocks_per_group +
+ fs->super->s_first_data_block);
+ *superblock = ret_sb;
+ *block_size = fs->blocksize;
+ return ret_sb;
+ }
+
+ if (*block_size) {
+ ret_sb = *block_size * 8;
+ if (*block_size == 1024)
+ ret_sb++;
+ *superblock = ret_sb;
+ return ret_sb;
+ }
+
+ *superblock = ret_sb;
+ *block_size = 1024;
+
+ if (!name || !manager)
+ goto cleanup;
+
+ if (manager->open(name, 0, &io) != 0)
+ goto cleanup;
+
+ if (ext2fs_get_mem(SUPERBLOCK_SIZE, &buf))
+ goto cleanup;
+ sb = (struct ext2_super_block *) buf;
+
+ for (try_blocksize = EXT2_MIN_BLOCK_SIZE;
+ try_blocksize <= EXT2_MAX_BLOCK_SIZE ; try_blocksize *= 2) {
+ try_superblock = try_blocksize*8;
+ if (try_blocksize == 1024)
+ try_superblock++;
+ io_channel_set_blksize(io, try_blocksize);
+ if (io_channel_read_blk64(io, try_superblock,
+ -SUPERBLOCK_SIZE, buf))
+ continue;
+#ifdef WORDS_BIGENDIAN
+ 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) == try_blocksize)) {
+ ret_sb = try_superblock;
+ *superblock = try_superblock;
+ *block_size = try_blocksize;
+ break;
+ }
+ }
+
+cleanup:
+ if (io)
+ io_channel_close(io);
+ if (buf)
+ ext2fs_free_mem(&buf);
+ return ret_sb;
+}
+
+errcode_t ext2fs_try_backups(const char *name, const char *io_options,
+ int flags, blk64_t *superblock,
+ unsigned int *block_size, io_manager manager,
+ ext2_filsys *ret_fs)
+{
+ errcode_t retval;
+ blk64_t try_block_number;
+ unsigned int i;
+
+ /*
+ * Get first superblock location based on heuristic.
+ * Blocksize is also returned and used to find next
+ * superblock copy location.
+ */
+ try_block_number = ext2fs_first_backup_sb(superblock, block_size,
+ *ret_fs, name, manager);
+ retval = ext2fs_open2(name,
+ io_options, flags,
+ try_block_number, *block_size,
+ manager, ret_fs);
+ if (!retval)
+ return 0;
+
+ /*
+ * Trt 3d, 5th, 7th, 9th superblock copy
+ */
+ for (i = 3; i <= 9; i += 2) {
+ try_block_number = (i * (*block_size) * 8);
+ if (*block_size == 1024)
+ try_block_number++;
+ if (*ret_fs) {
+ ext2fs_free(*ret_fs);
+ *ret_fs = NULL;
+ }
+ retval = ext2fs_open2(name,
+ io_options, flags,
+ try_block_number, *block_size,
+ manager, ret_fs);
+ if (!retval) {
+ *superblock = try_block_number;
+ break;
+ }
+ }
+
+ return retval;
+}
+
errcode_t ext2fs_open2(const char *name, const char *io_options,
int flags, int superblock,
unsigned int block_size, io_manager manager,
diff --git a/misc/e2image.c b/misc/e2image.c
index b1b7a17d..069768e1 100644
--- a/misc/e2image.c
+++ b/misc/e2image.c
@@ -1611,8 +1611,14 @@ int main (int argc, char ** argv)
}
sprintf(offset_opt, "offset=%llu", source_offset);
retval = ext2fs_open2(device_name, offset_opt, open_flag,
- superblock, blocksize, unix_io_manager,
- &fs);
+ superblock, blocksize, unix_io_manager, &fs);
+ if (retval & (superblock | blocksize)) {
+ printf(_("Try backups in other location.\n"));
+ retval = ext2fs_try_backups(device_name, offset_opt, open_flag,
+ &superblock, &blocksize,
+ unix_io_manager, &fs);
+ printf(_("Use superblock %i.\n"), superblock);
+ }
if (retval) {
com_err (program_name, retval, _("while trying to open %s"),
device_name);
--
2.13.6 (Apple Git-96)
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