From: Artem Blagodarenko Subject: [PATCH v3 4/4] ext2fs: automaticlly open backup superblocks Date: Mon, 4 Dec 2017 22:35:30 +0300 Message-ID: <20171204193530.54888-5-artem.blagodarenko@gmail.com> References: <20171204193530.54888-1-artem.blagodarenko@gmail.com> Cc: adilger.kernel@dilger.ca To: linux-ext4@vger.kernel.org Return-path: Received: from mail-lf0-f67.google.com ([209.85.215.67]:46033 "EHLO mail-lf0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751104AbdLDTfq (ORCPT ); Mon, 4 Dec 2017 14:35:46 -0500 Received: by mail-lf0-f67.google.com with SMTP id f13so20450834lff.12 for ; Mon, 04 Dec 2017 11:35:45 -0800 (PST) In-Reply-To: <20171204193530.54888-1-artem.blagodarenko@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: 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 --- 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)