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Date: Wed, 1 Apr 2015 23:10:48 -0500
From: Andreas Dilger <adilger@...ger.ca>
To: "Darrick J. Wong" <darrick.wong@...cle.com>
Cc: "tytso@....edu" <tytso@....edu>,
"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 09/35] e2fsck: abort on read error beyond end of FS
It isn't clear what the benefit of this patch is? There are times (e.g. if
a partition table is broken or if a single-disk filesystem is changed
to an MD RAID device) that it is useful to run e2fsck on such a filesystem.
With this patch, it's essentially turning a small error into a fatal one, but
what is the benefit?
Cheers, Andreas
> On Apr 1, 2015, at 21:35, Darrick J. Wong <darrick.wong@...cle.com> wrote:
>
> Abort if we fail to read a block that's past the end of the FS.
> Includes a flag to disable the abort behavior for selected parts of
> the fsck run, so that we don't fail on a busted object prior to fixing
> it.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
> ---
> e2fsck/e2fsck.h | 1 +
> e2fsck/ehandler.c | 7 +++++--
> e2fsck/extents.c | 2 ++
> e2fsck/journal.c | 3 +++
> e2fsck/message.c | 12 +++++++++++-
> e2fsck/pass1.c | 28 ++++++++++++++++------------
> e2fsck/pass1b.c | 4 ++++
> 7 files changed, 42 insertions(+), 15 deletions(-)
>
>
> diff --git a/e2fsck/e2fsck.h b/e2fsck/e2fsck.h
> index 5fda863..453b552 100644
> --- a/e2fsck/e2fsck.h
> +++ b/e2fsck/e2fsck.h
> @@ -193,6 +193,7 @@ struct resource_track {
> #define E2F_FLAG_TIME_INSANE 0x2000 /* Time is insane */
> #define E2F_FLAG_PROBLEMS_FIXED 0x4000 /* At least one problem was fixed */
> #define E2F_FLAG_ALLOC_OK 0x8000 /* Can we allocate blocks? */
> +#define E2F_FLAG_IGNORE_READ_ERROR 0x10000 /* Don't rewrite read error blocks */
>
> #define E2F_RESET_FLAGS (E2F_FLAG_TIME_INSANE | E2F_FLAG_PROBLEMS_FIXED)
>
> diff --git a/e2fsck/ehandler.c b/e2fsck/ehandler.c
> index 71ca301..847f8e5 100644
> --- a/e2fsck/ehandler.c
> +++ b/e2fsck/ehandler.c
> @@ -60,8 +60,11 @@ static errcode_t e2fsck_handle_read_error(io_channel channel,
> preenhalt(ctx);
>
> /* Don't rewrite a block past the end of the FS. */
> - if (block >= ext2fs_blocks_count(fs->super))
> - return 0;
> + if (block >= ext2fs_blocks_count(fs->super)) {
> + if (ctx->flags & E2F_FLAG_IGNORE_READ_ERROR)
> + return 0;
> + abort();
> + }
>
> if (ask(ctx, _("Ignore error"), 1)) {
> if (ask(ctx, _("Force rewrite"), 1))
> diff --git a/e2fsck/extents.c b/e2fsck/extents.c
> index 8465299..cff265a 100644
> --- a/e2fsck/extents.c
> +++ b/e2fsck/extents.c
> @@ -29,6 +29,7 @@ errcode_t e2fsck_rebuild_extents_later(e2fsck_t ctx, ext2_ino_t ino)
> {
> if (!EXT2_HAS_INCOMPAT_FEATURE(ctx->fs->super,
> EXT3_FEATURE_INCOMPAT_EXTENTS) ||
> + (ctx->flags & (E2F_FLAG_RESTART_LATER | E2F_FLAG_RESTART)) ||
> (ctx->options & E2F_OPT_NO) ||
> (ino != EXT2_ROOT_INO && ino < ctx->fs->super->s_first_ino))
> return 0;
> @@ -339,6 +340,7 @@ static void rebuild_extents(e2fsck_t ctx, const char *pass_name, int pr_header)
>
> if (!EXT2_HAS_INCOMPAT_FEATURE(ctx->fs->super,
> EXT3_FEATURE_INCOMPAT_EXTENTS) ||
> + (ctx->flags & (E2F_FLAG_RESTART_LATER | E2F_FLAG_RESTART)) ||
> !ext2fs_test_valid(ctx->fs) ||
> ctx->invalid_bitmaps) {
> if (ctx->inodes_to_rebuild)
> diff --git a/e2fsck/journal.c b/e2fsck/journal.c
> index 9f32095..c195797 100644
> --- a/e2fsck/journal.c
> +++ b/e2fsck/journal.c
> @@ -315,6 +315,7 @@ static errcode_t e2fsck_get_journal(e2fsck_t ctx, journal_t **ret_journal)
> journal->j_inode = NULL;
> journal->j_blocksize = ctx->fs->blocksize;
>
> + ctx->flags |= E2F_FLAG_IGNORE_READ_ERROR;
> if (uuid_is_null(sb->s_journal_uuid)) {
> if (!sb->s_journal_inum) {
> retval = EXT2_ET_BAD_INODE_NUM;
> @@ -518,9 +519,11 @@ static errcode_t e2fsck_get_journal(e2fsck_t ctx, journal_t **ret_journal)
>
> *ret_journal = journal;
> e2fsck_use_inode_shortcuts(ctx, 0);
> + ctx->flags &= ~E2F_FLAG_IGNORE_READ_ERROR;
> return 0;
>
> errout:
> + ctx->flags &= ~E2F_FLAG_IGNORE_READ_ERROR;
> e2fsck_use_inode_shortcuts(ctx, 0);
> if (dev_fs)
> ext2fs_free_mem(&dev_fs);
> diff --git a/e2fsck/message.c b/e2fsck/message.c
> index 9c1433f..510f291 100644
> --- a/e2fsck/message.c
> +++ b/e2fsck/message.c
> @@ -199,14 +199,24 @@ static void print_pathname(FILE *f, ext2_filsys fs, ext2_ino_t dir,
> {
> errcode_t retval = 0;
> char *path;
> + e2fsck_t ctx = fs ? (e2fsck_t) fs->priv_data : NULL;
> + int flags;
>
> if (!dir && (ino < num_special_inodes)) {
> fputs(_(special_inode_name[ino]), f);
> return;
> }
>
> - if (fs)
> + if (fs) {
> + if (ctx) {
> + flags = ctx->flags;
> + ctx->flags |= E2F_FLAG_IGNORE_READ_ERROR;
> + }
> retval = ext2fs_get_pathname(fs, dir, ino, &path);
> + if (ctx)
> + ctx->flags &= ~E2F_FLAG_IGNORE_READ_ERROR |
> + (flags & E2F_FLAG_IGNORE_READ_ERROR);
> + }
> if (!fs || retval)
> fputs("???", f);
> else {
> diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
> index 308a95a..760fbde 100644
> --- a/e2fsck/pass1.c
> +++ b/e2fsck/pass1.c
> @@ -510,6 +510,7 @@ static void check_is_really_dir(e2fsck_t ctx, struct problem_context *pctx,
> int extent_fs;
> int inlinedata_fs;
>
> + ctx->flags |= E2F_FLAG_IGNORE_READ_ERROR;
> /*
> * If the mode looks OK, we believe it. If the first block in
> * the i_block array is 0, this cannot be a directory. If the
> @@ -519,7 +520,7 @@ static void check_is_really_dir(e2fsck_t ctx, struct problem_context *pctx,
> */
> if (LINUX_S_ISDIR(inode->i_mode) || LINUX_S_ISREG(inode->i_mode) ||
> LINUX_S_ISLNK(inode->i_mode) || inode->i_block[0] == 0)
> - return;
> + goto out;
>
> /*
> * Check the block numbers in the i_block array for validity:
> @@ -552,13 +553,13 @@ static void check_is_really_dir(e2fsck_t ctx, struct problem_context *pctx,
> struct ext2_dir_entry de;
>
> if (ext2fs_inline_data_size(ctx->fs, pctx->ino, &size))
> - return;
> + goto out;
> /*
> * If the size isn't a multiple of 4, it's probably not a
> * directory??
> */
> if (size & 3)
> - return;
> + goto out;
> /*
> * If the first 10 bytes don't look like a directory entry,
> * it's probably not a directory.
> @@ -578,14 +579,14 @@ static void check_is_really_dir(e2fsck_t ctx, struct problem_context *pctx,
> de.inode != 0) ||
> rec_len > EXT4_MIN_INLINE_DATA_SIZE -
> EXT4_INLINE_DATA_DOTDOT_SIZE)
> - return;
> + goto out;
> /* device files never have a "system.data" entry */
> goto isdir;
> } else if (extent_fs && (inode->i_flags & EXT4_EXTENTS_FL)) {
> /* extent mapped */
> if (ext2fs_bmap2(ctx->fs, pctx->ino, inode, 0, 0, 0, 0,
> &blk))
> - return;
> + goto out;
> /* device files are never extent mapped */
> not_device++;
> } else {
> @@ -600,7 +601,7 @@ static void check_is_really_dir(e2fsck_t ctx, struct problem_context *pctx,
> blk >= ext2fs_blocks_count(ctx->fs->super) ||
> ext2fs_fast_test_block_bitmap2(ctx->block_found_map,
> blk))
> - return; /* Invalid block, can't be dir */
> + goto out; /* Invalid block, can't be dir */
> }
> blk = inode->i_block[0];
> }
> @@ -612,45 +613,48 @@ static void check_is_really_dir(e2fsck_t ctx, struct problem_context *pctx,
> */
> if ((LINUX_S_ISCHR(inode->i_mode) || LINUX_S_ISBLK(inode->i_mode)) &&
> (inode->i_links_count == 1) && !not_device)
> - return;
> + goto out;
>
> /* read the first block */
> ehandler_operation(_("reading directory block"));
> retval = ext2fs_read_dir_block4(ctx->fs, blk, buf, 0, pctx->ino);
> ehandler_operation(0);
> if (retval)
> - return;
> + goto out;
>
> dirent = (struct ext2_dir_entry *) buf;
> retval = ext2fs_get_rec_len(ctx->fs, dirent, &rec_len);
> if (retval)
> - return;
> + goto out;
> if ((ext2fs_dirent_name_len(dirent) != 1) ||
> (dirent->name[0] != '.') ||
> (dirent->inode != pctx->ino) ||
> (rec_len < 12) ||
> (rec_len % 4) ||
> (rec_len >= ctx->fs->blocksize - 12))
> - return;
> + goto out;
>
> dirent = (struct ext2_dir_entry *) (buf + rec_len);
> retval = ext2fs_get_rec_len(ctx->fs, dirent, &rec_len);
> if (retval)
> - return;
> + goto out;
> if ((ext2fs_dirent_name_len(dirent) != 2) ||
> (dirent->name[0] != '.') ||
> (dirent->name[1] != '.') ||
> (rec_len < 12) ||
> (rec_len % 4))
> - return;
> + goto out;
>
> isdir:
> + ctx->flags &= ~E2F_FLAG_IGNORE_READ_ERROR;
> if (fix_problem(ctx, PR_1_TREAT_AS_DIRECTORY, pctx)) {
> inode->i_mode = (inode->i_mode & 07777) | LINUX_S_IFDIR;
> e2fsck_write_inode_full(ctx, pctx->ino, inode,
> EXT2_INODE_SIZE(ctx->fs->super),
> "check_is_really_dir");
> }
> +out:
> + ctx->flags &= ~E2F_FLAG_IGNORE_READ_ERROR;
> }
>
> void e2fsck_setup_tdb_icount(e2fsck_t ctx, int flags,
> diff --git a/e2fsck/pass1b.c b/e2fsck/pass1b.c
> index cd967f4..10136a6 100644
> --- a/e2fsck/pass1b.c
> +++ b/e2fsck/pass1b.c
> @@ -234,7 +234,9 @@ void e2fsck_pass1_dupblocks(e2fsck_t ctx, char *block_buf)
> dict_set_allocator(&clstr_dict, NULL, cluster_dnode_free, NULL);
>
> init_resource_track(&rtrack, ctx->fs->io);
> + ctx->flags |= E2F_FLAG_IGNORE_READ_ERROR;
> pass1b(ctx, block_buf);
> + ctx->flags &= ~E2F_FLAG_IGNORE_READ_ERROR;
> print_resource_track(ctx, "Pass 1b", &rtrack, ctx->fs->io);
>
> init_resource_track(&rtrack, ctx->fs->io);
> @@ -242,7 +244,9 @@ void e2fsck_pass1_dupblocks(e2fsck_t ctx, char *block_buf)
> print_resource_track(ctx, "Pass 1c", &rtrack, ctx->fs->io);
>
> init_resource_track(&rtrack, ctx->fs->io);
> + ctx->flags |= E2F_FLAG_IGNORE_READ_ERROR;
> pass1d(ctx, block_buf);
> + ctx->flags &= ~E2F_FLAG_IGNORE_READ_ERROR;
> print_resource_track(ctx, "Pass 1d", &rtrack, ctx->fs->io);
>
> /*
>
> --
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