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Date: Mon, 11 Aug 2014 10:09:35 -0700
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: "Theodore Ts'o" <tytso@....edu>
Cc: Ext4 Developers List <linux-ext4@...r.kernel.org>,
Dan Jacobson <jidanni@...anni.org>
Subject: Re: [PATCH] e2fsck: flush out the superblock and bitmaps before
printing final messages
On Sun, Aug 10, 2014 at 05:33:44PM -0400, Theodore Ts'o wrote:
> A user who sees the message
>
> ***** REBOOT LINUX *****
>
> or
>
> ***** FILE SYSTEM WAS MODIFIED *****
>
> might think that e2fsck was complete even though we haven't finished
> writing out the superblock or bitmap blocks, and then either forcibly
> reboot or power cycle the box, or yank the USB key out while the
> storage device is still being written (before e2fsck exits).
>
> So rearrange the exit path of e2fsck so that we flush out the dirty
> superblock/bg descriptors/bitmaps before we print the final message.
> Also clean up this code so that the flow of control is easier to
> understand, and add error checking to catch any errors (normally
> caused by I/O errors writing to the disk) for these final writebacks.
Uh... if I run a readonly fsck, I see this:
# e2fsck -fn /tmp/a
e2fsck 1.43-WIP (09-Jul-2014)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Error writing block 2 (Attempt to write block to filesystem resulted in short write). Ignore error? no
Error writing block 2 (Attempt to write block to filesystem resulted in short write). Ignore error? no
Error writing file system info: Attempt to write block to filesystem resulted in short write
Looking at the strace output, it looks like a bunch of pwrite/write calls are
returning -EBADF when it tries to write the group descriptors to a O_RDONLY
file descriptor.
The call to ext2fs_flush() needs to be guarded by a "if (fs->flags &
EXT2_FLAG_DIRTY)" because ext2fs_flush() unconditionally writes out the group
descriptors. We don't want to do that unless the FS is actually dirty, and we
certainly don't want to do that for a RO check.
Will send patch shortly.
--D
>
> Addresses-Debian-Bugs: #757543, #757544
> Signed-off-by: Theodore Ts'o <tytso@....edu>
> Cc: Dan Jacobson <jidanni@...anni.org>
> ---
> e2fsck/problem.c | 15 ++++++++++++
> e2fsck/problem.h | 9 +++++++
> e2fsck/unix.c | 73 ++++++++++++++++++++++++++------------------------------
> 3 files changed, 58 insertions(+), 39 deletions(-)
>
> diff --git a/e2fsck/problem.c b/e2fsck/problem.c
> index 57c2e39..be4bd0c 100644
> --- a/e2fsck/problem.c
> +++ b/e2fsck/problem.c
> @@ -1737,6 +1737,21 @@ static struct e2fsck_problem problem_table[] = {
> N_("Update quota info for quota type %N"),
> PROMPT_NULL, PR_PREEN_OK },
>
> + /* Error setting block group checksum info */
> + { PR_6_SET_BG_CHECKSUM,
> + N_("Error setting @b @g checksum info: %m\n"),
> + PROMPT_NULL, PR_FATAL },
> +
> + /* Error writing file system info */
> + { PR_6_FLUSH_FILESYSTEM,
> + N_("Error writing file system info: %m\n"),
> + PROMPT_NULL, PR_FATAL },
> +
> + /* Error flushing writes to storage device */
> + { PR_6_IO_FLUSH,
> + N_("Error flushing writes to strage device: %m\n"),
> + PROMPT_NULL, PR_FATAL },
> +
> { 0 }
> };
>
> diff --git a/e2fsck/problem.h b/e2fsck/problem.h
> index 3426a22..212ed35 100644
> --- a/e2fsck/problem.h
> +++ b/e2fsck/problem.h
> @@ -1059,6 +1059,15 @@ struct problem_context {
> /* Update quota information if it is inconsistent */
> #define PR_6_UPDATE_QUOTAS 0x060002
>
> +/* Error setting block group checksum info */
> +#define PR_6_SET_BG_CHECKSUM 0x060003
> +
> +/* Error writing file system info */
> +#define PR_6_FLUSH_FILESYSTEM 0x060004
> +
> +/* Error flushing writes to storage device */
> +#define PR_6_IO_FLUSH 0x060005
> +
> /*
> * Function declarations
> */
> diff --git a/e2fsck/unix.c b/e2fsck/unix.c
> index fc05bde..628faeb 100644
> --- a/e2fsck/unix.c
> +++ b/e2fsck/unix.c
> @@ -1177,7 +1177,7 @@ int main (int argc, char *argv[])
> e2fsck_t ctx;
> blk64_t orig_superblock;
> struct problem_context pctx;
> - int flags, run_result;
> + int flags, run_result, was_changed;
> int journal_size;
> int sysval, sys_page_size = 4096;
> int old_bitmaps;
> @@ -1695,22 +1695,45 @@ no_journal:
> ext2fs_close_free(&fs);
> goto restart;
> }
> + if (run_result & E2F_FLAG_ABORT)
> + fatal_error(ctx, _("aborted"));
> +
> +#ifdef MTRACE
> + mtrace_print("Cleanup");
> +#endif
> + was_changed = ext2fs_test_changed(fs);
> if (run_result & E2F_FLAG_CANCEL) {
> log_out(ctx, _("%s: e2fsck canceled.\n"), ctx->device_name ?
> ctx->device_name : ctx->filesystem_name);
> exit_value |= FSCK_CANCELED;
> - }
> - if (run_result & E2F_FLAG_ABORT)
> - fatal_error(ctx, _("aborted"));
> - if (check_backup_super_block(ctx)) {
> - fs->flags &= ~EXT2_FLAG_MASTER_SB_ONLY;
> + } else if (!(ctx->options & E2F_OPT_READONLY)) {
> + if (ext2fs_test_valid(fs)) {
> + if (!(sb->s_state & EXT2_VALID_FS))
> + exit_value |= FSCK_NONDESTRUCT;
> + sb->s_state = EXT2_VALID_FS;
> + if (check_backup_super_block(ctx))
> + fs->flags &= ~EXT2_FLAG_MASTER_SB_ONLY;
> + } else
> + sb->s_state &= ~EXT2_VALID_FS;
> + if (!(ctx->flags & E2F_FLAG_TIME_INSANE))
> + sb->s_lastcheck = ctx->now;
> + sb->s_mnt_count = 0;
> + memset(((char *) sb) + EXT4_S_ERR_START, 0, EXT4_S_ERR_LEN);
> + pctx.errcode = ext2fs_set_gdt_csum(ctx->fs);
> + if (pctx.errcode)
> + fix_problem(ctx, PR_6_SET_BG_CHECKSUM, &pctx);
> ext2fs_mark_super_dirty(fs);
> }
>
> -#ifdef MTRACE
> - mtrace_print("Cleanup");
> -#endif
> - if (ext2fs_test_changed(fs)) {
> + e2fsck_write_bitmaps(ctx);
> + pctx.errcode = ext2fs_flush(ctx->fs);
> + if (pctx.errcode)
> + fix_problem(ctx, PR_6_FLUSH_FILESYSTEM, &pctx);
> + pctx.errcode = io_channel_flush(ctx->fs->io);
> + if (pctx.errcode)
> + fix_problem(ctx, PR_6_IO_FLUSH, &pctx);
> +
> + if (was_changed) {
> exit_value |= FSCK_NONDESTRUCT;
> if (!(ctx->options & E2F_OPT_PREEN))
> log_out(ctx, _("\n%s: ***** FILE SYSTEM WAS "
> @@ -1741,37 +1764,9 @@ no_journal:
> (sb->s_state & EXT2_VALID_FS) &&
> !(sb->s_state & EXT2_ERROR_FS))
> exit_value = 0;
> - } else {
> + } else
> show_stats(ctx);
> - if (!(ctx->options & E2F_OPT_READONLY)) {
> - if (ext2fs_test_valid(fs)) {
> - if (!(sb->s_state & EXT2_VALID_FS))
> - exit_value |= FSCK_NONDESTRUCT;
> - sb->s_state = EXT2_VALID_FS;
> - } else
> - sb->s_state &= ~EXT2_VALID_FS;
> - sb->s_mnt_count = 0;
> - if (!(ctx->flags & E2F_FLAG_TIME_INSANE))
> - sb->s_lastcheck = ctx->now;
> - memset(((char *) sb) + EXT4_S_ERR_START, 0,
> - EXT4_S_ERR_LEN);
> - ext2fs_mark_super_dirty(fs);
> - }
> - }
>
> - if ((run_result & E2F_FLAG_CANCEL) == 0 &&
> - sb->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM &&
> - !(ctx->options & E2F_OPT_READONLY)) {
> - retval = ext2fs_set_gdt_csum(ctx->fs);
> - if (retval) {
> - com_err(ctx->program_name, retval, "%s",
> - _("while setting block group checksum info"));
> - fatal_error(ctx, 0);
> - }
> - }
> -
> - e2fsck_write_bitmaps(ctx);
> - io_channel_flush(ctx->fs->io);
> print_resource_track(ctx, NULL, &ctx->global_rtrack, ctx->fs->io);
>
> ext2fs_close_free(&ctx->fs);
> --
> 2.0.0
>
> --
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