diff mbox series

[RFC,v2,1/5] jbd2: test case for ext4 data=journal/mmap() journal corruption

Message ID 20200810010210.3305322-2-mfo@canonical.com
State Superseded
Headers show
Series ext4/jbd2: data=journal: write-protect pages on transaction commit | expand

Commit Message

Mauricio Faria de Oliveira Aug. 10, 2020, 1:02 a.m. UTC 
This checks during journal commit, right after calculating the
checksum of a buffer head, whether its contents match the 'BUG'
string (the cookie string in the test case userspace part.)

If so, it sleeps 5 seconds for such contents to change (i.e.,
so that the actual checksum changes from what was calculated.)

And if it changed, set a flag to panic after committing to disk.

Then, on filesystem remount/journal recovery there is an invalid
checksum error, and recovery fails:

  $ sudo mount -o data=journal,journal_checksum $DEV $MNT
  [ 100.832223] EXT4-fs: Warning: mounting with data=journal disables
  delayed allocation, dioread_nolock, and O_DIRECT support!
  [ 100.837488] JBD2: Invalid checksum recovering data block 8706 in log
  [ 100.842010] JBD2: recovery failed
  [ 100.843045] EXT4-fs (loop0): error loading journal
  mount: /ext4: can't read superblock on /dev/loop0.
---
 fs/jbd2/commit.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

Comments

Jan Kara Aug. 18, 2020, 2:38 p.m. UTC | #1 
On Sun 09-08-20 22:02:04, Mauricio Faria de Oliveira wrote:
> This checks during journal commit, right after calculating the
> checksum of a buffer head, whether its contents match the 'BUG'
> string (the cookie string in the test case userspace part.)
> 
> If so, it sleeps 5 seconds for such contents to change (i.e.,
> so that the actual checksum changes from what was calculated.)
> 
> And if it changed, set a flag to panic after committing to disk.
> 
> Then, on filesystem remount/journal recovery there is an invalid
> checksum error, and recovery fails:
> 
>   $ sudo mount -o data=journal,journal_checksum $DEV $MNT
>   [ 100.832223] EXT4-fs: Warning: mounting with data=journal disables
>   delayed allocation, dioread_nolock, and O_DIRECT support!
>   [ 100.837488] JBD2: Invalid checksum recovering data block 8706 in log
>   [ 100.842010] JBD2: recovery failed
>   [ 100.843045] EXT4-fs (loop0): error loading journal
>   mount: /ext4: can't read superblock on /dev/loop0.

Nice to have this for testing but when you'll do some "official"
submission, just send this patch separately so that it's clear shouldn't be
included in the kernel...

								Honza

> ---
>  fs/jbd2/commit.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
> index 6d2da8ad0e6f..51f713089e35 100644
> --- a/fs/jbd2/commit.c
> +++ b/fs/jbd2/commit.c
> @@ -26,6 +26,11 @@
>  #include <linux/bitops.h>
>  #include <trace/events/jbd2.h>
>  
> +#include <linux/printk.h>
> +#include <linux/delay.h>
> +
> +static journal_t *force_panic;
> +
>  /*
>   * IO end handler for temporary buffer_heads handling writes to the journal.
>   */
> @@ -331,14 +336,35 @@ static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
>  	__u32 csum32;
>  	__be32 seq;
>  
> +	// For the testcase
> +	__u32 csum32_later;
> +	__u8 *bh_data;
> +
>  	if (!jbd2_journal_has_csum_v2or3(j))
>  		return;
>  
>  	seq = cpu_to_be32(sequence);
>  	addr = kmap_atomic(page);
>  	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
> +	csum32_later = csum32; // Copy csum32 to check again later
>  	csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),
>  			     bh->b_size);
> +
> +	// Check for testcase cookie 'BUG' in the buffer_head data.
> +	bh_data = addr + offset_in_page(bh->b_data);
> +	if (bh_data[0] == 'B' &&
> +	    bh_data[1] == 'U' &&
> +	    bh_data[2] == 'G') {
> +		pr_info("TESTCASE: Cookie found. Waiting 5 seconds for changes.\n");
> +		msleep(5000);
> +		pr_info("TESTCASE: Cookie eaten. Resumed.\n");
> +	}
> +
> +	// Check the checksum again for changes/panic after commit.
> +	csum32_later = jbd2_chksum(j, csum32_later, addr + offset_in_page(bh->b_data), bh->b_size);
> +	if (csum32 != csum32_later)
> +		force_panic = j;
> +
>  	kunmap_atomic(addr);
>  
>  	if (jbd2_has_feature_csum3(j))
> @@ -885,6 +911,9 @@ void jbd2_journal_commit_transaction(journal_t *journal)
>  		blkdev_issue_flush(journal->j_dev, GFP_NOFS);
>  	}
>  
> +	if (force_panic == journal)
> +		panic("TESTCASE: checksum changed; commit record done; panic!\n");
> +
>  	if (err)
>  		jbd2_journal_abort(journal, err);
>  
> -- 
> 2.17.1
>
Mauricio Faria de Oliveira Aug. 19, 2020, 1:15 a.m. UTC | #2 
On Tue, Aug 18, 2020 at 11:38 AM Jan Kara <jack@suse.cz> wrote:
>
> On Sun 09-08-20 22:02:04, Mauricio Faria de Oliveira wrote:
> > This checks during journal commit, right after calculating the
> > checksum of a buffer head, whether its contents match the 'BUG'
> > string (the cookie string in the test case userspace part.)
> >
> > If so, it sleeps 5 seconds for such contents to change (i.e.,
> > so that the actual checksum changes from what was calculated.)
> >
> > And if it changed, set a flag to panic after committing to disk.
> >
> > Then, on filesystem remount/journal recovery there is an invalid
> > checksum error, and recovery fails:
> >
> >   $ sudo mount -o data=journal,journal_checksum $DEV $MNT
> >   [ 100.832223] EXT4-fs: Warning: mounting with data=journal disables
> >   delayed allocation, dioread_nolock, and O_DIRECT support!
> >   [ 100.837488] JBD2: Invalid checksum recovering data block 8706 in log
> >   [ 100.842010] JBD2: recovery failed
> >   [ 100.843045] EXT4-fs (loop0): error loading journal
> >   mount: /ext4: can't read superblock on /dev/loop0.
>
> Nice to have this for testing but when you'll do some "official"
> submission, just send this patch separately so that it's clear shouldn't be
> included in the kernel...
>

Yup, absolutely. :) I forgot to make its subject line different as in
other test-case parts.

>                                                                 Honza
>
> > ---
> >  fs/jbd2/commit.c | 29 +++++++++++++++++++++++++++++
> >  1 file changed, 29 insertions(+)
> >
> > diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
> > index 6d2da8ad0e6f..51f713089e35 100644
> > --- a/fs/jbd2/commit.c
> > +++ b/fs/jbd2/commit.c
> > @@ -26,6 +26,11 @@
> >  #include <linux/bitops.h>
> >  #include <trace/events/jbd2.h>
> >
> > +#include <linux/printk.h>
> > +#include <linux/delay.h>
> > +
> > +static journal_t *force_panic;
> > +
> >  /*
> >   * IO end handler for temporary buffer_heads handling writes to the journal.
> >   */
> > @@ -331,14 +336,35 @@ static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
> >       __u32 csum32;
> >       __be32 seq;
> >
> > +     // For the testcase
> > +     __u32 csum32_later;
> > +     __u8 *bh_data;
> > +
> >       if (!jbd2_journal_has_csum_v2or3(j))
> >               return;
> >
> >       seq = cpu_to_be32(sequence);
> >       addr = kmap_atomic(page);
> >       csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
> > +     csum32_later = csum32; // Copy csum32 to check again later
> >       csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),
> >                            bh->b_size);
> > +
> > +     // Check for testcase cookie 'BUG' in the buffer_head data.
> > +     bh_data = addr + offset_in_page(bh->b_data);
> > +     if (bh_data[0] == 'B' &&
> > +         bh_data[1] == 'U' &&
> > +         bh_data[2] == 'G') {
> > +             pr_info("TESTCASE: Cookie found. Waiting 5 seconds for changes.\n");
> > +             msleep(5000);
> > +             pr_info("TESTCASE: Cookie eaten. Resumed.\n");
> > +     }
> > +
> > +     // Check the checksum again for changes/panic after commit.
> > +     csum32_later = jbd2_chksum(j, csum32_later, addr + offset_in_page(bh->b_data), bh->b_size);
> > +     if (csum32 != csum32_later)
> > +             force_panic = j;
> > +
> >       kunmap_atomic(addr);
> >
> >       if (jbd2_has_feature_csum3(j))
> > @@ -885,6 +911,9 @@ void jbd2_journal_commit_transaction(journal_t *journal)
> >               blkdev_issue_flush(journal->j_dev, GFP_NOFS);
> >       }
> >
> > +     if (force_panic == journal)
> > +             panic("TESTCASE: checksum changed; commit record done; panic!\n");
> > +
> >       if (err)
> >               jbd2_journal_abort(journal, err);
> >
> > --
> > 2.17.1
> >
> --
> Jan Kara <jack@suse.com>
> SUSE Labs, CR
diff mbox series

Patch

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 6d2da8ad0e6f..51f713089e35 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -26,6 +26,11 @@ 
 #include <linux/bitops.h>
 #include <trace/events/jbd2.h>
 
+#include <linux/printk.h>
+#include <linux/delay.h>
+
+static journal_t *force_panic;
+
 /*
  * IO end handler for temporary buffer_heads handling writes to the journal.
  */
@@ -331,14 +336,35 @@  static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
 	__u32 csum32;
 	__be32 seq;
 
+	// For the testcase
+	__u32 csum32_later;
+	__u8 *bh_data;
+
 	if (!jbd2_journal_has_csum_v2or3(j))
 		return;
 
 	seq = cpu_to_be32(sequence);
 	addr = kmap_atomic(page);
 	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
+	csum32_later = csum32; // Copy csum32 to check again later
 	csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),
 			     bh->b_size);
+
+	// Check for testcase cookie 'BUG' in the buffer_head data.
+	bh_data = addr + offset_in_page(bh->b_data);
+	if (bh_data[0] == 'B' &&
+	    bh_data[1] == 'U' &&
+	    bh_data[2] == 'G') {
+		pr_info("TESTCASE: Cookie found. Waiting 5 seconds for changes.\n");
+		msleep(5000);
+		pr_info("TESTCASE: Cookie eaten. Resumed.\n");
+	}
+
+	// Check the checksum again for changes/panic after commit.
+	csum32_later = jbd2_chksum(j, csum32_later, addr + offset_in_page(bh->b_data), bh->b_size);
+	if (csum32 != csum32_later)
+		force_panic = j;
+
 	kunmap_atomic(addr);
 
 	if (jbd2_has_feature_csum3(j))
@@ -885,6 +911,9 @@  void jbd2_journal_commit_transaction(journal_t *journal)
 		blkdev_issue_flush(journal->j_dev, GFP_NOFS);
 	}
 
+	if (force_panic == journal)
+		panic("TESTCASE: checksum changed; commit record done; panic!\n");
+
 	if (err)
 		jbd2_journal_abort(journal, err);