| Message ID | 500F1C28.8010800@redhat.com |
|---|---|
| State | Accepted, archived |
| Headers | show |
On 7/24/12 5:05 PM, Eric Sandeen wrote: > This sequence: > > # truncate --size=65536 fsfile > # losetup --offset 65536 /dev/loop0 fsfile > # mkfs.ext4 /dev/loop0 > # losetup -d /dev/loop0 > # mount -o loop,ro,offset=65536 fsfile mnt/ > # umount mnt > # dmesg | tail > > results in an IO error when unmounting the RO filesystem: > > [ 312.386074] SELinux: initialized (dev loop1, type ext4), uses xattr > [ 318.020828] Buffer I/O error on device loop1, logical block 196608 > [ 318.027024] lost page write due to I/O error on loop1 > [ 318.032088] JBD2: Error -5 detected when updating journal superblock for loop1-8. > > This behavior changed with: > > commit 24bcc89c7e7c64982e6192b4952a0a92379fc341 > Author: Jan Kara <jack@suse.cz> > Date: Tue Mar 13 15:41:04 2012 -0400 > > jbd2: split updating of journal superblock and marking journal empty > > which lost some of the magic in jbd2_journal_update_superblock() which > used to test for a journal with no outstanding transactions. > > I'm not sure if the following is quite the right approach, but it fixes > it for me. > > Signed-off-by: Eric Sandeen <sandeen@redhat.com> > --- > > p.s. no idea why this only happens if I use a loop device with an offset! PEBKAC. no-offset ro loop mount does the same. -Eric -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 24 Jul 2012, Eric Sandeen wrote: > Date: Tue, 24 Jul 2012 17:05:28 -0500 > From: Eric Sandeen <sandeen@redhat.com> > To: ext4 development <linux-ext4@vger.kernel.org> > Cc: Jan Kara <jack@suse.cz> > Subject: [PATCH] jbd2: don't write superblock when unmounting an ro filesystem > > This sequence: > > # truncate --size=65536 fsfile > # losetup --offset 65536 /dev/loop0 fsfile > # mkfs.ext4 /dev/loop0 > # losetup -d /dev/loop0 > # mount -o loop,ro,offset=65536 fsfile mnt/ > # umount mnt > # dmesg | tail Hi Eric, I am having hard time understanding what the sequence should be doing. I actually can not reproduce it, because I can not create the file system on such loop device because it seems like the size of /dev/loop0 is zero, which makes sense considering that you set offset to 65536 in the 65536 sized file. Also, is the use of lo device really needed ? We can create the file system on the file itself right ? Moreover, when I do that I can see that the journal is not created because the device (file) is too small, maybe it have something to do with the problem ? Anyway, maybe I am missing something, but I do not understand what kind of problem are you reproducing there. -Lukas > > results in an IO error when unmounting the RO filesystem: > > [ 312.386074] SELinux: initialized (dev loop1, type ext4), uses xattr > [ 318.020828] Buffer I/O error on device loop1, logical block 196608 > [ 318.027024] lost page write due to I/O error on loop1 > [ 318.032088] JBD2: Error -5 detected when updating journal superblock for loop1-8. > > This behavior changed with: > > commit 24bcc89c7e7c64982e6192b4952a0a92379fc341 > Author: Jan Kara <jack@suse.cz> > Date: Tue Mar 13 15:41:04 2012 -0400 > > jbd2: split updating of journal superblock and marking journal empty > > which lost some of the magic in jbd2_journal_update_superblock() which > used to test for a journal with no outstanding transactions. > > I'm not sure if the following is quite the right approach, but it fixes > it for me. > > Signed-off-by: Eric Sandeen <sandeen@redhat.com> > --- > > p.s. no idea why this only happens if I use a loop device with an offset! > > diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c > index e9a3c4c..987ec76 100644 > --- a/fs/jbd2/journal.c > +++ b/fs/jbd2/journal.c > @@ -1354,6 +1354,11 @@ static void jbd2_mark_journal_empty(journal_t *journal) > > BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex)); > read_lock(&journal->j_state_lock); > + /* Is it already empty? */ > + if (sb->s_start == 0) { > + read_unlock(&journal->j_state_lock); > + return; > + } > jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n", > journal->j_tail_sequence); > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 7/26/12 4:24 AM, Lukáš Czerner wrote: > On Tue, 24 Jul 2012, Eric Sandeen wrote: > >> Date: Tue, 24 Jul 2012 17:05:28 -0500 >> From: Eric Sandeen <sandeen@redhat.com> >> To: ext4 development <linux-ext4@vger.kernel.org> >> Cc: Jan Kara <jack@suse.cz> >> Subject: [PATCH] jbd2: don't write superblock when unmounting an ro filesystem >> >> This sequence: >> >> # truncate --size=65536 fsfile >> # losetup --offset 65536 /dev/loop0 fsfile >> # mkfs.ext4 /dev/loop0 >> # losetup -d /dev/loop0 >> # mount -o loop,ro,offset=65536 fsfile mnt/ >> # umount mnt >> # dmesg | tail > > Hi Eric, > > I am having hard time understanding what the sequence should be > doing. I actually can not reproduce it, because I can not create the > file system on such loop device because it seems like the size of > /dev/loop0 is zero, which makes sense considering that you set > offset to 65536 in the 65536 sized file. sorry, that must have been a cut & paste error. :( The offset was leftover from trying to match the original reporter's case. This simpler test shows the same problem: 1014 truncate --size=2g fsfile 1015 mkfs.ext4 fsfile 1016 mount -o loop,ro fsfile mnt 1017 umount mnt 1018 dmesg | tail [ 417.631105] EXT4-fs (loop0): mounted filesystem with ordered data mode. Opts: (null) [ 417.639183] SELinux: initialized (dev loop0, type ext4), uses xattr [ 420.903970] Buffer I/O error on device loop0, logical block 262144 [ 420.910448] lost page write due to I/O error on loop0 [ 420.915662] JBD2: Error -5 detected when updating journal superblock for loop0-8. > Also, is the use of lo device really needed ? We can create the file > system on the file itself right ? Moreover, when I do that I can see > that the journal is not created because the device (file) is too > small, maybe it have something to do with the problem ? > > Anyway, maybe I am missing something, but I do not understand what > kind of problem are you reproducing there. > > -Lukas > >> >> results in an IO error when unmounting the RO filesystem: >> >> [ 312.386074] SELinux: initialized (dev loop1, type ext4), uses xattr >> [ 318.020828] Buffer I/O error on device loop1, logical block 196608 >> [ 318.027024] lost page write due to I/O error on loop1 >> [ 318.032088] JBD2: Error -5 detected when updating journal superblock for loop1-8. >> >> This behavior changed with: >> >> commit 24bcc89c7e7c64982e6192b4952a0a92379fc341 >> Author: Jan Kara <jack@suse.cz> >> Date: Tue Mar 13 15:41:04 2012 -0400 >> >> jbd2: split updating of journal superblock and marking journal empty >> >> which lost some of the magic in jbd2_journal_update_superblock() which >> used to test for a journal with no outstanding transactions. >> >> I'm not sure if the following is quite the right approach, but it fixes >> it for me. >> >> Signed-off-by: Eric Sandeen <sandeen@redhat.com> >> --- >> >> p.s. no idea why this only happens if I use a loop device with an offset! >> >> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c >> index e9a3c4c..987ec76 100644 >> --- a/fs/jbd2/journal.c >> +++ b/fs/jbd2/journal.c >> @@ -1354,6 +1354,11 @@ static void jbd2_mark_journal_empty(journal_t *journal) >> >> BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex)); >> read_lock(&journal->j_state_lock); >> + /* Is it already empty? */ >> + if (sb->s_start == 0) { >> + read_unlock(&journal->j_state_lock); >> + return; >> + } >> jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n", >> journal->j_tail_sequence); >> >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue 24-07-12 17:05:28, Eric Sandeen wrote: > This sequence: > > # truncate --size=65536 fsfile > # losetup --offset 65536 /dev/loop0 fsfile > # mkfs.ext4 /dev/loop0 > # losetup -d /dev/loop0 > # mount -o loop,ro,offset=65536 fsfile mnt/ > # umount mnt > # dmesg | tail > > results in an IO error when unmounting the RO filesystem: > > [ 312.386074] SELinux: initialized (dev loop1, type ext4), uses xattr > [ 318.020828] Buffer I/O error on device loop1, logical block 196608 > [ 318.027024] lost page write due to I/O error on loop1 > [ 318.032088] JBD2: Error -5 detected when updating journal superblock for loop1-8. Ted, did this patch fall through cracks? I've ported the fix to JBD and added it to my tree. I plan to send it to Linus in a few days. Also I've CC'd stable since this is a bit annoying regression. Honza > This behavior changed with: > > commit 24bcc89c7e7c64982e6192b4952a0a92379fc341 > Author: Jan Kara <jack@suse.cz> > Date: Tue Mar 13 15:41:04 2012 -0400 > > jbd2: split updating of journal superblock and marking journal empty > > which lost some of the magic in jbd2_journal_update_superblock() which > used to test for a journal with no outstanding transactions. > > I'm not sure if the following is quite the right approach, but it fixes > it for me. > > Signed-off-by: Eric Sandeen <sandeen@redhat.com> > --- > > p.s. no idea why this only happens if I use a loop device with an offset! > > diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c > index e9a3c4c..987ec76 100644 > --- a/fs/jbd2/journal.c > +++ b/fs/jbd2/journal.c > @@ -1354,6 +1354,11 @@ static void jbd2_mark_journal_empty(journal_t *journal) > > BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex)); > read_lock(&journal->j_state_lock); > + /* Is it already empty? */ > + if (sb->s_start == 0) { > + read_unlock(&journal->j_state_lock); > + return; > + } > jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n", > journal->j_tail_sequence); > >
On 8/15/12 7:14 AM, Jan Kara wrote: > On Tue 24-07-12 17:05:28, Eric Sandeen wrote: >> This sequence: >> >> # truncate --size=65536 fsfile >> # losetup --offset 65536 /dev/loop0 fsfile >> # mkfs.ext4 /dev/loop0 >> # losetup -d /dev/loop0 >> # mount -o loop,ro,offset=65536 fsfile mnt/ >> # umount mnt >> # dmesg | tail >> >> results in an IO error when unmounting the RO filesystem: >> >> [ 312.386074] SELinux: initialized (dev loop1, type ext4), uses xattr >> [ 318.020828] Buffer I/O error on device loop1, logical block 196608 >> [ 318.027024] lost page write due to I/O error on loop1 >> [ 318.032088] JBD2: Error -5 detected when updating journal superblock for loop1-8. > Ted, did this patch fall through cracks? I've ported the fix to JBD and > added it to my tree. I plan to send it to Linus in a few days. Also I've > CC'd stable since this is a bit annoying regression. > > Honza Thanks for doing both of those things, Jan. BTW this happens on loop because mount -o,ro apparently sets up the loop device itself as readonly. -Eric -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Applied, thanks. I updated the reproduction instructions so that they wored correctly. (i.e., by removing the offset, and changing the size to 1g). - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Aug 18, 2012, at 11:45 AM, "Theodore Ts'o" <tytso@mit.edu> wrote: > Applied, thanks. I updated the reproduction instructions so that they > wored correctly. (i.e., by removing the offset, and changing the size > to 1g). > Thanks, sorry about that really messed up commit message. :( -Eric > - Ted > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index e9a3c4c..987ec76 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1354,6 +1354,11 @@ static void jbd2_mark_journal_empty(journal_t *journal) BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex)); read_lock(&journal->j_state_lock); + /* Is it already empty? */ + if (sb->s_start == 0) { + read_unlock(&journal->j_state_lock); + return; + } jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n", journal->j_tail_sequence);
This sequence: # truncate --size=65536 fsfile # losetup --offset 65536 /dev/loop0 fsfile # mkfs.ext4 /dev/loop0 # losetup -d /dev/loop0 # mount -o loop,ro,offset=65536 fsfile mnt/ # umount mnt # dmesg | tail results in an IO error when unmounting the RO filesystem: [ 312.386074] SELinux: initialized (dev loop1, type ext4), uses xattr [ 318.020828] Buffer I/O error on device loop1, logical block 196608 [ 318.027024] lost page write due to I/O error on loop1 [ 318.032088] JBD2: Error -5 detected when updating journal superblock for loop1-8. This behavior changed with: commit 24bcc89c7e7c64982e6192b4952a0a92379fc341 Author: Jan Kara <jack@suse.cz> Date: Tue Mar 13 15:41:04 2012 -0400 jbd2: split updating of journal superblock and marking journal empty which lost some of the magic in jbd2_journal_update_superblock() which used to test for a journal with no outstanding transactions. I'm not sure if the following is quite the right approach, but it fixes it for me. Signed-off-by: Eric Sandeen <sandeen@redhat.com> --- p.s. no idea why this only happens if I use a loop device with an offset! -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html