| Message ID | m2uac8f92701004042130o76a81f3az89d538ebe0afea31@mail.gmail.com |
|---|---|
| State | New, archived |
| Headers | show |
jing zhang wrote: > From: Jing Zhang <zj.barak@gmail.com> > > Date: Mon Apr 5 12:10:50 2010 > > BUG_ON is triggered at [line:1762] in ext4_mb_complex_scan_group(), Do you have a test case which can trigger this BUG_ON? -Eric > and fix is to change the return value of mb_find_extent() if the > needed extent can not be found. The fix can also be applied to other > points where mb_find_extent() is called. > > Cc: Theodore Ts'o <tytso@mit.edu> > Cc: Andreas Dilger <adilger@sun.com> > Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com> > Cc: "Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com> > Signed-off-by: Jing Zhang <zj.barak@gmail.com> > --- > fs/ext4/mballoc.c | 7 +++++-- > 1 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > index bba1282..fbb6899 100644 > --- a/fs/ext4/mballoc.c > +++ b/fs/ext4/mballoc.c > @@ -1321,7 +1321,7 @@ static int mb_find_extent(struct ext4_buddy > *e4b, int order, int block, > ex->fe_len = 0; > ex->fe_start = 0; > ex->fe_group = 0; > - return 0; > + return -ENOSPC; > } > > /* FIXME dorp order completely ? */ > @@ -1358,6 +1358,8 @@ static int mb_find_extent(struct ext4_buddy > *e4b, int order, int block, > } > > BUG_ON(ex->fe_start + ex->fe_len > (1 << (e4b->bd_blkbits + 3))); > + if (needed > ex->fe_len) > + return -ENOSPC; > return ex->fe_len; > } > > @@ -1758,7 +1760,8 @@ void ext4_mb_complex_scan_group(struct > ext4_allocation_context *ac, > break; > } > > - mb_find_extent(e4b, 0, i, ac->ac_g_ex.fe_len, &ex); > + if (0 > mb_find_extent(e4b, 0, i, ac->ac_g_ex.fe_len, &ex)) > + break; > BUG_ON(ex.fe_len <= 0); > if (free < ex.fe_len) { > ext4_grp_locked_error(sb, e4b->bd_group, > -- > 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
2010/4/5, Eric Sandeen <sandeen@redhat.com>: > jing zhang wrote: >> From: Jing Zhang <zj.barak@gmail.com> >> >> Date: Mon Apr 5 12:10:50 2010 >> >> BUG_ON is triggered at [line:1762] in ext4_mb_complex_scan_group(), > > Do you have a test case which can trigger this BUG_ON? > > -Eric No I do not have. But you can check [line: 1762] and [line: 1321]. And please info me the result, if you like, after check. - zj -- 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 Mon, Apr 05, 2010 at 01:01:31PM +0800, jing zhang wrote: > 2010/4/5, Eric Sandeen <sandeen@redhat.com>: > > jing zhang wrote: > >> From: Jing Zhang <zj.barak@gmail.com> > >> > >> Date: Mon Apr 5 12:10:50 2010 > >> > >> BUG_ON is triggered at [line:1762] in ext4_mb_complex_scan_group(), > > > > Do you have a test case which can trigger this BUG_ON? > > > > -Eric > > No I do not have. > > But you can check [line: 1762] and [line: 1321]. > > And please info me the result, if you like, after check. Again, line numbers make it hard to determine what you're talking about. And we need a scenario description that might trigger this. If you can't give it, then my fear is that you don't understand how the code is used, in which case the risk is extremely high that that your patch will not be correct, and may in fact may make things worse. I could spend time trying to reverse engineer the scenario where this might happen, but the fact of the matter is, no one has reported these BUG_ON's ever triggering as far as I know. So when I have free time, I might get back to looking for them. Otherwise, I have higher priority things to work on, and it's going to be up to you to pursuade me that this could actually happen in real life, and how. Best regards, - 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
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index bba1282..fbb6899 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1321,7 +1321,7 @@ static int mb_find_extent(struct ext4_buddy *e4b, int order, int block, ex->fe_len = 0; ex->fe_start = 0; ex->fe_group = 0; - return 0; + return -ENOSPC; }