| Message ID | 4C7D0FAB.9070501@redhat.com |
|---|---|
| State | Accepted, archived |
| Headers | show |
Eric Sandeen wrote: > In some cases we can reach ext4_da_writepages() with > wbc->nr_to_write == LONG_MAX, !range_cyclic, and range_whole=1; > in this case we will try to bump it up by a factor of 8, which > leads to a desired_nr_to_write value of -8. Sorry Ted, hold off on this, it should have been LLONG_MAX of course, and I'm still looking for one other bit of brokennes I see. The 1/2 patch should be good though. -Eric > We still get through the logic without actually changing > wbc->nr_to_write because the other tests which would change > it don't trip due to the negative value, but it seems dangerous > to overflow desired_nr_to_write in the interim, it's not an > obvious situation. > > Signed-off-by: Eric Sandeen <sandeen@redhat.com> > --- > > (V2 minor commit message edits) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 93497f6..2e72a4a 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3004,9 +3004,11 @@ static int ext4_da_writepages(struct address_space *mapping, > * sbi->max_writeback_mb_bump whichever is smaller. > */ > max_pages = sbi->s_max_writeback_mb_bump << (20 - PAGE_CACHE_SHIFT); > - if (!range_cyclic && range_whole) > - desired_nr_to_write = wbc->nr_to_write * 8; > - else > + if (!range_cyclic && range_whole) { > + desired_nr_to_write = wbc->nr_to_write; > + if (desired_nr_to_write != LONG_MAX) > + desired_nr_to_write *= 8; > + } else > desired_nr_to_write = ext4_num_dirty_pages(inode, index, > max_pages); > if (desired_nr_to_write > max_pages) > > > -- > 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 -- 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/inode.c b/fs/ext4/inode.c index 93497f6..2e72a4a 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3004,9 +3004,11 @@ static int ext4_da_writepages(struct address_space *mapping, * sbi->max_writeback_mb_bump whichever is smaller. */ max_pages = sbi->s_max_writeback_mb_bump << (20 - PAGE_CACHE_SHIFT); - if (!range_cyclic && range_whole) - desired_nr_to_write = wbc->nr_to_write * 8; - else + if (!range_cyclic && range_whole) { + desired_nr_to_write = wbc->nr_to_write; + if (desired_nr_to_write != LONG_MAX) + desired_nr_to_write *= 8; + } else desired_nr_to_write = ext4_num_dirty_pages(inode, index, max_pages); if (desired_nr_to_write > max_pages)
In some cases we can reach ext4_da_writepages() with wbc->nr_to_write == LONG_MAX, !range_cyclic, and range_whole=1; in this case we will try to bump it up by a factor of 8, which leads to a desired_nr_to_write value of -8. We still get through the logic without actually changing wbc->nr_to_write because the other tests which would change it don't trip due to the negative value, but it seems dangerous to overflow desired_nr_to_write in the interim, it's not an obvious situation. Signed-off-by: Eric Sandeen <sandeen@redhat.com> --- (V2 minor commit message edits) -- 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