| Submitter | Lukas Czerner |
|---|---|
| Date | July 13, 2012, 1:19 p.m. |
| Message ID | <1342185555-21146-4-git-send-email-lczerner@redhat.com> |
| Download | mbox | patch |
| Permalink | /patch/170888/ |
| State | Superseded |
| Headers | show |
Comments
On Fri, Jul 13, 2012 at 03:19:07PM +0200, Lukas Czerner wrote: > Currently we're passing -1 to truncate_inode_pages_range() which is > actually really confusing since the argument is signed so we do not get > "huge" number as one would expect, but rather just -1. To make things > clearer and easier for truncate_inode_pages_range() just pass LLONG_MAX > since it is actually what was intended anyway. > > It also makes thing easier for allowing truncate_inode_pages_range() to > handle non page aligned regions. Moreover letting the lend argument to > be negative might actually hide some bugs. > > Signed-off-by: Lukas Czerner <lczerner@redhat.com> > Cc: Dave Chinner <dchinner@redhat.com> > --- > fs/xfs/xfs_fs_subr.c | 6 ++++-- > 1 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/fs/xfs/xfs_fs_subr.c b/fs/xfs/xfs_fs_subr.c > index 652b875..6e9b052 100644 > --- a/fs/xfs/xfs_fs_subr.c > +++ b/fs/xfs/xfs_fs_subr.c > @@ -34,7 +34,8 @@ xfs_tosspages( > { > /* can't toss partial tail pages, so mask them out */ > last &= ~(PAGE_SIZE - 1); > - truncate_inode_pages_range(VFS_I(ip)->i_mapping, first, last - 1); > + truncate_inode_pages_range(VFS_I(ip)->i_mapping, first, > + last == -1 ? LLONG_MAX : last); The last paramter changed from (last -1) to last. so if we pass in last = 16384, we now truncate to 16384 (first byte of page index 5) instead of 16383 (last byte of page index 4). That's a change of behaviour and a potential off-by one error, right? > @@ -53,7 +54,8 @@ xfs_flushinval_pages( > ret = filemap_write_and_wait_range(mapping, first, > last == -1 ? LLONG_MAX : last); > if (!ret) > - truncate_inode_pages_range(mapping, first, last); > + truncate_inode_pages_range(mapping, first, > + last == -1 ? LLONG_MAX : last); Given this is also done immediately above in the function, perhaps this should be done before anything: if (last == -1) last = LLONG_MAX; and the parameter simply passed to the two functions without the conditional logic? Cheers, Dave.
On Mon, 16 Jul 2012, Dave Chinner wrote: > Date: Mon, 16 Jul 2012 09:11:17 +1000 > From: Dave Chinner <dchinner@redhat.com> > To: Lukas Czerner <lczerner@redhat.com> > Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, tytso@mit.edu, > achender@linux.vnet.ibm.com > Subject: Re: [PATCH 04/12 v2] xfs: pass LLONG_MAX to > truncate_inode_pages_range > > On Fri, Jul 13, 2012 at 03:19:07PM +0200, Lukas Czerner wrote: > > Currently we're passing -1 to truncate_inode_pages_range() which is > > actually really confusing since the argument is signed so we do not get > > "huge" number as one would expect, but rather just -1. To make things > > clearer and easier for truncate_inode_pages_range() just pass LLONG_MAX > > since it is actually what was intended anyway. > > > > It also makes thing easier for allowing truncate_inode_pages_range() to > > handle non page aligned regions. Moreover letting the lend argument to > > be negative might actually hide some bugs. > > > > Signed-off-by: Lukas Czerner <lczerner@redhat.com> > > Cc: Dave Chinner <dchinner@redhat.com> > > --- > > fs/xfs/xfs_fs_subr.c | 6 ++++-- > > 1 files changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/fs/xfs/xfs_fs_subr.c b/fs/xfs/xfs_fs_subr.c > > index 652b875..6e9b052 100644 > > --- a/fs/xfs/xfs_fs_subr.c > > +++ b/fs/xfs/xfs_fs_subr.c > > @@ -34,7 +34,8 @@ xfs_tosspages( > > { > > /* can't toss partial tail pages, so mask them out */ > > last &= ~(PAGE_SIZE - 1); > > - truncate_inode_pages_range(VFS_I(ip)->i_mapping, first, last - 1); > > + truncate_inode_pages_range(VFS_I(ip)->i_mapping, first, > > + last == -1 ? LLONG_MAX : last); > > The last paramter changed from (last -1) to last. so if we pass in > last = 16384, we now truncate to 16384 (first byte of page index 5) > instead of 16383 (last byte of page index 4). That's a change of > behaviour and a potential off-by one error, right? Right, this could potentially cause off-by-one errors, but as it is now I do not think this could happen. The only place where it is used with a proper range is XFS_IOC_ZERO_RANGE and you're going to convert the whole range to unwritten anyway. But it was unintended and I\ll fix it. > > > @@ -53,7 +54,8 @@ xfs_flushinval_pages( > > ret = filemap_write_and_wait_range(mapping, first, > > last == -1 ? LLONG_MAX : last); > > if (!ret) > > - truncate_inode_pages_range(mapping, first, last); > > + truncate_inode_pages_range(mapping, first, > > + last == -1 ? LLONG_MAX : last); > > Given this is also done immediately above in the function, perhaps > this should be done before anything: > > if (last == -1) > last = LLONG_MAX; > > and the parameter simply passed to the two functions without the > conditional logic? Yes, it makes sense to do this, I'll change it in the next iteration. Thanks for the review Dave. -Lukas > > Cheers, > > Dave. > -- 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, 16 Jul 2012, Lukáš Czerner wrote: > Date: Mon, 16 Jul 2012 09:13:44 +0200 (CEST) > From: Lukáš Czerner <lczerner@redhat.com> > To: Dave Chinner <dchinner@redhat.com> > Cc: Lukas Czerner <lczerner@redhat.com>, linux-ext4@vger.kernel.org, > linux-fsdevel@vger.kernel.org, tytso@mit.edu, achender@linux.vnet.ibm.com > Subject: Re: [PATCH 04/12 v2] xfs: pass LLONG_MAX to > truncate_inode_pages_range > > On Mon, 16 Jul 2012, Dave Chinner wrote: > > > Date: Mon, 16 Jul 2012 09:11:17 +1000 > > From: Dave Chinner <dchinner@redhat.com> > > To: Lukas Czerner <lczerner@redhat.com> > > Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, tytso@mit.edu, > > achender@linux.vnet.ibm.com > > Subject: Re: [PATCH 04/12 v2] xfs: pass LLONG_MAX to > > truncate_inode_pages_range > > > > On Fri, Jul 13, 2012 at 03:19:07PM +0200, Lukas Czerner wrote: > > > Currently we're passing -1 to truncate_inode_pages_range() which is > > > actually really confusing since the argument is signed so we do not get > > > "huge" number as one would expect, but rather just -1. To make things > > > clearer and easier for truncate_inode_pages_range() just pass LLONG_MAX > > > since it is actually what was intended anyway. > > > > > > It also makes thing easier for allowing truncate_inode_pages_range() to > > > handle non page aligned regions. Moreover letting the lend argument to > > > be negative might actually hide some bugs. > > > > > > Signed-off-by: Lukas Czerner <lczerner@redhat.com> > > > Cc: Dave Chinner <dchinner@redhat.com> > > > --- > > > fs/xfs/xfs_fs_subr.c | 6 ++++-- > > > 1 files changed, 4 insertions(+), 2 deletions(-) > > > > > > diff --git a/fs/xfs/xfs_fs_subr.c b/fs/xfs/xfs_fs_subr.c > > > index 652b875..6e9b052 100644 > > > --- a/fs/xfs/xfs_fs_subr.c > > > +++ b/fs/xfs/xfs_fs_subr.c > > > @@ -34,7 +34,8 @@ xfs_tosspages( > > > { > > > /* can't toss partial tail pages, so mask them out */ > > > last &= ~(PAGE_SIZE - 1); > > > - truncate_inode_pages_range(VFS_I(ip)->i_mapping, first, last - 1); > > > + truncate_inode_pages_range(VFS_I(ip)->i_mapping, first, > > > + last == -1 ? LLONG_MAX : last); > > > > The last paramter changed from (last -1) to last. so if we pass in > > last = 16384, we now truncate to 16384 (first byte of page index 5) > > instead of 16383 (last byte of page index 4). That's a change of > > behaviour and a potential off-by one error, right? > > Right, this could potentially cause off-by-one errors, but as it is > now I do not think this could happen. The only place where it is > used with a proper range is XFS_IOC_ZERO_RANGE and you're going to > convert the whole range to unwritten anyway. But it was unintended > and I\ll fix it. Hi Dave, Is there a reason for aligning the last page in the xfs_tosspages() other than truncate_inode_pages_range() does not handle unaligned regions ? Because with my patch it does now, so it seems to me that we can easily get rid of the xfs_tosspages() and just use truncate_inode_pages_range() instead in xfs_change_file_space() and xfs_swap_extents(). Thanks! -Lukas > > > > > > > @@ -53,7 +54,8 @@ xfs_flushinval_pages( > > > ret = filemap_write_and_wait_range(mapping, first, > > > last == -1 ? LLONG_MAX : last); > > > if (!ret) > > > - truncate_inode_pages_range(mapping, first, last); > > > + truncate_inode_pages_range(mapping, first, > > > + last == -1 ? LLONG_MAX : last); > > > > Given this is also done immediately above in the function, perhaps > > this should be done before anything: > > > > if (last == -1) > > last = LLONG_MAX; > > > > and the parameter simply passed to the two functions without the > > conditional logic? > > Yes, it makes sense to do this, I'll change it in the next > iteration. > > Thanks for the review Dave. > -Lukas > > > > > Cheers, > > > > Dave. > > >
Patch
diff --git a/fs/xfs/xfs_fs_subr.c b/fs/xfs/xfs_fs_subr.c index 652b875..6e9b052 100644 --- a/fs/xfs/xfs_fs_subr.c +++ b/fs/xfs/xfs_fs_subr.c @@ -34,7 +34,8 @@ xfs_tosspages( { /* can't toss partial tail pages, so mask them out */ last &= ~(PAGE_SIZE - 1); - truncate_inode_pages_range(VFS_I(ip)->i_mapping, first, last - 1); + truncate_inode_pages_range(VFS_I(ip)->i_mapping, first, + last == -1 ? LLONG_MAX : last); } int @@ -53,7 +54,8 @@ xfs_flushinval_pages( ret = filemap_write_and_wait_range(mapping, first, last == -1 ? LLONG_MAX : last); if (!ret) - truncate_inode_pages_range(mapping, first, last); + truncate_inode_pages_range(mapping, first, + last == -1 ? LLONG_MAX : last); return -ret; }
Currently we're passing -1 to truncate_inode_pages_range() which is actually really confusing since the argument is signed so we do not get "huge" number as one would expect, but rather just -1. To make things clearer and easier for truncate_inode_pages_range() just pass LLONG_MAX since it is actually what was intended anyway. It also makes thing easier for allowing truncate_inode_pages_range() to handle non page aligned regions. Moreover letting the lend argument to be negative might actually hide some bugs. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Cc: Dave Chinner <dchinner@redhat.com> --- fs/xfs/xfs_fs_subr.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-)