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xfs: create a separate cow extent size hint for the allocator

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Create a per-inode extent size allocator hint for copy-on-write.  This
hint is separate from the existing extent size hint so that CoW can
take advantage of the fragmentation-reducing properties of extent size
hints without disabling delalloc for regular writes.

The extent size hint that's fed to the allocator during a copy on
write operation is the greater of the cowextsize and regular extsize
hint.

During reflink, if we're sharing the entire source file to the entire
destination file and the destination file doesn't already have a
cowextsize hint, propagate the source file's cowextsize hint to the
destination file.

Furthermore, zero the bulkstat buffer prior to setting the fields
so that we don't copy kernel memory contents into userspace.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong
2016-10-03 09:11:43 -07:00
parent 98cc2db5b8
commit f7ca352272
15 changed files with 167 additions and 20 deletions
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67
fs/xfs/xfs_ioctl.c
View File

@@ -903,6 +903,8 @@ xfs_ioc_fsgetxattr(
xfs_ilock(ip, XFS_ILOCK_SHARED);
fa.fsx_xflags = xfs_ip2xflags(ip);
fa.fsx_extsize = ip->i_d.di_extsize << ip->i_mount->m_sb.sb_blocklog;
fa.fsx_cowextsize = ip->i_d.di_cowextsize <<
ip->i_mount->m_sb.sb_blocklog;
fa.fsx_projid = xfs_get_projid(ip);
if (attr) {
@@ -973,12 +975,13 @@ xfs_set_diflags(
if (ip->i_d.di_version < 3)
return;
di_flags2 = 0;
di_flags2 = (ip->i_d.di_flags2 & XFS_DIFLAG2_REFLINK);
if (xflags & FS_XFLAG_DAX)
di_flags2 |= XFS_DIFLAG2_DAX;
if (xflags & FS_XFLAG_COWEXTSIZE)
di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
ip->i_d.di_flags2 = di_flags2;
}
STATIC void
@@ -1219,6 +1222,56 @@ xfs_ioctl_setattr_check_extsize(
return 0;
}
/*
* CoW extent size hint validation rules are:
*
* 1. CoW extent size hint can only be set if reflink is enabled on the fs.
* The inode does not have to have any shared blocks, but it must be a v3.
* 2. FS_XFLAG_COWEXTSIZE is only valid for directories and regular files;
* for a directory, the hint is propagated to new files.
* 3. Can be changed on files & directories at any time.
* 4. CoW extsize hint of 0 turns off hints, clears inode flags.
* 5. Extent size must be a multiple of the appropriate block size.
* 6. The extent size hint must be limited to half the AG size to avoid
* alignment extending the extent beyond the limits of the AG.
*/
static int
xfs_ioctl_setattr_check_cowextsize(
struct xfs_inode *ip,
struct fsxattr *fa)
{
struct xfs_mount *mp = ip->i_mount;
if (!(fa->fsx_xflags & FS_XFLAG_COWEXTSIZE))
return 0;
if (!xfs_sb_version_hasreflink(&ip->i_mount->m_sb) ||
ip->i_d.di_version != 3)
return -EINVAL;
if (!S_ISREG(VFS_I(ip)->i_mode) && !S_ISDIR(VFS_I(ip)->i_mode))
return -EINVAL;
if (fa->fsx_cowextsize != 0) {
xfs_extlen_t size;
xfs_fsblock_t cowextsize_fsb;
cowextsize_fsb = XFS_B_TO_FSB(mp, fa->fsx_cowextsize);
if (cowextsize_fsb > MAXEXTLEN)
return -EINVAL;
size = mp->m_sb.sb_blocksize;
if (cowextsize_fsb > mp->m_sb.sb_agblocks / 2)
return -EINVAL;
if (fa->fsx_cowextsize % size)
return -EINVAL;
} else
fa->fsx_xflags &= ~FS_XFLAG_COWEXTSIZE;
return 0;
}
static int
xfs_ioctl_setattr_check_projid(
struct xfs_inode *ip,
@@ -1311,6 +1364,10 @@ xfs_ioctl_setattr(
if (code)
goto error_trans_cancel;
code = xfs_ioctl_setattr_check_cowextsize(ip, fa);
if (code)
goto error_trans_cancel;
code = xfs_ioctl_setattr_xflags(tp, ip, fa);
if (code)
goto error_trans_cancel;
@@ -1346,6 +1403,12 @@ xfs_ioctl_setattr(
ip->i_d.di_extsize = fa->fsx_extsize >> mp->m_sb.sb_blocklog;
else
ip->i_d.di_extsize = 0;
if (ip->i_d.di_version == 3 &&
(ip->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE))
ip->i_d.di_cowextsize = fa->fsx_cowextsize >>
mp->m_sb.sb_blocklog;
else
ip->i_d.di_cowextsize = 0;
code = xfs_trans_commit(tp);