/*
* Trim the passed in imap to the next shared/unshared extent boundary, and
* if imap->br_startoff points to a shared extent reserve space for it in the
* COW fork. In this case *shared is set to true, else to false.
*
* Note that imap will always contain the block numbers for the existing blocks
* in the data fork, as the upper layers need them for read-modify-write
* operations.
*/
int
xfs_reflink_reserve_cow(
struct xfs_inode *ip,
struct xfs_bmbt_irec *imap,
bool *shared)
{
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
struct xfs_bmbt_irec got;
int error = 0;
bool eof = false, trimmed;
xfs_extnum_t idx;
/*
* Search the COW fork extent list first. This serves two purposes:
* first this implement the speculative preallocation using cowextisze,
* so that we also unshared block adjacent to shared blocks instead
* of just the shared blocks themselves. Second the lookup in the
* extent list is generally faster than going out to the shared extent
* tree.
*/
if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &idx, &got))
eof = true;
if (!eof && got.br_startoff <= imap->br_startoff) {
trace_xfs_reflink_cow_found(ip, imap);
xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
*shared = true;
return 0;
}
/* Trim the mapping to the nearest shared extent boundary. */
error = xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
if (error)
return error;
/* Not shared? Just report the (potentially capped) extent. */
if (!*shared)
return 0;
/*
* Fork all the shared blocks from our write offset until the end of
* the extent.
*/
error = xfs_qm_dqattach_locked(ip, 0);
if (error)
return error;
error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff,
imap->br_blockcount, 0, &got, &idx, eof);
if (error == -ENOSPC || error == -EDQUOT)
trace_xfs_reflink_cow_enospc(ip, imap);
if (error)
return error;
trace_xfs_reflink_cow_alloc(ip, &got);
return 0;
}
bool
xfs_inode_need_cow(
struct xfs_inode *ip,
struct xfs_bmbt_irec *imap,
bool *shared)
{
/* We can't update any real extents in always COW mode. */
if (xfs_is_always_cow_inode(ip) &&
!isnullstartblock(imap->br_startblock)) {
*shared = true;
return 0;
}
/* Trim the mapping to the nearest shared extent boundary. */
return xfs_reflink_trim_around_shared(ip, imap, shared);
}
/* Allocate all CoW reservations covering a range of blocks in a file. */
int
xfs_reflink_allocate_cow(
struct xfs_inode *ip,
struct xfs_bmbt_irec *imap,
bool *shared,
uint *lockmode)
{
struct xfs_mount *mp = ip->i_mount;
xfs_fileoff_t offset_fsb = imap->br_startoff;
xfs_filblks_t count_fsb = imap->br_blockcount;
struct xfs_bmbt_irec got;
struct xfs_defer_ops dfops;
struct xfs_trans *tp = NULL;
xfs_fsblock_t first_block;
int nimaps, error = 0;
bool trimmed;
xfs_filblks_t resaligned;
xfs_extlen_t resblks = 0;
xfs_extnum_t idx;
retry:
ASSERT(xfs_is_reflink_inode(ip));
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
/*
* Even if the extent is not shared we might have a preallocation for
* it in the COW fork. If so use it.
*/
if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &idx, &got) &&
got.br_startoff <= offset_fsb) {
*shared = true;
/* If we have a real allocation in the COW fork we're done. */
if (!isnullstartblock(got.br_startblock)) {
xfs_trim_extent(&got, offset_fsb, count_fsb);
*imap = got;
goto convert;
}
xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
} else {
error = xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
if (error || !*shared)
goto out;
}
if (!tp) {
resaligned = xfs_aligned_fsb_count(imap->br_startoff,
imap->br_blockcount, xfs_get_cowextsz_hint(ip));
resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
xfs_iunlock(ip, *lockmode);
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
*lockmode = XFS_ILOCK_EXCL;
xfs_ilock(ip, *lockmode);
if (error)
return error;
error = xfs_qm_dqattach_locked(ip, 0);
if (error)
goto out;
goto retry;
}
error = xfs_trans_reserve_quota_nblks(tp, ip, resblks, 0,
XFS_QMOPT_RES_REGBLKS);
if (error)
goto out;
xfs_trans_ijoin(tp, ip, 0);
xfs_defer_init(&dfops, &first_block);
nimaps = 1;
/* Allocate the entire reservation as unwritten blocks. */
error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, &first_block,
resblks, imap, &nimaps, &dfops);
if (error)
goto out_bmap_cancel;
/* Finish up. */
error = xfs_defer_finish(&tp, &dfops);
if (error)
goto out_bmap_cancel;
error = xfs_trans_commit(tp);
if (error)
return error;
convert:
return xfs_reflink_convert_cow_extent(ip, imap, offset_fsb, count_fsb,
&dfops);
out_bmap_cancel:
xfs_defer_cancel(&dfops);
xfs_trans_unreserve_quota_nblks(tp, ip, (long)resblks, 0,
XFS_QMOPT_RES_REGBLKS);
out:
if (tp)
xfs_trans_cancel(tp);
return error;
}
