diff options
Diffstat (limited to 'fs/xfs/xfs_reflink.c')
| -rw-r--r-- | fs/xfs/xfs_reflink.c | 1688 |
1 files changed, 1688 insertions, 0 deletions
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c new file mode 100644 index 000000000000..5965e9455d91 --- /dev/null +++ b/fs/xfs/xfs_reflink.c @@ -0,0 +1,1688 @@ +/* + * Copyright (C) 2016 Oracle. All Rights Reserved. + * + * Author: Darrick J. Wong <[email protected]> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it would be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. + */ +#include "xfs.h" +#include "xfs_fs.h" +#include "xfs_shared.h" +#include "xfs_format.h" +#include "xfs_log_format.h" +#include "xfs_trans_resv.h" +#include "xfs_mount.h" +#include "xfs_defer.h" +#include "xfs_da_format.h" +#include "xfs_da_btree.h" +#include "xfs_inode.h" +#include "xfs_trans.h" +#include "xfs_inode_item.h" +#include "xfs_bmap.h" +#include "xfs_bmap_util.h" +#include "xfs_error.h" +#include "xfs_dir2.h" +#include "xfs_dir2_priv.h" +#include "xfs_ioctl.h" +#include "xfs_trace.h" +#include "xfs_log.h" +#include "xfs_icache.h" +#include "xfs_pnfs.h" +#include "xfs_btree.h" +#include "xfs_refcount_btree.h" +#include "xfs_refcount.h" +#include "xfs_bmap_btree.h" +#include "xfs_trans_space.h" +#include "xfs_bit.h" +#include "xfs_alloc.h" +#include "xfs_quota_defs.h" +#include "xfs_quota.h" +#include "xfs_btree.h" +#include "xfs_bmap_btree.h" +#include "xfs_reflink.h" +#include "xfs_iomap.h" +#include "xfs_rmap_btree.h" +#include "xfs_sb.h" +#include "xfs_ag_resv.h" + +/* + * Copy on Write of Shared Blocks + * + * XFS must preserve "the usual" file semantics even when two files share + * the same physical blocks. This means that a write to one file must not + * alter the blocks in a different file; the way that we'll do that is + * through the use of a copy-on-write mechanism. At a high level, that + * means that when we want to write to a shared block, we allocate a new + * block, write the data to the new block, and if that succeeds we map the + * new block into the file. + * + * XFS provides a "delayed allocation" mechanism that defers the allocation + * of disk blocks to dirty-but-not-yet-mapped file blocks as long as + * possible. This reduces fragmentation by enabling the filesystem to ask + * for bigger chunks less often, which is exactly what we want for CoW. + * + * The delalloc mechanism begins when the kernel wants to make a block + * writable (write_begin or page_mkwrite). If the offset is not mapped, we + * create a delalloc mapping, which is a regular in-core extent, but without + * a real startblock. (For delalloc mappings, the startblock encodes both + * a flag that this is a delalloc mapping, and a worst-case estimate of how + * many blocks might be required to put the mapping into the BMBT.) delalloc + * mappings are a reservation against the free space in the filesystem; + * adjacent mappings can also be combined into fewer larger mappings. + * + * When dirty pages are being written out (typically in writepage), the + * delalloc reservations are converted into real mappings by allocating + * blocks and replacing the delalloc mapping with real ones. A delalloc + * mapping can be replaced by several real ones if the free space is + * fragmented. + * + * We want to adapt the delalloc mechanism for copy-on-write, since the + * write paths are similar. The first two steps (creating the reservation + * and allocating the blocks) are exactly the same as delalloc except that + * the mappings must be stored in a separate CoW fork because we do not want + * to disturb the mapping in the data fork until we're sure that the write + * succeeded. IO completion in this case is the process of removing the old + * mapping from the data fork and moving the new mapping from the CoW fork to + * the data fork. This will be discussed shortly. + * + * For now, unaligned directio writes will be bounced back to the page cache. + * Block-aligned directio writes will use the same mechanism as buffered + * writes. + * + * CoW remapping must be done after the data block write completes, + * because we don't want to destroy the old data fork map until we're sure + * the new block has been written. Since the new mappings are kept in a + * separate fork, we can simply iterate these mappings to find the ones + * that cover the file blocks that we just CoW'd. For each extent, simply + * unmap the corresponding range in the data fork, map the new range into + * the data fork, and remove the extent from the CoW fork. + * + * Since the remapping operation can be applied to an arbitrary file + * range, we record the need for the remap step as a flag in the ioend + * instead of declaring a new IO type. This is required for direct io + * because we only have ioend for the whole dio, and we have to be able to + * remember the presence of unwritten blocks and CoW blocks with a single + * ioend structure. Better yet, the more ground we can cover with one + * ioend, the better. + */ + +/* + * Given an AG extent, find the lowest-numbered run of shared blocks + * within that range and return the range in fbno/flen. If + * find_end_of_shared is true, return the longest contiguous extent of + * shared blocks. If there are no shared extents, fbno and flen will + * be set to NULLAGBLOCK and 0, respectively. + */ +int +xfs_reflink_find_shared( + struct xfs_mount *mp, + xfs_agnumber_t agno, + xfs_agblock_t agbno, + xfs_extlen_t aglen, + xfs_agblock_t *fbno, + xfs_extlen_t *flen, + bool find_end_of_shared) +{ + struct xfs_buf *agbp; + struct xfs_btree_cur *cur; + int error; + + error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp); + if (error) + return error; + + cur = xfs_refcountbt_init_cursor(mp, NULL, agbp, agno, NULL); + + error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen, + find_end_of_shared); + + xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR); + + xfs_buf_relse(agbp); + return error; +} + +/* + * Trim the mapping to the next block where there's a change in the + * shared/unshared status. More specifically, this means that we + * find the lowest-numbered extent of shared blocks that coincides with + * the given block mapping. If the shared extent overlaps the start of + * the mapping, trim the mapping to the end of the shared extent. If + * the shared region intersects the mapping, trim the mapping to the + * start of the shared extent. If there are no shared regions that + * overlap, just return the original extent. + */ +int +xfs_reflink_trim_around_shared( + struct xfs_inode *ip, + struct xfs_bmbt_irec *irec, + bool *shared, + bool *trimmed) +{ + xfs_agnumber_t agno; + xfs_agblock_t agbno; + xfs_extlen_t aglen; + xfs_agblock_t fbno; + xfs_extlen_t flen; + int error = 0; + + /* Holes, unwritten, and delalloc extents cannot be shared */ + if (!xfs_is_reflink_inode(ip) || + ISUNWRITTEN(irec) || + irec->br_startblock == HOLESTARTBLOCK || + irec->br_startblock == DELAYSTARTBLOCK) { + *shared = false; + return 0; + } + + trace_xfs_reflink_trim_around_shared(ip, irec); + + agno = XFS_FSB_TO_AGNO(ip->i_mount, irec->br_startblock); + agbno = XFS_FSB_TO_AGBNO(ip->i_mount, irec->br_startblock); + aglen = irec->br_blockcount; + + error = xfs_reflink_find_shared(ip->i_mount, agno, agbno, + aglen, &fbno, &flen, true); + if (error) + return error; + + *shared = *trimmed = false; + if (fbno == NULLAGBLOCK) { + /* No shared blocks at all. */ + return 0; + } else if (fbno == agbno) { + /* + * The start of this extent is shared. Truncate the + * mapping at the end of the shared region so that a + * subsequent iteration starts at the start of the + * unshared region. + */ + irec->br_blockcount = flen; + *shared = true; + if (flen != aglen) + *trimmed = true; + return 0; + } else { + /* + * There's a shared extent midway through this extent. + * Truncate the mapping at the start of the shared + * extent so that a subsequent iteration starts at the + * start of the shared region. + */ + irec->br_blockcount = fbno - agbno; + *trimmed = true; + return 0; + } +} + +/* Create a CoW reservation for a range of blocks within a file. */ +static int +__xfs_reflink_reserve_cow( + struct xfs_inode *ip, + xfs_fileoff_t *offset_fsb, + xfs_fileoff_t end_fsb, + bool *skipped) +{ + struct xfs_bmbt_irec got, prev, imap; + xfs_fileoff_t orig_end_fsb; + int nimaps, eof = 0, error = 0; + bool shared = false, trimmed = false; + xfs_extnum_t idx; + xfs_extlen_t align; + + /* Already reserved? Skip the refcount btree access. */ + xfs_bmap_search_extents(ip, *offset_fsb, XFS_COW_FORK, &eof, &idx, + &got, &prev); + if (!eof && got.br_startoff <= *offset_fsb) { + end_fsb = orig_end_fsb = got.br_startoff + got.br_blockcount; + trace_xfs_reflink_cow_found(ip, &got); + goto done; + } + + /* Read extent from the source file. */ + nimaps = 1; + error = xfs_bmapi_read(ip, *offset_fsb, end_fsb - *offset_fsb, + &imap, &nimaps, 0); + if (error) + goto out_unlock; + ASSERT(nimaps == 1); + + /* Trim the mapping to the nearest shared extent boundary. */ + error = xfs_reflink_trim_around_shared(ip, &imap, &shared, &trimmed); + if (error) + goto out_unlock; + + end_fsb = orig_end_fsb = imap.br_startoff + imap.br_blockcount; + + /* Not shared? Just report the (potentially capped) extent. */ + if (!shared) { + *skipped = true; + goto done; + } + + /* + * Fork all the shared blocks from our write offset until the end of + * the extent. + */ + error = xfs_qm_dqattach_locked(ip, 0); + if (error) + goto out_unlock; + + align = xfs_eof_alignment(ip, xfs_get_cowextsz_hint(ip)); + if (align) + end_fsb = roundup_64(end_fsb, align); + +retry: + error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, *offset_fsb, + end_fsb - *offset_fsb, &got, + &prev, &idx, eof); + switch (error) { + case 0: + break; + case -ENOSPC: + case -EDQUOT: + /* retry without any preallocation */ + trace_xfs_reflink_cow_enospc(ip, &imap); + if (end_fsb != orig_end_fsb) { + end_fsb = orig_end_fsb; + goto retry; + } + /*FALLTHRU*/ + default: + goto out_unlock; + } + + if (end_fsb != orig_end_fsb) + xfs_inode_set_cowblocks_tag(ip); + + trace_xfs_reflink_cow_alloc(ip, &got); +done: + *offset_fsb = end_fsb; +out_unlock: + return error; +} + +/* Create a CoW reservation for part of a file. */ +int +xfs_reflink_reserve_cow_range( + struct xfs_inode *ip, + xfs_off_t offset, + xfs_off_t count) +{ + struct xfs_mount *mp = ip->i_mount; + xfs_fileoff_t offset_fsb, end_fsb; + bool skipped = false; + int error; + + trace_xfs_reflink_reserve_cow_range(ip, offset, count); + + offset_fsb = XFS_B_TO_FSBT(mp, offset); + end_fsb = XFS_B_TO_FSB(mp, offset + count); + + xfs_ilock(ip, XFS_ILOCK_EXCL); + while (offset_fsb < end_fsb) { + error = __xfs_reflink_reserve_cow(ip, &offset_fsb, end_fsb, + &skipped); + if (error) { + trace_xfs_reflink_reserve_cow_range_error(ip, error, + _RET_IP_); + break; + } + } + xfs_iunlock(ip, XFS_ILOCK_EXCL); + + return error; +} + +/* Allocate all CoW reservations covering a range of blocks in a file. */ +static int +__xfs_reflink_allocate_cow( + struct xfs_inode *ip, + xfs_fileoff_t *offset_fsb, + xfs_fileoff_t end_fsb) +{ + struct xfs_mount *mp = ip->i_mount; + struct xfs_bmbt_irec imap; + struct xfs_defer_ops dfops; + struct xfs_trans *tp; + xfs_fsblock_t first_block; + xfs_fileoff_t next_fsb; + int nimaps = 1, error; + bool skipped = false; + + xfs_defer_init(&dfops, &first_block); + + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, + XFS_TRANS_RESERVE, &tp); + if (error) + return error; + + xfs_ilock(ip, XFS_ILOCK_EXCL); + + next_fsb = *offset_fsb; + error = __xfs_reflink_reserve_cow(ip, &next_fsb, end_fsb, &skipped); + if (error) + goto out_trans_cancel; + + if (skipped) { + *offset_fsb = next_fsb; + goto out_trans_cancel; + } + + xfs_trans_ijoin(tp, ip, 0); + error = xfs_bmapi_write(tp, ip, *offset_fsb, next_fsb - *offset_fsb, + XFS_BMAPI_COWFORK, &first_block, + XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK), + &imap, &nimaps, &dfops); + if (error) + goto out_trans_cancel; + + /* We might not have been able to map the whole delalloc extent */ + *offset_fsb = min(*offset_fsb + imap.br_blockcount, next_fsb); + + error = xfs_defer_finish(&tp, &dfops, NULL); + if (error) + goto out_trans_cancel; + + error = xfs_trans_commit(tp); + +out_unlock: + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return error; +out_trans_cancel: + xfs_defer_cancel(&dfops); + xfs_trans_cancel(tp); + goto out_unlock; +} + +/* Allocate all CoW reservations covering a part of a file. */ +int +xfs_reflink_allocate_cow_range( + struct xfs_inode *ip, + xfs_off_t offset, + xfs_off_t count) +{ + struct xfs_mount *mp = ip->i_mount; + xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset); + xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count); + int error; + + ASSERT(xfs_is_reflink_inode(ip)); + + trace_xfs_reflink_allocate_cow_range(ip, offset, count); + + /* + * Make sure that the dquots are there. + */ + error = xfs_qm_dqattach(ip, 0); + if (error) + return error; + + while (offset_fsb < end_fsb) { + error = __xfs_reflink_allocate_cow(ip, &offset_fsb, end_fsb); + if (error) { + trace_xfs_reflink_allocate_cow_range_error(ip, error, + _RET_IP_); + break; + } + } + + return error; +} + +/* + * Find the CoW reservation (and whether or not it needs block allocation) + * for a given byte offset of a file. + */ +bool +xfs_reflink_find_cow_mapping( + struct xfs_inode *ip, + xfs_off_t offset, + struct xfs_bmbt_irec *imap, + bool *need_alloc) +{ + struct xfs_bmbt_irec irec; + struct xfs_ifork *ifp; + struct xfs_bmbt_rec_host *gotp; + xfs_fileoff_t bno; + xfs_extnum_t idx; + + ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED)); + ASSERT(xfs_is_reflink_inode(ip)); + + /* Find the extent in the CoW fork. */ + ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); + bno = XFS_B_TO_FSBT(ip->i_mount, offset); + gotp = xfs_iext_bno_to_ext(ifp, bno, &idx); + if (!gotp) + return false; + + xfs_bmbt_get_all(gotp, &irec); + if (bno >= irec.br_startoff + irec.br_blockcount || + bno < irec.br_startoff) + return false; + + trace_xfs_reflink_find_cow_mapping(ip, offset, 1, XFS_IO_OVERWRITE, + &irec); + + /* If it's still delalloc, we must allocate later. */ + *imap = irec; + *need_alloc = !!(isnullstartblock(irec.br_startblock)); + + return true; +} + +/* + * Trim an extent to end at the next CoW reservation past offset_fsb. + */ +int +xfs_reflink_trim_irec_to_next_cow( + struct xfs_inode *ip, + xfs_fileoff_t offset_fsb, + struct xfs_bmbt_irec *imap) +{ + struct xfs_bmbt_irec irec; + struct xfs_ifork *ifp; + struct xfs_bmbt_rec_host *gotp; + xfs_extnum_t idx; + + if (!xfs_is_reflink_inode(ip)) + return 0; + + /* Find the extent in the CoW fork. */ + ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); + gotp = xfs_iext_bno_to_ext(ifp, offset_fsb, &idx); + if (!gotp) + return 0; + xfs_bmbt_get_all(gotp, &irec); + + /* This is the extent before; try sliding up one. */ + if (irec.br_startoff < offset_fsb) { + idx++; + if (idx >= ifp->if_bytes / sizeof(xfs_bmbt_rec_t)) + return 0; + gotp = xfs_iext_get_ext(ifp, idx); + xfs_bmbt_get_all(gotp, &irec); + } + + if (irec.br_startoff >= imap->br_startoff + imap->br_blockcount) + return 0; + + imap->br_blockcount = irec.br_startoff - imap->br_startoff; + trace_xfs_reflink_trim_irec(ip, imap); + + return 0; +} + +/* + * Cancel all pending CoW reservations for some block range of an inode. + */ +int +xfs_reflink_cancel_cow_blocks( + struct xfs_inode *ip, + struct xfs_trans **tpp, + xfs_fileoff_t offset_fsb, + xfs_fileoff_t end_fsb) +{ + struct xfs_bmbt_irec irec; + xfs_filblks_t count_fsb; + xfs_fsblock_t firstfsb; + struct xfs_defer_ops dfops; + int error = 0; + int nimaps; + + if (!xfs_is_reflink_inode(ip)) + return 0; + + /* Go find the old extent in the CoW fork. */ + while (offset_fsb < end_fsb) { + nimaps = 1; + count_fsb = (xfs_filblks_t)(end_fsb - offset_fsb); + error = xfs_bmapi_read(ip, offset_fsb, count_fsb, &irec, + &nimaps, XFS_BMAPI_COWFORK); + if (error) + break; + ASSERT(nimaps == 1); + + trace_xfs_reflink_cancel_cow(ip, &irec); + + if (irec.br_startblock == DELAYSTARTBLOCK) { + /* Free a delayed allocation. */ + xfs_mod_fdblocks(ip->i_mount, irec.br_blockcount, + false); + ip->i_delayed_blks -= irec.br_blockcount; + + /* Remove the mapping from the CoW fork. */ + error = xfs_bunmapi_cow(ip, &irec); + if (error) + break; + } else if (irec.br_startblock == HOLESTARTBLOCK) { + /* empty */ + } else { + xfs_trans_ijoin(*tpp, ip, 0); + xfs_defer_init(&dfops, &firstfsb); + + /* Free the CoW orphan record. */ + error = xfs_refcount_free_cow_extent(ip->i_mount, + &dfops, irec.br_startblock, + irec.br_blockcount); + if (error) + break; + + xfs_bmap_add_free(ip->i_mount, &dfops, + irec.br_startblock, irec.br_blockcount, + NULL); + + /* Update quota accounting */ + xfs_trans_mod_dquot_byino(*tpp, ip, XFS_TRANS_DQ_BCOUNT, + -(long)irec.br_blockcount); + + /* Roll the transaction */ + error = xfs_defer_finish(tpp, &dfops, ip); + if (error) { + xfs_defer_cancel(&dfops); + break; + } + + /* Remove the mapping from the CoW fork. */ + error = xfs_bunmapi_cow(ip, &irec); + if (error) + break; + } + + /* Roll on... */ + offset_fsb = irec.br_startoff + irec.br_blockcount; + } + + return error; +} + +/* + * Cancel all pending CoW reservations for some byte range of an inode. + */ +int +xfs_reflink_cancel_cow_range( + struct xfs_inode *ip, + xfs_off_t offset, + xfs_off_t count) +{ + struct xfs_trans *tp; + xfs_fileoff_t offset_fsb; + xfs_fileoff_t end_fsb; + int error; + + trace_xfs_reflink_cancel_cow_range(ip, offset, count); + ASSERT(xfs_is_reflink_inode(ip)); + + offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset); + if (count == NULLFILEOFF) + end_fsb = NULLFILEOFF; + else + end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count); + + /* Start a rolling transaction to remove the mappings */ + error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write, + 0, 0, 0, &tp); + if (error) + goto out; + + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, ip, 0); + + /* Scrape out the old CoW reservations */ + error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb); + if (error) + goto out_cancel; + + error = xfs_trans_commit(tp); + + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return error; + +out_cancel: + xfs_trans_cancel(tp); + xfs_iunlock(ip, XFS_ILOCK_EXCL); +out: + trace_xfs_reflink_cancel_cow_range_error(ip, error, _RET_IP_); + return error; +} + +/* + * Remap parts of a file's data fork after a successful CoW. + */ +int +xfs_reflink_end_cow( + struct xfs_inode *ip, + xfs_off_t offset, + xfs_off_t count) +{ + struct xfs_bmbt_irec irec; + struct xfs_bmbt_irec uirec; + struct xfs_trans *tp; + xfs_fileoff_t offset_fsb; + xfs_fileoff_t end_fsb; + xfs_filblks_t count_fsb; + xfs_fsblock_t firstfsb; + struct xfs_defer_ops dfops; + int error; + unsigned int resblks; + xfs_filblks_t ilen; + xfs_filblks_t rlen; + int nimaps; + + trace_xfs_reflink_end_cow(ip, offset, count); + + offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset); + end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count); + count_fsb = (xfs_filblks_t)(end_fsb - offset_fsb); + + /* Start a rolling transaction to switch the mappings */ + resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK); + error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write, + resblks, 0, 0, &tp); + if (error) + goto out; + + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, ip, 0); + + /* Go find the old extent in the CoW fork. */ + while (offset_fsb < end_fsb) { + /* Read extent from the source file */ + nimaps = 1; + count_fsb = (xfs_filblks_t)(end_fsb - offset_fsb); + error = xfs_bmapi_read(ip, offset_fsb, count_fsb, &irec, + &nimaps, XFS_BMAPI_COWFORK); + if (error) + goto out_cancel; + ASSERT(nimaps == 1); + + ASSERT(irec.br_startblock != DELAYSTARTBLOCK); + trace_xfs_reflink_cow_remap(ip, &irec); + + /* + * We can have a hole in the CoW fork if part of a directio + * write is CoW but part of it isn't. + */ + rlen = ilen = irec.br_blockcount; + if (irec.br_startblock == HOLESTARTBLOCK) + goto next_extent; + + /* Unmap the old blocks in the data fork. */ + while (rlen) { + xfs_defer_init(&dfops, &firstfsb); + error = __xfs_bunmapi(tp, ip, irec.br_startoff, + &rlen, 0, 1, &firstfsb, &dfops); + if (error) + goto out_defer; + + /* + * Trim the extent to whatever got unmapped. + * Remember, bunmapi works backwards. + */ + uirec.br_startblock = irec.br_startblock + rlen; + uirec.br_startoff = irec.br_startoff + rlen; + uirec.br_blockcount = irec.br_blockcount - rlen; + irec.br_blockcount = rlen; + trace_xfs_reflink_cow_remap_piece(ip, &uirec); + + /* Free the CoW orphan record. */ + error = xfs_refcount_free_cow_extent(tp->t_mountp, + &dfops, uirec.br_startblock, + uirec.br_blockcount); + if (error) + goto out_defer; + + /* Map the new blocks into the data fork. */ + error = xfs_bmap_map_extent(tp->t_mountp, &dfops, + ip, &uirec); + if (error) + goto out_defer; + + /* Remove the mapping from the CoW fork. */ + error = xfs_bunmapi_cow(ip, &uirec); + if (error) + goto out_defer; + + error = xfs_defer_finish(&tp, &dfops, ip); + if (error) + goto out_defer; + } + +next_extent: + /* Roll on... */ + offset_fsb = irec.br_startoff + ilen; + } + + error = xfs_trans_commit(tp); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + if (error) + goto out; + return 0; + +out_defer: + xfs_defer_cancel(&dfops); +out_cancel: + xfs_trans_cancel(tp); + xfs_iunlock(ip, XFS_ILOCK_EXCL); +out: + trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_); + return error; +} + +/* + * Free leftover CoW reservations that didn't get cleaned out. + */ +int +xfs_reflink_recover_cow( + struct xfs_mount *mp) +{ + xfs_agnumber_t agno; + int error = 0; + + if (!xfs_sb_version_hasreflink(&mp->m_sb)) + return 0; + + for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) { + error = xfs_refcount_recover_cow_leftovers(mp, agno); + if (error) + break; + } + + return error; +} + +/* + * Reflinking (Block) Ranges of Two Files Together + * + * First, ensure that the reflink flag is set on both inodes. The flag is an + * optimization to avoid unnecessary refcount btree lookups in the write path. + * + * Now we can iteratively remap the range of extents (and holes) in src to the + * corresponding ranges in dest. Let drange and srange denote the ranges of + * logical blocks in dest and src touched by the reflink operation. + * + * While the length of drange is greater than zero, + * - Read src's bmbt at the start of srange ("imap") + * - If imap doesn't exist, make imap appear to start at the end of srange + * with zero length. + * - If imap starts before srange, advance imap to start at srange. + * - If imap goes beyond srange, truncate imap to end at the end of srange. + * - Punch (imap start - srange start + imap len) blocks from dest at + * offset (drange start). + * - If imap points to a real range of pblks, + * > Increase the refcount of the imap's pblks + * > Map imap's pblks into dest at the offset + * (drange start + imap start - srange start) + * - Advance drange and srange by (imap start - srange start + imap len) + * + * Finally, if the reflink made dest longer, update both the in-core and + * on-disk file sizes. + * + * ASCII Art Demonstration: + * + * Let's say we want to reflink this source file: + * + * ----SSSSSSS-SSSSS----SSSSSS (src file) + * <--------------------> + * + * into this destination file: + * + * --DDDDDDDDDDDDDDDDDDD--DDD (dest file) + * <--------------------> + * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest. + * Observe that the range has different logical offsets in either file. + * + * Consider that the first extent in the source file doesn't line up with our + * reflink range. Unmapping and remapping are separate operations, so we can + * unmap more blocks from the destination file than we remap. + * + * ----SSSSSSS-SSSSS----SSSSSS + * <-------> + * --DDDDD---------DDDDD--DDD + * <-------> + * + * Now remap the source extent into the destination file: + * + * ----SSSSSSS-SSSSS----SSSSSS + * <-------> + * --DDDDD--SSSSSSSDDDDD--DDD + * <-------> + * + * Do likewise with the second hole and extent in our range. Holes in the + * unmap range don't affect our operation. + * + * ----SSSSSSS-SSSSS----SSSSSS + * <----> + * --DDDDD--SSSSSSS-SSSSS-DDD + * <----> + * + * Finally, unmap and remap part of the third extent. This will increase the + * size of the destination file. + * + * ----SSSSSSS-SSSSS----SSSSSS + * <-----> + * --DDDDD--SSSSSSS-SSSSS----SSS + * <-----> + * + * Once we update the destination file's i_size, we're done. + */ + +/* + * Ensure the reflink bit is set in both inodes. + */ +STATIC int +xfs_reflink_set_inode_flag( + struct xfs_inode *src, + struct xfs_inode *dest) +{ + struct xfs_mount *mp = src->i_mount; + int error; + struct xfs_trans *tp; + + if (xfs_is_reflink_inode(src) && xfs_is_reflink_inode(dest)) + return 0; + + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp); + if (error) + goto out_error; + + /* Lock both files against IO */ + if (src->i_ino == dest->i_ino) + xfs_ilock(src, XFS_ILOCK_EXCL); + else + xfs_lock_two_inodes(src, dest, XFS_ILOCK_EXCL); + + if (!xfs_is_reflink_inode(src)) { + trace_xfs_reflink_set_inode_flag(src); + xfs_trans_ijoin(tp, src, XFS_ILOCK_EXCL); + src->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK; + xfs_trans_log_inode(tp, src, XFS_ILOG_CORE); + xfs_ifork_init_cow(src); + } else + xfs_iunlock(src, XFS_ILOCK_EXCL); + + if (src->i_ino == dest->i_ino) + goto commit_flags; + + if (!xfs_is_reflink_inode(dest)) { + trace_xfs_reflink_set_inode_flag(dest); + xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL); + dest->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK; + xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE); + xfs_ifork_init_cow(dest); + } else + xfs_iunlock(dest, XFS_ILOCK_EXCL); + +commit_flags: + error = xfs_trans_commit(tp); + if (error) + goto out_error; + return error; + +out_error: + trace_xfs_reflink_set_inode_flag_error(dest, error, _RET_IP_); + return error; +} + +/* + * Update destination inode size & cowextsize hint, if necessary. + */ +STATIC int +xfs_reflink_update_dest( + struct xfs_inode *dest, + xfs_off_t newlen, + xfs_extlen_t cowextsize) +{ + struct xfs_mount *mp = dest->i_mount; + struct xfs_trans *tp; + int error; + + if (newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0) + return 0; + + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp); + if (error) + goto out_error; + + xfs_ilock(dest, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL); + + if (newlen > i_size_read(VFS_I(dest))) { + trace_xfs_reflink_update_inode_size(dest, newlen); + i_size_write(VFS_I(dest), newlen); + dest->i_d.di_size = newlen; + } + + if (cowextsize) { + dest->i_d.di_cowextsize = cowextsize; + dest->i_d.di_flags2 |= XFS_DIFLAG2_COWEXTSIZE; + } + + xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE); + + error = xfs_trans_commit(tp); + if (error) + goto out_error; + return error; + +out_error: + trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_); + return error; +} + +/* + * Do we have enough reserve in this AG to handle a reflink? The refcount + * btree already reserved all the space it needs, but the rmap btree can grow + * infinitely, so we won't allow more reflinks when the AG is down to the + * btree reserves. + */ +static int +xfs_reflink_ag_has_free_space( + struct xfs_mount *mp, + xfs_agnumber_t agno) +{ + struct xfs_perag *pag; + int error = 0; + + if (!xfs_sb_version_hasrmapbt(&mp->m_sb)) + return 0; + + pag = xfs_perag_get(mp, agno); + if (xfs_ag_resv_critical(pag, XFS_AG_RESV_AGFL) || + xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA)) + error = -ENOSPC; + xfs_perag_put(pag); + return error; +} + +/* + * Unmap a range of blocks from a file, then map other blocks into the hole. + * The range to unmap is (destoff : destoff + srcioff + irec->br_blockcount). + * The extent irec is mapped into dest at irec->br_startoff. + */ +STATIC int +xfs_reflink_remap_extent( + struct xfs_inode *ip, + struct xfs_bmbt_irec *irec, + xfs_fileoff_t destoff, + xfs_off_t new_isize) +{ + struct xfs_mount *mp = ip->i_mount; + struct xfs_trans *tp; + xfs_fsblock_t firstfsb; + unsigned int resblks; + struct xfs_defer_ops dfops; + struct xfs_bmbt_irec uirec; + bool real_extent; + xfs_filblks_t rlen; + xfs_filblks_t unmap_len; + xfs_off_t newlen; + int error; + + unmap_len = irec->br_startoff + irec->br_blockcount - destoff; + trace_xfs_reflink_punch_range(ip, destoff, unmap_len); + + /* Only remap normal extents. */ + real_extent = (irec->br_startblock != HOLESTARTBLOCK && + irec->br_startblock != DELAYSTARTBLOCK && + !ISUNWRITTEN(irec)); + + /* No reflinking if we're low on space */ + if (real_extent) { + error = xfs_reflink_ag_has_free_space(mp, + XFS_FSB_TO_AGNO(mp, irec->br_startblock)); + if (error) + goto out; + } + + /* Start a rolling transaction to switch the mappings */ + resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK); + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp); + if (error) + goto out; + + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, ip, 0); + + /* If we're not just clearing space, then do we have enough quota? */ + if (real_extent) { + error = xfs_trans_reserve_quota_nblks(tp, ip, + irec->br_blockcount, 0, XFS_QMOPT_RES_REGBLKS); + if (error) + goto out_cancel; + } + + trace_xfs_reflink_remap(ip, irec->br_startoff, + irec->br_blockcount, irec->br_startblock); + + /* Unmap the old blocks in the data fork. */ + rlen = unmap_len; + while (rlen) { + xfs_defer_init(&dfops, &firstfsb); + error = __xfs_bunmapi(tp, ip, destoff, &rlen, 0, 1, + &firstfsb, &dfops); + if (error) + goto out_defer; + + /* + * Trim the extent to whatever got unmapped. + * Remember, bunmapi works backwards. + */ + uirec.br_startblock = irec->br_startblock + rlen; + uirec.br_startoff = irec->br_startoff + rlen; + uirec.br_blockcount = unmap_len - rlen; + unmap_len = rlen; + + /* If this isn't a real mapping, we're done. */ + if (!real_extent || uirec.br_blockcount == 0) + goto next_extent; + + trace_xfs_reflink_remap(ip, uirec.br_startoff, + uirec.br_blockcount, uirec.br_startblock); + + /* Update the refcount tree */ + error = xfs_refcount_increase_extent(mp, &dfops, &uirec); + if (error) + goto out_defer; + + /* Map the new blocks into the data fork. */ + error = xfs_bmap_map_extent(mp, &dfops, ip, &uirec); + if (error) + goto out_defer; + + /* Update quota accounting. */ + xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, + uirec.br_blockcount); + + /* Update dest isize if needed. */ + newlen = XFS_FSB_TO_B(mp, + uirec.br_startoff + uirec.br_blockcount); + newlen = min_t(xfs_off_t, newlen, new_isize); + if (newlen > i_size_read(VFS_I(ip))) { + trace_xfs_reflink_update_inode_size(ip, newlen); + i_size_write(VFS_I(ip), newlen); + ip->i_d.di_size = newlen; + xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); + } + +next_extent: + /* Process all the deferred stuff. */ + error = xfs_defer_finish(&tp, &dfops, ip); + if (error) + goto out_defer; + } + + error = xfs_trans_commit(tp); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + if (error) + goto out; + return 0; + +out_defer: + xfs_defer_cancel(&dfops); +out_cancel: + xfs_trans_cancel(tp); + xfs_iunlock(ip, XFS_ILOCK_EXCL); +out: + trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_); + return error; +} + +/* + * Iteratively remap one file's extents (and holes) to another's. + */ +STATIC int +xfs_reflink_remap_blocks( + struct xfs_inode *src, + xfs_fileoff_t srcoff, + struct xfs_inode *dest, + xfs_fileoff_t destoff, + xfs_filblks_t len, + xfs_off_t new_isize) +{ + struct xfs_bmbt_irec imap; + int nimaps; + int error = 0; + xfs_filblks_t range_len; + + /* drange = (destoff, destoff + len); srange = (srcoff, srcoff + len) */ + while (len) { + trace_xfs_reflink_remap_blocks_loop(src, srcoff, len, + dest, destoff); + /* Read extent from the source file */ + nimaps = 1; + xfs_ilock(src, XFS_ILOCK_EXCL); + error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0); + xfs_iunlock(src, XFS_ILOCK_EXCL); + if (error) + goto err; + ASSERT(nimaps == 1); + + trace_xfs_reflink_remap_imap(src, srcoff, len, XFS_IO_OVERWRITE, + &imap); + + /* Translate imap into the destination file. */ + range_len = imap.br_startoff + imap.br_blockcount - srcoff; + imap.br_startoff += destoff - srcoff; + + /* Clear dest from destoff to the end of imap and map it in. */ + error = xfs_reflink_remap_extent(dest, &imap, destoff, + new_isize); + if (error) + goto err; + + if (fatal_signal_pending(current)) { + error = -EINTR; + goto err; + } + + /* Advance drange/srange */ + srcoff += range_len; + destoff += range_len; + len -= range_len; + } + + return 0; + +err: + trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_); + return error; +} + +/* + * Read a page's worth of file data into the page cache. Return the page + * locked. + */ +static struct page * +xfs_get_page( + struct inode *inode, + xfs_off_t offset) +{ + struct address_space *mapping; + struct page *page; + pgoff_t n; + + n = offset >> PAGE_SHIFT; + mapping = inode->i_mapping; + page = read_mapping_page(mapping, n, NULL); + if (IS_ERR(page)) + return page; + if (!PageUptodate(page)) { + put_page(page); + return ERR_PTR(-EIO); + } + lock_page(page); + return page; +} + +/* + * Compare extents of two files to see if they are the same. + */ +static int +xfs_compare_extents( + struct inode *src, + xfs_off_t srcoff, + struct inode *dest, + xfs_off_t destoff, + xfs_off_t len, + bool *is_same) +{ + xfs_off_t src_poff; + xfs_off_t dest_poff; + void *src_addr; + void *dest_addr; + struct page *src_page; + struct page *dest_page; + xfs_off_t cmp_len; + bool same; + int error; + + error = -EINVAL; + same = true; + while (len) { + src_poff = srcoff & (PAGE_SIZE - 1); + dest_poff = destoff & (PAGE_SIZE - 1); + cmp_len = min(PAGE_SIZE - src_poff, + PAGE_SIZE - dest_poff); + cmp_len = min(cmp_len, len); + ASSERT(cmp_len > 0); + + trace_xfs_reflink_compare_extents(XFS_I(src), srcoff, cmp_len, + XFS_I(dest), destoff); + + src_page = xfs_get_page(src, srcoff); + if (IS_ERR(src_page)) { + error = PTR_ERR(src_page); + goto out_error; + } + dest_page = xfs_get_page(dest, destoff); + if (IS_ERR(dest_page)) { + error = PTR_ERR(dest_page); + unlock_page(src_page); + put_page(src_page); + goto out_error; + } + src_addr = kmap_atomic(src_page); + dest_addr = kmap_atomic(dest_page); + + flush_dcache_page(src_page); + flush_dcache_page(dest_page); + + if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len)) + same = false; + + kunmap_atomic(dest_addr); + kunmap_atomic(src_addr); + unlock_page(dest_page); + unlock_page(src_page); + put_page(dest_page); + put_page(src_page); + + if (!same) + break; + + srcoff += cmp_len; + destoff += cmp_len; + len -= cmp_len; + } + + *is_same = same; + return 0; + +out_error: + trace_xfs_reflink_compare_extents_error(XFS_I(dest), error, _RET_IP_); + return error; +} + +/* + * Link a range of blocks from one file to another. + */ +int +xfs_reflink_remap_range( + struct xfs_inode *src, + xfs_off_t srcoff, + struct xfs_inode *dest, + xfs_off_t destoff, + xfs_off_t len, + unsigned int flags) +{ + struct xfs_mount *mp = src->i_mount; + xfs_fileoff_t sfsbno, dfsbno; + xfs_filblks_t fsblen; + int error; + xfs_extlen_t cowextsize; + bool is_same; + + if (!xfs_sb_version_hasreflink(&mp->m_sb)) + return -EOPNOTSUPP; + + if (XFS_FORCED_SHUTDOWN(mp)) + return -EIO; + + /* Don't reflink realtime inodes */ + if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest)) + return -EINVAL; + + if (flags & ~XFS_REFLINK_ALL) + return -EINVAL; + + trace_xfs_reflink_remap_range(src, srcoff, len, dest, destoff); + + /* Lock both files against IO */ + if (src->i_ino == dest->i_ino) { + xfs_ilock(src, XFS_IOLOCK_EXCL); + xfs_ilock(src, XFS_MMAPLOCK_EXCL); + } else { + xfs_lock_two_inodes(src, dest, XFS_IOLOCK_EXCL); + xfs_lock_two_inodes(src, dest, XFS_MMAPLOCK_EXCL); + } + + /* + * Check that the extents are the same. + */ + if (flags & XFS_REFLINK_DEDUPE) { + is_same = false; + error = xfs_compare_extents(VFS_I(src), srcoff, VFS_I(dest), + destoff, len, &is_same); + if (error) + goto out_error; + if (!is_same) { + error = -EBADE; + goto out_error; + } + } + + error = xfs_reflink_set_inode_flag(src, dest); + if (error) + goto out_error; + + /* + * Invalidate the page cache so that we can clear any CoW mappings + * in the destination file. + */ + truncate_inode_pages_range(&VFS_I(dest)->i_data, destoff, + PAGE_ALIGN(destoff + len) - 1); + + dfsbno = XFS_B_TO_FSBT(mp, destoff); + sfsbno = XFS_B_TO_FSBT(mp, srcoff); + fsblen = XFS_B_TO_FSB(mp, len); + error = xfs_reflink_remap_blocks(src, sfsbno, dest, dfsbno, fsblen, + destoff + len); + if (error) + goto out_error; + + /* + * Carry the cowextsize hint from src to dest if we're sharing the + * entire source file to the entire destination file, the source file + * has a cowextsize hint, and the destination file does not. + */ + cowextsize = 0; + if (srcoff == 0 && len == i_size_read(VFS_I(src)) && + (src->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE) && + destoff == 0 && len >= i_size_read(VFS_I(dest)) && + !(dest->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE)) + cowextsize = src->i_d.di_cowextsize; + + error = xfs_reflink_update_dest(dest, destoff + len, cowextsize); + if (error) + goto out_error; + +out_error: + xfs_iunlock(src, XFS_MMAPLOCK_EXCL); + xfs_iunlock(src, XFS_IOLOCK_EXCL); + if (src->i_ino != dest->i_ino) { + xfs_iunlock(dest, XFS_MMAPLOCK_EXCL); + xfs_iunlock(dest, XFS_IOLOCK_EXCL); + } + if (error) + trace_xfs_reflink_remap_range_error(dest, error, _RET_IP_); + return error; +} + +/* + * The user wants to preemptively CoW all shared blocks in this file, + * which enables us to turn off the reflink flag. Iterate all + * extents which are not prealloc/delalloc to see which ranges are + * mentioned in the refcount tree, then read those blocks into the + * pagecache, dirty them, fsync them back out, and then we can update + * the inode flag. What happens if we run out of memory? :) + */ +STATIC int +xfs_reflink_dirty_extents( + struct xfs_inode *ip, + xfs_fileoff_t fbno, + xfs_filblks_t end, + xfs_off_t isize) +{ + struct xfs_mount *mp = ip->i_mount; + xfs_agnumber_t agno; + xfs_agblock_t agbno; + xfs_extlen_t aglen; + xfs_agblock_t rbno; + xfs_extlen_t rlen; + xfs_off_t fpos; + xfs_off_t flen; + struct xfs_bmbt_irec map[2]; + int nmaps; + int error = 0; + + while (end - fbno > 0) { + nmaps = 1; + /* + * Look for extents in the file. Skip holes, delalloc, or + * unwritten extents; they can't be reflinked. + */ + error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0); + if (error) + goto out; + if (nmaps == 0) + break; + if (map[0].br_startblock == HOLESTARTBLOCK || + map[0].br_startblock == DELAYSTARTBLOCK || + ISUNWRITTEN(&map[0])) + goto next; + + map[1] = map[0]; + while (map[1].br_blockcount) { + agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock); + agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock); + aglen = map[1].br_blockcount; + + error = xfs_reflink_find_shared(mp, agno, agbno, aglen, + &rbno, &rlen, true); + if (error) + goto out; + if (rbno == NULLAGBLOCK) + break; + + /* Dirty the pages */ + xfs_iunlock(ip, XFS_ILOCK_EXCL); + fpos = XFS_FSB_TO_B(mp, map[1].br_startoff + + (rbno - agbno)); + flen = XFS_FSB_TO_B(mp, rlen); + if (fpos + flen > isize) + flen = isize - fpos; + error = iomap_file_dirty(VFS_I(ip), fpos, flen, + &xfs_iomap_ops); + xfs_ilock(ip, XFS_ILOCK_EXCL); + if (error) + goto out; + + map[1].br_blockcount -= (rbno - agbno + rlen); + map[1].br_startoff += (rbno - agbno + rlen); + map[1].br_startblock += (rbno - agbno + rlen); + } + +next: + fbno = map[0].br_startoff + map[0].br_blockcount; + } +out: + return error; +} + +/* Clear the inode reflink flag if there are no shared extents. */ +int +xfs_reflink_clear_inode_flag( + struct xfs_inode *ip, + struct xfs_trans **tpp) +{ + struct xfs_mount *mp = ip->i_mount; + xfs_fileoff_t fbno; + xfs_filblks_t end; + xfs_agnumber_t agno; + xfs_agblock_t agbno; + xfs_extlen_t aglen; + xfs_agblock_t rbno; + xfs_extlen_t rlen; + struct xfs_bmbt_irec map; + int nmaps; + int error = 0; + + ASSERT(xfs_is_reflink_inode(ip)); + + fbno = 0; + end = XFS_B_TO_FSB(mp, i_size_read(VFS_I(ip))); + while (end - fbno > 0) { + nmaps = 1; + /* + * Look for extents in the file. Skip holes, delalloc, or + * unwritten extents; they can't be reflinked. + */ + error = xfs_bmapi_read(ip, fbno, end - fbno, &map, &nmaps, 0); + if (error) + return error; + if (nmaps == 0) + break; + if (map.br_startblock == HOLESTARTBLOCK || + map.br_startblock == DELAYSTARTBLOCK || + ISUNWRITTEN(&map)) + goto next; + + agno = XFS_FSB_TO_AGNO(mp, map.br_startblock); + agbno = XFS_FSB_TO_AGBNO(mp, map.br_startblock); + aglen = map.br_blockcount; + + error = xfs_reflink_find_shared(mp, agno, agbno, aglen, + &rbno, &rlen, false); + if (error) + return error; + /* Is there still a shared block here? */ + if (rbno != NULLAGBLOCK) + return 0; +next: + fbno = map.br_startoff + map.br_blockcount; + } + + /* + * We didn't find any shared blocks so turn off the reflink flag. + * First, get rid of any leftover CoW mappings. + */ + error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF); + if (error) + return error; + + /* Clear the inode flag. */ + trace_xfs_reflink_unset_inode_flag(ip); + ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK; + xfs_inode_clear_cowblocks_tag(ip); + xfs_trans_ijoin(*tpp, ip, 0); + xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE); + + return error; +} + +/* + * Clear the inode reflink flag if there are no shared extents and the size + * hasn't changed. + */ +STATIC int +xfs_reflink_try_clear_inode_flag( + struct xfs_inode *ip) +{ + struct xfs_mount *mp = ip->i_mount; + struct xfs_trans *tp; + int error = 0; + + /* Start a rolling transaction to remove the mappings */ + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp); + if (error) + return error; + + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, ip, 0); + + error = xfs_reflink_clear_inode_flag(ip, &tp); + if (error) + goto cancel; + + error = xfs_trans_commit(tp); + if (error) + goto out; + + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return 0; +cancel: + xfs_trans_cancel(tp); +out: + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return error; +} + +/* + * Pre-COW all shared blocks within a given byte range of a file and turn off + * the reflink flag if we unshare all of the file's blocks. + */ +int +xfs_reflink_unshare( + struct xfs_inode *ip, + xfs_off_t offset, + xfs_off_t len) +{ + struct xfs_mount *mp = ip->i_mount; + xfs_fileoff_t fbno; + xfs_filblks_t end; + xfs_off_t isize; + int error; + + if (!xfs_is_reflink_inode(ip)) + return 0; + + trace_xfs_reflink_unshare(ip, offset, len); + + inode_dio_wait(VFS_I(ip)); + + /* Try to CoW the selected ranges */ + xfs_ilock(ip, XFS_ILOCK_EXCL); + fbno = XFS_B_TO_FSBT(mp, offset); + isize = i_size_read(VFS_I(ip)); + end = XFS_B_TO_FSB(mp, offset + len); + error = xfs_reflink_dirty_extents(ip, fbno, end, isize); + if (error) + goto out_unlock; + xfs_iunlock(ip, XFS_ILOCK_EXCL); + + /* Wait for the IO to finish */ + error = filemap_write_and_wait(VFS_I(ip)->i_mapping); + if (error) + goto out; + + /* Turn off the reflink flag if possible. */ + error = xfs_reflink_try_clear_inode_flag(ip); + if (error) + goto out; + + return 0; + +out_unlock: + xfs_iunlock(ip, XFS_ILOCK_EXCL); +out: + trace_xfs_reflink_unshare_error(ip, error, _RET_IP_); + return error; +} + +/* + * Does this inode have any real CoW reservations? + */ +bool +xfs_reflink_has_real_cow_blocks( + struct xfs_inode *ip) +{ + struct xfs_bmbt_irec irec; + struct xfs_ifork *ifp; + struct xfs_bmbt_rec_host *gotp; + xfs_extnum_t idx; + + if (!xfs_is_reflink_inode(ip)) + return false; + + /* Go find the old extent in the CoW fork. */ + ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); + gotp = xfs_iext_bno_to_ext(ifp, 0, &idx); + while (gotp) { + xfs_bmbt_get_all(gotp, &irec); + + if (!isnullstartblock(irec.br_startblock)) + return true; + + /* Roll on... */ + idx++; + if (idx >= ifp->if_bytes / sizeof(xfs_bmbt_rec_t)) + break; + gotp = xfs_iext_get_ext(ifp, idx); + } + + return false; +} |