/* * Copyright (C) 2016 Oracle. All Rights Reserved. * * Author: Darrick J. Wong * * 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; 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[2]; 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[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, false); if (error) return error; /* Is there still a shared block here? */ if (rbno != NULLAGBLOCK) return 0; map[1].br_blockcount -= aglen; map[1].br_startoff += aglen; map[1].br_startblock += aglen; } next: fbno = map[0].br_startoff + map[0].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, xfs_off_t old_isize) { 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); if (old_isize != i_size_read(VFS_I(ip))) goto cancel; 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_FSB(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 we unshared the whole file */ if (offset == 0 && len == isize) { error = xfs_reflink_try_clear_inode_flag(ip, isize); 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; }