diff options
Diffstat (limited to 'fs/xfs/xfs_reflink.c')
| -rw-r--r-- | fs/xfs/xfs_reflink.c | 1743 |
1 files changed, 1743 insertions, 0 deletions
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c new file mode 100644 index 000000000..0b159a79a --- /dev/null +++ b/fs/xfs/xfs_reflink.c @@ -0,0 +1,1743 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (C) 2016 Oracle. All Rights Reserved. + * Author: Darrick J. Wong <darrick.wong@oracle.com> + */ +#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_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. + * + * As an optimization, the CoW extent size hint (cowextsz) creates + * outsized aligned delalloc reservations in the hope of landing out of + * order nearby CoW writes in a single extent on disk, thereby reducing + * fragmentation and improving future performance. + * + * D: --RRRRRRSSSRRRRRRRR--- (data fork) + * C: ------DDDDDDD--------- (CoW fork) + * + * When dirty pages are being written out (typically in writepage), the + * delalloc reservations are converted into unwritten mappings by + * allocating blocks and replacing the delalloc mapping with real ones. + * A delalloc mapping can be replaced by several unwritten ones if the + * free space is fragmented. + * + * D: --RRRRRRSSSRRRRRRRR--- + * C: ------UUUUUUU--------- + * + * 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. + * + * Just prior to submitting the actual disk write requests, we convert + * the extents representing the range of the file actually being written + * (as opposed to extra pieces created for the cowextsize hint) to real + * extents. This will become important in the next step: + * + * D: --RRRRRRSSSRRRRRRRR--- + * C: ------UUrrUUU--------- + * + * 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. Because of + * the presence of the cowextsize hint, however, we must be careful + * only to remap the blocks that we've actually written out -- we must + * never remap delalloc reservations nor CoW staging blocks that have + * yet to be written. This corresponds exactly to the real extents in + * the CoW fork: + * + * D: --RRRRRRrrSRRRRRRRR--- + * C: ------UU--UUU--------- + * + * 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, + struct xfs_trans *tp, + 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, tp, agno, 0, &agbp); + if (error) + return error; + if (!agbp) + return -ENOMEM; + + cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno); + + error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen, + find_end_of_shared); + + xfs_btree_del_cursor(cur, error); + + xfs_trans_brelse(tp, 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) || !xfs_bmap_is_real_extent(irec)) { + *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, NULL, 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; + } +} + +/* + * 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; + struct xfs_iext_cursor icur; + + /* + * 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, &icur, &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, false); + if (error) + return error; + + error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff, + imap->br_blockcount, 0, &got, &icur, eof); + if (error == -ENOSPC || error == -EDQUOT) + trace_xfs_reflink_cow_enospc(ip, imap); + if (error) + return error; + + xfs_trim_extent(imap, got.br_startoff, got.br_blockcount); + trace_xfs_reflink_cow_alloc(ip, &got); + return 0; +} + +/* Convert part of an unwritten CoW extent to a real one. */ +STATIC int +xfs_reflink_convert_cow_extent( + struct xfs_inode *ip, + struct xfs_bmbt_irec *imap, + xfs_fileoff_t offset_fsb, + xfs_filblks_t count_fsb) +{ + int nimaps = 1; + + if (imap->br_state == XFS_EXT_NORM) + return 0; + + xfs_trim_extent(imap, offset_fsb, count_fsb); + trace_xfs_reflink_convert_cow(ip, imap); + if (imap->br_blockcount == 0) + return 0; + return xfs_bmapi_write(NULL, ip, imap->br_startoff, imap->br_blockcount, + XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT, 0, imap, + &nimaps); +} + +/* Convert all of the unwritten CoW extents in a file's range to real ones. */ +int +xfs_reflink_convert_cow( + 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); + xfs_filblks_t count_fsb = end_fsb - offset_fsb; + struct xfs_bmbt_irec imap; + int nimaps = 1, error = 0; + + ASSERT(count != 0); + + xfs_ilock(ip, XFS_ILOCK_EXCL); + error = xfs_bmapi_write(NULL, ip, offset_fsb, count_fsb, + XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT | + XFS_BMAPI_CONVERT_ONLY, 0, &imap, &nimaps); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return error; +} + +/* + * Find the extent that maps the given range in the COW fork. Even if the extent + * is not shared we might have a preallocation for it in the COW fork. If so we + * use it that rather than trigger a new allocation. + */ +static int +xfs_find_trim_cow_extent( + struct xfs_inode *ip, + struct xfs_bmbt_irec *imap, + bool *shared, + bool *found) +{ + xfs_fileoff_t offset_fsb = imap->br_startoff; + xfs_filblks_t count_fsb = imap->br_blockcount; + struct xfs_iext_cursor icur; + struct xfs_bmbt_irec got; + bool trimmed; + + *found = false; + + /* + * If we don't find an overlapping extent, trim the range we need to + * allocate to fit the hole we found. + */ + if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got) || + got.br_startoff > offset_fsb) + return xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed); + + *shared = true; + if (isnullstartblock(got.br_startblock)) { + xfs_trim_extent(imap, got.br_startoff, got.br_blockcount); + return 0; + } + + /* real extent found - no need to allocate */ + xfs_trim_extent(&got, offset_fsb, count_fsb); + *imap = got; + *found = true; + return 0; +} + +/* 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_trans *tp; + int nimaps, error = 0; + bool found; + xfs_filblks_t resaligned; + xfs_extlen_t resblks = 0; + + ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL)); + ASSERT(xfs_is_reflink_inode(ip)); + + error = xfs_find_trim_cow_extent(ip, imap, shared, &found); + if (error || !*shared) + return error; + if (found) + goto convert; + + 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, false); + if (error) + goto out_trans_cancel; + + /* + * Check for an overlapping extent again now that we dropped the ilock. + */ + error = xfs_find_trim_cow_extent(ip, imap, shared, &found); + if (error || !*shared) + goto out_trans_cancel; + if (found) { + xfs_trans_cancel(tp); + goto convert; + } + + error = xfs_trans_reserve_quota_nblks(tp, ip, resblks, 0, + XFS_QMOPT_RES_REGBLKS); + if (error) + goto out_trans_cancel; + + xfs_trans_ijoin(tp, ip, 0); + + /* Allocate the entire reservation as unwritten blocks. */ + nimaps = 1; + error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount, + XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, + resblks, imap, &nimaps); + if (error) + goto out_unreserve; + + xfs_inode_set_cowblocks_tag(ip); + error = xfs_trans_commit(tp); + if (error) + return error; + + /* + * Allocation succeeded but the requested range was not even partially + * satisfied? Bail out! + */ + if (nimaps == 0) + return -ENOSPC; +convert: + return xfs_reflink_convert_cow_extent(ip, imap, offset_fsb, count_fsb); + +out_unreserve: + xfs_trans_unreserve_quota_nblks(tp, ip, (long)resblks, 0, + XFS_QMOPT_RES_REGBLKS); +out_trans_cancel: + xfs_trans_cancel(tp); + return error; +} + +/* + * Cancel CoW reservations for some block range of an inode. + * + * If cancel_real is true this function cancels all COW fork extents for the + * inode; if cancel_real is false, real extents are not cleared. + * + * Caller must have already joined the inode to the current transaction. The + * inode will be joined to the transaction returned to the caller. + */ +int +xfs_reflink_cancel_cow_blocks( + struct xfs_inode *ip, + struct xfs_trans **tpp, + xfs_fileoff_t offset_fsb, + xfs_fileoff_t end_fsb, + bool cancel_real) +{ + struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); + struct xfs_bmbt_irec got, del; + struct xfs_iext_cursor icur; + int error = 0; + + if (!xfs_inode_has_cow_data(ip)) + return 0; + if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got)) + return 0; + + /* Walk backwards until we're out of the I/O range... */ + while (got.br_startoff + got.br_blockcount > offset_fsb) { + del = got; + xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb); + + /* Extent delete may have bumped ext forward */ + if (!del.br_blockcount) { + xfs_iext_prev(ifp, &icur); + goto next_extent; + } + + trace_xfs_reflink_cancel_cow(ip, &del); + + if (isnullstartblock(del.br_startblock)) { + error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK, + &icur, &got, &del); + if (error) + break; + } else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) { + ASSERT((*tpp)->t_firstblock == NULLFSBLOCK); + + /* Free the CoW orphan record. */ + error = xfs_refcount_free_cow_extent(*tpp, + del.br_startblock, del.br_blockcount); + if (error) + break; + + xfs_bmap_add_free(*tpp, del.br_startblock, + del.br_blockcount, NULL); + + /* Roll the transaction */ + error = xfs_defer_finish(tpp); + if (error) + break; + + /* Remove the mapping from the CoW fork. */ + xfs_bmap_del_extent_cow(ip, &icur, &got, &del); + + /* Remove the quota reservation */ + error = xfs_trans_reserve_quota_nblks(NULL, ip, + -(long)del.br_blockcount, 0, + XFS_QMOPT_RES_REGBLKS); + if (error) + break; + } else { + /* Didn't do anything, push cursor back. */ + xfs_iext_prev(ifp, &icur); + } +next_extent: + if (!xfs_iext_get_extent(ifp, &icur, &got)) + break; + } + + /* clear tag if cow fork is emptied */ + if (!ifp->if_bytes) + xfs_inode_clear_cowblocks_tag(ip); + return error; +} + +/* + * Cancel CoW reservations for some byte range of an inode. + * + * If cancel_real is true this function cancels all COW fork extents for the + * inode; if cancel_real is false, real extents are not cleared. + */ +int +xfs_reflink_cancel_cow_range( + struct xfs_inode *ip, + xfs_off_t offset, + xfs_off_t count, + bool cancel_real) +{ + 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, XFS_TRANS_NOFS, &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, + cancel_real); + 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_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); + struct xfs_bmbt_irec got, del; + struct xfs_trans *tp; + xfs_fileoff_t offset_fsb; + xfs_fileoff_t end_fsb; + int error; + unsigned int resblks; + xfs_filblks_t rlen; + struct xfs_iext_cursor icur; + + trace_xfs_reflink_end_cow(ip, offset, count); + + /* No COW extents? That's easy! */ + if (ifp->if_bytes == 0) + return 0; + + offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset); + end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count); + + /* + * Start a rolling transaction to switch the mappings. We're + * unlikely ever to have to remap 16T worth of single-block + * extents, so just cap the worst case extent count to 2^32-1. + * Stick a warning in just in case, and avoid 64-bit division. + */ + BUILD_BUG_ON(MAX_RW_COUNT > UINT_MAX); + if (end_fsb - offset_fsb > UINT_MAX) { + error = -EFSCORRUPTED; + xfs_force_shutdown(ip->i_mount, SHUTDOWN_CORRUPT_INCORE); + ASSERT(0); + goto out; + } + resblks = XFS_NEXTENTADD_SPACE_RES(ip->i_mount, + (unsigned int)(end_fsb - offset_fsb), + XFS_DATA_FORK); + error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write, + resblks, 0, XFS_TRANS_RESERVE | XFS_TRANS_NOFS, &tp); + if (error) + goto out; + + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, ip, 0); + + /* + * In case of racing, overlapping AIO writes no COW extents might be + * left by the time I/O completes for the loser of the race. In that + * case we are done. + */ + if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got)) + goto out_cancel; + + /* Walk backwards until we're out of the I/O range... */ + while (got.br_startoff + got.br_blockcount > offset_fsb) { + del = got; + xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb); + + /* Extent delete may have bumped ext forward */ + if (!del.br_blockcount) + goto prev_extent; + + /* + * Only remap real extent that contain data. With AIO + * speculatively preallocations can leak into the range we + * are called upon, and we need to skip them. + */ + if (!xfs_bmap_is_real_extent(&got)) + goto prev_extent; + + /* Unmap the old blocks in the data fork. */ + ASSERT(tp->t_firstblock == NULLFSBLOCK); + rlen = del.br_blockcount; + error = __xfs_bunmapi(tp, ip, del.br_startoff, &rlen, 0, 1); + if (error) + goto out_cancel; + + /* Trim the extent to whatever got unmapped. */ + if (rlen) { + xfs_trim_extent(&del, del.br_startoff + rlen, + del.br_blockcount - rlen); + } + trace_xfs_reflink_cow_remap(ip, &del); + + /* Free the CoW orphan record. */ + error = xfs_refcount_free_cow_extent(tp, del.br_startblock, + del.br_blockcount); + if (error) + goto out_cancel; + + /* Map the new blocks into the data fork. */ + error = xfs_bmap_map_extent(tp, ip, &del); + if (error) + goto out_cancel; + + /* Charge this new data fork mapping to the on-disk quota. */ + xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT, + (long)del.br_blockcount); + + /* Remove the mapping from the CoW fork. */ + xfs_bmap_del_extent_cow(ip, &icur, &got, &del); + + error = xfs_defer_finish(&tp); + if (error) + goto out_cancel; + if (!xfs_iext_get_extent(ifp, &icur, &got)) + break; + continue; +prev_extent: + if (!xfs_iext_prev_extent(ifp, &icur, &got)) + break; + } + + error = xfs_trans_commit(tp); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + if (error) + goto out; + return 0; + +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, XFS_ILOCK_EXCL, 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, + bool is_dedupe) +{ + struct xfs_mount *mp = dest->i_mount; + struct xfs_trans *tp; + int error; + + if (is_dedupe && 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; + } + + if (!is_dedupe) { + xfs_trans_ichgtime(tp, dest, + XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG); + } + 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_RMAPBT) || + 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; + bool real_extent = xfs_bmap_is_real_extent(irec); + struct xfs_trans *tp; + unsigned int resblks; + struct xfs_bmbt_irec uirec; + xfs_filblks_t rlen; + xfs_filblks_t unmap_len; + xfs_off_t newlen; + int64_t qres; + int error; + + unmap_len = irec->br_startoff + irec->br_blockcount - destoff; + trace_xfs_reflink_punch_range(ip, destoff, unmap_len); + + /* 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); + + /* + * Reserve quota for this operation. We don't know if the first unmap + * in the dest file will cause a bmap btree split, so we always reserve + * at least enough blocks for that split. If the extent being mapped + * in is written, we need to reserve quota for that too. + */ + qres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK); + if (real_extent) + qres += irec->br_blockcount; + error = xfs_trans_reserve_quota_nblks(tp, ip, qres, 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) { + ASSERT(tp->t_firstblock == NULLFSBLOCK); + error = __xfs_bunmapi(tp, ip, destoff, &rlen, 0, 1); + if (error) + goto out_cancel; + + /* + * 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; + uirec.br_state = irec->br_state; + 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(tp, &uirec); + if (error) + goto out_cancel; + + /* Map the new blocks into the data fork. */ + error = xfs_bmap_map_extent(tp, ip, &uirec); + if (error) + goto out_cancel; + + /* 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); + if (error) + goto out_cancel; + } + + error = xfs_trans_commit(tp); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + if (error) + goto out; + return 0; + +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) { + uint lock_mode; + + trace_xfs_reflink_remap_blocks_loop(src, srcoff, len, + dest, destoff); + + /* Read extent from the source file */ + nimaps = 1; + lock_mode = xfs_ilock_data_map_shared(src); + error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0); + xfs_iunlock(src, lock_mode); + 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; +} + +/* + * Grab the exclusive iolock for a data copy from src to dest, making + * sure to abide vfs locking order (lowest pointer value goes first) and + * breaking the pnfs layout leases on dest before proceeding. The loop + * is needed because we cannot call the blocking break_layout() with the + * src iolock held, and therefore have to back out both locks. + */ +static int +xfs_iolock_two_inodes_and_break_layout( + struct inode *src, + struct inode *dest) +{ + int error; + +retry: + if (src < dest) { + inode_lock_shared(src); + inode_lock_nested(dest, I_MUTEX_NONDIR2); + } else { + /* src >= dest */ + inode_lock(dest); + } + + error = break_layout(dest, false); + if (error == -EWOULDBLOCK) { + inode_unlock(dest); + if (src < dest) + inode_unlock_shared(src); + error = break_layout(dest, true); + if (error) + return error; + goto retry; + } + if (error) { + inode_unlock(dest); + if (src < dest) + inode_unlock_shared(src); + return error; + } + if (src > dest) + inode_lock_shared_nested(src, I_MUTEX_NONDIR2); + return 0; +} + +/* Unlock both inodes after they've been prepped for a range clone. */ +STATIC void +xfs_reflink_remap_unlock( + struct file *file_in, + struct file *file_out) +{ + struct inode *inode_in = file_inode(file_in); + struct xfs_inode *src = XFS_I(inode_in); + struct inode *inode_out = file_inode(file_out); + struct xfs_inode *dest = XFS_I(inode_out); + bool same_inode = (inode_in == inode_out); + + xfs_iunlock(dest, XFS_MMAPLOCK_EXCL); + if (!same_inode) + xfs_iunlock(src, XFS_MMAPLOCK_SHARED); + inode_unlock(inode_out); + if (!same_inode) + inode_unlock_shared(inode_in); +} + +/* + * If we're reflinking to a point past the destination file's EOF, we must + * zero any speculative post-EOF preallocations that sit between the old EOF + * and the destination file offset. + */ +static int +xfs_reflink_zero_posteof( + struct xfs_inode *ip, + loff_t pos) +{ + loff_t isize = i_size_read(VFS_I(ip)); + + if (pos <= isize) + return 0; + + trace_xfs_zero_eof(ip, isize, pos - isize); + return iomap_zero_range(VFS_I(ip), isize, pos - isize, NULL, + &xfs_iomap_ops); +} + +/* + * Prepare two files for range cloning. Upon a successful return both inodes + * will have the iolock and mmaplock held, the page cache of the out file will + * be truncated, and any leases on the out file will have been broken. This + * function borrows heavily from xfs_file_aio_write_checks. + * + * The VFS allows partial EOF blocks to "match" for dedupe even though it hasn't + * checked that the bytes beyond EOF physically match. Hence we cannot use the + * EOF block in the source dedupe range because it's not a complete block match, + * hence can introduce a corruption into the file that has it's block replaced. + * + * In similar fashion, the VFS file cloning also allows partial EOF blocks to be + * "block aligned" for the purposes of cloning entire files. However, if the + * source file range includes the EOF block and it lands within the existing EOF + * of the destination file, then we can expose stale data from beyond the source + * file EOF in the destination file. + * + * XFS doesn't support partial block sharing, so in both cases we have check + * these cases ourselves. For dedupe, we can simply round the length to dedupe + * down to the previous whole block and ignore the partial EOF block. While this + * means we can't dedupe the last block of a file, this is an acceptible + * tradeoff for simplicity on implementation. + * + * For cloning, we want to share the partial EOF block if it is also the new EOF + * block of the destination file. If the partial EOF block lies inside the + * existing destination EOF, then we have to abort the clone to avoid exposing + * stale data in the destination file. Hence we reject these clone attempts with + * -EINVAL in this case. + */ +STATIC int +xfs_reflink_remap_prep( + struct file *file_in, + loff_t pos_in, + struct file *file_out, + loff_t pos_out, + u64 *len, + bool is_dedupe) +{ + struct inode *inode_in = file_inode(file_in); + struct xfs_inode *src = XFS_I(inode_in); + struct inode *inode_out = file_inode(file_out); + struct xfs_inode *dest = XFS_I(inode_out); + bool same_inode = (inode_in == inode_out); + u64 blkmask = i_blocksize(inode_in) - 1; + ssize_t ret; + + /* Lock both files against IO */ + ret = xfs_iolock_two_inodes_and_break_layout(inode_in, inode_out); + if (ret) + return ret; + if (same_inode) + xfs_ilock(src, XFS_MMAPLOCK_EXCL); + else + xfs_lock_two_inodes(src, XFS_MMAPLOCK_SHARED, dest, + XFS_MMAPLOCK_EXCL); + + /* Check file eligibility and prepare for block sharing. */ + ret = -EINVAL; + /* Don't reflink realtime inodes */ + if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest)) + goto out_unlock; + + /* Don't share DAX file data for now. */ + if (IS_DAX(inode_in) || IS_DAX(inode_out)) + goto out_unlock; + + ret = vfs_clone_file_prep_inodes(inode_in, pos_in, inode_out, pos_out, + len, is_dedupe); + if (ret <= 0) + goto out_unlock; + + /* + * If the dedupe data matches, chop off the partial EOF block + * from the source file so we don't try to dedupe the partial + * EOF block. + */ + if (is_dedupe) { + *len &= ~blkmask; + } else if (*len & blkmask) { + /* + * The user is attempting to share a partial EOF block, + * if it's inside the destination EOF then reject it. + */ + if (pos_out + *len < i_size_read(inode_out)) { + ret = -EINVAL; + goto out_unlock; + } + } + + /* Attach dquots to dest inode before changing block map */ + ret = xfs_qm_dqattach(dest); + if (ret) + goto out_unlock; + + /* + * Zero existing post-eof speculative preallocations in the destination + * file. + */ + ret = xfs_reflink_zero_posteof(dest, pos_out); + if (ret) + goto out_unlock; + + /* Set flags and remap blocks. */ + ret = xfs_reflink_set_inode_flag(src, dest); + if (ret) + goto out_unlock; + + /* + * If pos_out > EOF, we may have dirtied blocks between EOF and + * pos_out. In that case, we need to extend the flush and unmap to cover + * from EOF to the end of the copy length. + */ + if (pos_out > XFS_ISIZE(dest)) { + loff_t flen = *len + (pos_out - XFS_ISIZE(dest)); + ret = xfs_flush_unmap_range(dest, XFS_ISIZE(dest), flen); + } else { + ret = xfs_flush_unmap_range(dest, pos_out, *len); + } + if (ret) + goto out_unlock; + + /* If we're altering the file contents... */ + if (!is_dedupe) { + /* + * ...update the timestamps (which will grab the ilock again + * from xfs_fs_dirty_inode, so we have to call it before we + * take the ilock). + */ + if (!(file_out->f_mode & FMODE_NOCMTIME)) { + ret = file_update_time(file_out); + if (ret) + goto out_unlock; + } + + /* + * ...clear the security bits if the process is not being run + * by root. This keeps people from modifying setuid and setgid + * binaries. + */ + ret = file_remove_privs(file_out); + if (ret) + goto out_unlock; + } + + return 1; +out_unlock: + xfs_reflink_remap_unlock(file_in, file_out); + return ret; +} + +/* + * Link a range of blocks from one file to another. + */ +int +xfs_reflink_remap_range( + struct file *file_in, + loff_t pos_in, + struct file *file_out, + loff_t pos_out, + u64 len, + bool is_dedupe) +{ + struct inode *inode_in = file_inode(file_in); + struct xfs_inode *src = XFS_I(inode_in); + struct inode *inode_out = file_inode(file_out); + struct xfs_inode *dest = XFS_I(inode_out); + struct xfs_mount *mp = src->i_mount; + xfs_fileoff_t sfsbno, dfsbno; + xfs_filblks_t fsblen; + xfs_extlen_t cowextsize; + ssize_t ret; + + if (!xfs_sb_version_hasreflink(&mp->m_sb)) + return -EOPNOTSUPP; + + if (XFS_FORCED_SHUTDOWN(mp)) + return -EIO; + + /* Prepare and then clone file data. */ + ret = xfs_reflink_remap_prep(file_in, pos_in, file_out, pos_out, + &len, is_dedupe); + if (ret <= 0) + return ret; + + trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out); + + dfsbno = XFS_B_TO_FSBT(mp, pos_out); + sfsbno = XFS_B_TO_FSBT(mp, pos_in); + fsblen = XFS_B_TO_FSB(mp, len); + ret = xfs_reflink_remap_blocks(src, sfsbno, dest, dfsbno, fsblen, + pos_out + len); + if (ret) + goto out_unlock; + + /* + * 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 (pos_in == 0 && len == i_size_read(inode_in) && + (src->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE) && + pos_out == 0 && len >= i_size_read(inode_out) && + !(dest->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE)) + cowextsize = src->i_d.di_cowextsize; + + ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize, + is_dedupe); + +out_unlock: + xfs_reflink_remap_unlock(file_in, file_out); + if (ret) + trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_); + return ret; +} + +/* + * 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 (!xfs_bmap_is_real_extent(&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, NULL, 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; +} + +/* Does this inode need the reflink flag? */ +int +xfs_reflink_inode_has_shared_extents( + struct xfs_trans *tp, + struct xfs_inode *ip, + bool *has_shared) +{ + struct xfs_bmbt_irec got; + struct xfs_mount *mp = ip->i_mount; + struct xfs_ifork *ifp; + xfs_agnumber_t agno; + xfs_agblock_t agbno; + xfs_extlen_t aglen; + xfs_agblock_t rbno; + xfs_extlen_t rlen; + struct xfs_iext_cursor icur; + bool found; + int error; + + ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK); + if (!(ifp->if_flags & XFS_IFEXTENTS)) { + error = xfs_iread_extents(tp, ip, XFS_DATA_FORK); + if (error) + return error; + } + + *has_shared = false; + found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got); + while (found) { + if (isnullstartblock(got.br_startblock) || + got.br_state != XFS_EXT_NORM) + goto next; + agno = XFS_FSB_TO_AGNO(mp, got.br_startblock); + agbno = XFS_FSB_TO_AGBNO(mp, got.br_startblock); + aglen = got.br_blockcount; + + error = xfs_reflink_find_shared(mp, tp, agno, agbno, aglen, + &rbno, &rlen, false); + if (error) + return error; + /* Is there still a shared block here? */ + if (rbno != NULLAGBLOCK) { + *has_shared = true; + return 0; + } +next: + found = xfs_iext_next_extent(ifp, &icur, &got); + } + + return 0; +} + +/* + * Clear the inode reflink flag if there are no shared extents. + * + * The caller is responsible for joining the inode to the transaction passed in. + * The inode will be joined to the transaction that is returned to the caller. + */ +int +xfs_reflink_clear_inode_flag( + struct xfs_inode *ip, + struct xfs_trans **tpp) +{ + bool needs_flag; + int error = 0; + + ASSERT(xfs_is_reflink_inode(ip)); + + error = xfs_reflink_inode_has_shared_extents(*tpp, ip, &needs_flag); + if (error || needs_flag) + return error; + + /* + * 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, true); + 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_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; +} |