v4.19.13 snapshot.
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
new file mode 100644
index 0000000..42ea7ba
--- /dev/null
+++ b/fs/xfs/xfs_reflink.c
@@ -0,0 +1,1724 @@
+// 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;
+
+ 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;
+ 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);
+
+ /* 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) {
+ 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;
+ 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;
+
+ /* Zap any page cache for the destination file's range. */
+ truncate_inode_pages_range(&inode_out->i_data, pos_out,
+ PAGE_ALIGN(pos_out + *len) - 1);
+
+ /* 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;
+}