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![Dave Chinner](/assets/img/avatar_default.png)
Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
1542 lines
44 KiB
C
1542 lines
44 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2016 Oracle. All Rights Reserved.
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* Author: Darrick J. Wong <darrick.wong@oracle.com>
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*/
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#include "xfs.h"
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#include "xfs_fs.h"
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#include "xfs_shared.h"
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#include "xfs_format.h"
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#include "xfs_log_format.h"
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#include "xfs_trans_resv.h"
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#include "xfs_mount.h"
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#include "xfs_defer.h"
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#include "xfs_inode.h"
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#include "xfs_trans.h"
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#include "xfs_bmap.h"
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#include "xfs_bmap_util.h"
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#include "xfs_trace.h"
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#include "xfs_icache.h"
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#include "xfs_btree.h"
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#include "xfs_refcount_btree.h"
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#include "xfs_refcount.h"
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#include "xfs_bmap_btree.h"
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#include "xfs_trans_space.h"
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#include "xfs_bit.h"
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#include "xfs_alloc.h"
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#include "xfs_quota.h"
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#include "xfs_reflink.h"
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#include "xfs_iomap.h"
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#include "xfs_ag.h"
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#include "xfs_ag_resv.h"
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/*
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* Copy on Write of Shared Blocks
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*
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* XFS must preserve "the usual" file semantics even when two files share
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* the same physical blocks. This means that a write to one file must not
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* alter the blocks in a different file; the way that we'll do that is
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* through the use of a copy-on-write mechanism. At a high level, that
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* means that when we want to write to a shared block, we allocate a new
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* block, write the data to the new block, and if that succeeds we map the
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* new block into the file.
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*
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* XFS provides a "delayed allocation" mechanism that defers the allocation
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* of disk blocks to dirty-but-not-yet-mapped file blocks as long as
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* possible. This reduces fragmentation by enabling the filesystem to ask
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* for bigger chunks less often, which is exactly what we want for CoW.
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*
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* The delalloc mechanism begins when the kernel wants to make a block
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* writable (write_begin or page_mkwrite). If the offset is not mapped, we
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* create a delalloc mapping, which is a regular in-core extent, but without
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* a real startblock. (For delalloc mappings, the startblock encodes both
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* a flag that this is a delalloc mapping, and a worst-case estimate of how
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* many blocks might be required to put the mapping into the BMBT.) delalloc
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* mappings are a reservation against the free space in the filesystem;
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* adjacent mappings can also be combined into fewer larger mappings.
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*
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* As an optimization, the CoW extent size hint (cowextsz) creates
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* outsized aligned delalloc reservations in the hope of landing out of
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* order nearby CoW writes in a single extent on disk, thereby reducing
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* fragmentation and improving future performance.
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*
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* D: --RRRRRRSSSRRRRRRRR--- (data fork)
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* C: ------DDDDDDD--------- (CoW fork)
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*
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* When dirty pages are being written out (typically in writepage), the
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* delalloc reservations are converted into unwritten mappings by
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* allocating blocks and replacing the delalloc mapping with real ones.
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* A delalloc mapping can be replaced by several unwritten ones if the
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* free space is fragmented.
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*
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* D: --RRRRRRSSSRRRRRRRR---
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* C: ------UUUUUUU---------
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*
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* We want to adapt the delalloc mechanism for copy-on-write, since the
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* write paths are similar. The first two steps (creating the reservation
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* and allocating the blocks) are exactly the same as delalloc except that
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* the mappings must be stored in a separate CoW fork because we do not want
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* to disturb the mapping in the data fork until we're sure that the write
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* succeeded. IO completion in this case is the process of removing the old
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* mapping from the data fork and moving the new mapping from the CoW fork to
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* the data fork. This will be discussed shortly.
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*
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* For now, unaligned directio writes will be bounced back to the page cache.
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* Block-aligned directio writes will use the same mechanism as buffered
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* writes.
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*
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* Just prior to submitting the actual disk write requests, we convert
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* the extents representing the range of the file actually being written
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* (as opposed to extra pieces created for the cowextsize hint) to real
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* extents. This will become important in the next step:
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*
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* D: --RRRRRRSSSRRRRRRRR---
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* C: ------UUrrUUU---------
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*
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* CoW remapping must be done after the data block write completes,
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* because we don't want to destroy the old data fork map until we're sure
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* the new block has been written. Since the new mappings are kept in a
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* separate fork, we can simply iterate these mappings to find the ones
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* that cover the file blocks that we just CoW'd. For each extent, simply
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* unmap the corresponding range in the data fork, map the new range into
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* the data fork, and remove the extent from the CoW fork. Because of
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* the presence of the cowextsize hint, however, we must be careful
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* only to remap the blocks that we've actually written out -- we must
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* never remap delalloc reservations nor CoW staging blocks that have
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* yet to be written. This corresponds exactly to the real extents in
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* the CoW fork:
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*
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* D: --RRRRRRrrSRRRRRRRR---
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* C: ------UU--UUU---------
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*
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* Since the remapping operation can be applied to an arbitrary file
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* range, we record the need for the remap step as a flag in the ioend
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* instead of declaring a new IO type. This is required for direct io
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* because we only have ioend for the whole dio, and we have to be able to
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* remember the presence of unwritten blocks and CoW blocks with a single
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* ioend structure. Better yet, the more ground we can cover with one
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* ioend, the better.
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*/
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/*
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* Given an AG extent, find the lowest-numbered run of shared blocks
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* within that range and return the range in fbno/flen. If
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* find_end_of_shared is true, return the longest contiguous extent of
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* shared blocks. If there are no shared extents, fbno and flen will
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* be set to NULLAGBLOCK and 0, respectively.
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*/
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int
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xfs_reflink_find_shared(
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struct xfs_mount *mp,
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struct xfs_trans *tp,
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xfs_agnumber_t agno,
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xfs_agblock_t agbno,
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xfs_extlen_t aglen,
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xfs_agblock_t *fbno,
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xfs_extlen_t *flen,
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bool find_end_of_shared)
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{
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struct xfs_buf *agbp;
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struct xfs_btree_cur *cur;
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int error;
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error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
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if (error)
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return error;
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cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agbp->b_pag);
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error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen,
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find_end_of_shared);
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xfs_btree_del_cursor(cur, error);
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xfs_trans_brelse(tp, agbp);
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return error;
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}
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/*
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* Trim the mapping to the next block where there's a change in the
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* shared/unshared status. More specifically, this means that we
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* find the lowest-numbered extent of shared blocks that coincides with
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* the given block mapping. If the shared extent overlaps the start of
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* the mapping, trim the mapping to the end of the shared extent. If
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* the shared region intersects the mapping, trim the mapping to the
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* start of the shared extent. If there are no shared regions that
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* overlap, just return the original extent.
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*/
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int
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xfs_reflink_trim_around_shared(
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struct xfs_inode *ip,
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struct xfs_bmbt_irec *irec,
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bool *shared)
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{
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xfs_agnumber_t agno;
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xfs_agblock_t agbno;
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xfs_extlen_t aglen;
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xfs_agblock_t fbno;
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xfs_extlen_t flen;
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int error = 0;
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/* Holes, unwritten, and delalloc extents cannot be shared */
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if (!xfs_is_cow_inode(ip) || !xfs_bmap_is_written_extent(irec)) {
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*shared = false;
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return 0;
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}
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trace_xfs_reflink_trim_around_shared(ip, irec);
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agno = XFS_FSB_TO_AGNO(ip->i_mount, irec->br_startblock);
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agbno = XFS_FSB_TO_AGBNO(ip->i_mount, irec->br_startblock);
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aglen = irec->br_blockcount;
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error = xfs_reflink_find_shared(ip->i_mount, NULL, agno, agbno,
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aglen, &fbno, &flen, true);
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if (error)
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return error;
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*shared = false;
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if (fbno == NULLAGBLOCK) {
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/* No shared blocks at all. */
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return 0;
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} else if (fbno == agbno) {
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/*
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* The start of this extent is shared. Truncate the
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* mapping at the end of the shared region so that a
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* subsequent iteration starts at the start of the
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* unshared region.
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*/
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irec->br_blockcount = flen;
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*shared = true;
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return 0;
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} else {
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/*
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* There's a shared extent midway through this extent.
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* Truncate the mapping at the start of the shared
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* extent so that a subsequent iteration starts at the
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* start of the shared region.
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*/
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irec->br_blockcount = fbno - agbno;
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return 0;
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}
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}
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int
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xfs_bmap_trim_cow(
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struct xfs_inode *ip,
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struct xfs_bmbt_irec *imap,
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bool *shared)
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{
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/* We can't update any real extents in always COW mode. */
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if (xfs_is_always_cow_inode(ip) &&
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!isnullstartblock(imap->br_startblock)) {
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*shared = true;
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return 0;
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}
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/* Trim the mapping to the nearest shared extent boundary. */
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return xfs_reflink_trim_around_shared(ip, imap, shared);
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}
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static int
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xfs_reflink_convert_cow_locked(
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struct xfs_inode *ip,
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xfs_fileoff_t offset_fsb,
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xfs_filblks_t count_fsb)
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{
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struct xfs_iext_cursor icur;
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struct xfs_bmbt_irec got;
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struct xfs_btree_cur *dummy_cur = NULL;
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int dummy_logflags;
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int error = 0;
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if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got))
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return 0;
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do {
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if (got.br_startoff >= offset_fsb + count_fsb)
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break;
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if (got.br_state == XFS_EXT_NORM)
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continue;
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if (WARN_ON_ONCE(isnullstartblock(got.br_startblock)))
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return -EIO;
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xfs_trim_extent(&got, offset_fsb, count_fsb);
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if (!got.br_blockcount)
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continue;
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got.br_state = XFS_EXT_NORM;
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error = xfs_bmap_add_extent_unwritten_real(NULL, ip,
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XFS_COW_FORK, &icur, &dummy_cur, &got,
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&dummy_logflags);
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if (error)
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return error;
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} while (xfs_iext_next_extent(ip->i_cowfp, &icur, &got));
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return error;
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}
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/* Convert all of the unwritten CoW extents in a file's range to real ones. */
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int
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xfs_reflink_convert_cow(
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struct xfs_inode *ip,
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xfs_off_t offset,
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xfs_off_t count)
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{
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struct xfs_mount *mp = ip->i_mount;
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xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
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xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
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xfs_filblks_t count_fsb = end_fsb - offset_fsb;
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int error;
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ASSERT(count != 0);
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xfs_ilock(ip, XFS_ILOCK_EXCL);
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error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
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xfs_iunlock(ip, XFS_ILOCK_EXCL);
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return error;
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}
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/*
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* Find the extent that maps the given range in the COW fork. Even if the extent
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* is not shared we might have a preallocation for it in the COW fork. If so we
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* use it that rather than trigger a new allocation.
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*/
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static int
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xfs_find_trim_cow_extent(
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struct xfs_inode *ip,
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struct xfs_bmbt_irec *imap,
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struct xfs_bmbt_irec *cmap,
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bool *shared,
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bool *found)
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{
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xfs_fileoff_t offset_fsb = imap->br_startoff;
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xfs_filblks_t count_fsb = imap->br_blockcount;
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struct xfs_iext_cursor icur;
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*found = false;
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/*
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* If we don't find an overlapping extent, trim the range we need to
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* allocate to fit the hole we found.
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*/
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if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, cmap))
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cmap->br_startoff = offset_fsb + count_fsb;
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if (cmap->br_startoff > offset_fsb) {
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xfs_trim_extent(imap, imap->br_startoff,
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cmap->br_startoff - imap->br_startoff);
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return xfs_bmap_trim_cow(ip, imap, shared);
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}
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*shared = true;
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if (isnullstartblock(cmap->br_startblock)) {
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xfs_trim_extent(imap, cmap->br_startoff, cmap->br_blockcount);
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return 0;
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}
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/* real extent found - no need to allocate */
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xfs_trim_extent(cmap, offset_fsb, count_fsb);
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*found = true;
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return 0;
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}
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/* Allocate all CoW reservations covering a range of blocks in a file. */
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int
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xfs_reflink_allocate_cow(
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struct xfs_inode *ip,
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struct xfs_bmbt_irec *imap,
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struct xfs_bmbt_irec *cmap,
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bool *shared,
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uint *lockmode,
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bool convert_now)
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{
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struct xfs_mount *mp = ip->i_mount;
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xfs_fileoff_t offset_fsb = imap->br_startoff;
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xfs_filblks_t count_fsb = imap->br_blockcount;
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struct xfs_trans *tp;
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int nimaps, error = 0;
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bool found;
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xfs_filblks_t resaligned;
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xfs_extlen_t resblks = 0;
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ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
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if (!ip->i_cowfp) {
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ASSERT(!xfs_is_reflink_inode(ip));
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xfs_ifork_init_cow(ip);
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}
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error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
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if (error || !*shared)
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return error;
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if (found)
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goto convert;
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resaligned = xfs_aligned_fsb_count(imap->br_startoff,
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imap->br_blockcount, xfs_get_cowextsz_hint(ip));
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resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
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xfs_iunlock(ip, *lockmode);
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*lockmode = 0;
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error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, resblks, 0,
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false, &tp);
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if (error)
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return error;
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*lockmode = XFS_ILOCK_EXCL;
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/*
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* Check for an overlapping extent again now that we dropped the ilock.
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*/
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error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
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if (error || !*shared)
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goto out_trans_cancel;
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if (found) {
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xfs_trans_cancel(tp);
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goto convert;
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}
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/* Allocate the entire reservation as unwritten blocks. */
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nimaps = 1;
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error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
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XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, 0, cmap,
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&nimaps);
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if (error)
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goto out_trans_cancel;
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|
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xfs_inode_set_cowblocks_tag(ip);
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error = xfs_trans_commit(tp);
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if (error)
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return error;
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|
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/*
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* Allocation succeeded but the requested range was not even partially
|
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* satisfied? Bail out!
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*/
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if (nimaps == 0)
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return -ENOSPC;
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convert:
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xfs_trim_extent(cmap, offset_fsb, count_fsb);
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/*
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* COW fork extents are supposed to remain unwritten until we're ready
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* to initiate a disk write. For direct I/O we are going to write the
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* data and need the conversion, but for buffered writes we're done.
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*/
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if (!convert_now || cmap->br_state == XFS_EXT_NORM)
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return 0;
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trace_xfs_reflink_convert_cow(ip, cmap);
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return xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
|
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|
|
out_trans_cancel:
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xfs_trans_cancel(tp);
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return error;
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}
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|
|
/*
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|
* Cancel CoW reservations for some block range of an inode.
|
|
*
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* 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.
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*
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* Caller must have already joined the inode to the current transaction. The
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* inode will be joined to the transaction returned to the caller.
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|
*/
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|
int
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|
xfs_reflink_cancel_cow_blocks(
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struct xfs_inode *ip,
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struct xfs_trans **tpp,
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xfs_fileoff_t offset_fsb,
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xfs_fileoff_t end_fsb,
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bool cancel_real)
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|
{
|
|
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;
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|
|
if (!xfs_inode_has_cow_data(ip))
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|
return 0;
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|
if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
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|
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. */
|
|
xfs_refcount_free_cow_extent(*tpp, del.br_startblock,
|
|
del.br_blockcount);
|
|
|
|
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_quota_unreserve_blkres(ip,
|
|
del.br_blockcount);
|
|
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(ip->i_cowfp);
|
|
|
|
offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
|
|
if (count == NULLFILEOFF)
|
|
end_fsb = NULLFILEOFF;
|
|
else
|
|
end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
|
|
|
|
/* Start a rolling transaction to remove the mappings */
|
|
error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
|
|
0, 0, 0, &tp);
|
|
if (error)
|
|
goto out;
|
|
|
|
xfs_ilock(ip, XFS_ILOCK_EXCL);
|
|
xfs_trans_ijoin(tp, ip, 0);
|
|
|
|
/* Scrape out the old CoW reservations */
|
|
error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb,
|
|
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 part of the CoW fork into the data fork.
|
|
*
|
|
* We aim to remap the range starting at @offset_fsb and ending at @end_fsb
|
|
* into the data fork; this function will remap what it can (at the end of the
|
|
* range) and update @end_fsb appropriately. Each remap gets its own
|
|
* transaction because we can end up merging and splitting bmbt blocks for
|
|
* every remap operation and we'd like to keep the block reservation
|
|
* requirements as low as possible.
|
|
*/
|
|
STATIC int
|
|
xfs_reflink_end_cow_extent(
|
|
struct xfs_inode *ip,
|
|
xfs_fileoff_t offset_fsb,
|
|
xfs_fileoff_t *end_fsb)
|
|
{
|
|
struct xfs_bmbt_irec got, del;
|
|
struct xfs_iext_cursor icur;
|
|
struct xfs_mount *mp = ip->i_mount;
|
|
struct xfs_trans *tp;
|
|
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
|
|
xfs_filblks_t rlen;
|
|
unsigned int resblks;
|
|
int error;
|
|
|
|
/* No COW extents? That's easy! */
|
|
if (ifp->if_bytes == 0) {
|
|
*end_fsb = offset_fsb;
|
|
return 0;
|
|
}
|
|
|
|
resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
|
|
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
|
|
XFS_TRANS_RESERVE, &tp);
|
|
if (error)
|
|
return error;
|
|
|
|
/*
|
|
* Lock the inode. We have to ijoin without automatic unlock because
|
|
* the lead transaction is the refcountbt record deletion; the data
|
|
* fork update follows as a deferred log item.
|
|
*/
|
|
xfs_ilock(ip, XFS_ILOCK_EXCL);
|
|
xfs_trans_ijoin(tp, ip, 0);
|
|
|
|
error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
|
|
XFS_IEXT_REFLINK_END_COW_CNT);
|
|
if (error)
|
|
goto out_cancel;
|
|
|
|
/*
|
|
* 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) ||
|
|
got.br_startoff + got.br_blockcount <= offset_fsb) {
|
|
*end_fsb = offset_fsb;
|
|
goto out_cancel;
|
|
}
|
|
|
|
/*
|
|
* Structure copy @got into @del, then trim @del to the range that we
|
|
* were asked to remap. We preserve @got for the eventual CoW fork
|
|
* deletion; from now on @del represents the mapping that we're
|
|
* actually remapping.
|
|
*/
|
|
del = got;
|
|
xfs_trim_extent(&del, offset_fsb, *end_fsb - offset_fsb);
|
|
|
|
ASSERT(del.br_blockcount > 0);
|
|
|
|
/*
|
|
* Only remap real extents that contain data. With AIO, speculative
|
|
* preallocations can leak into the range we are called upon, and we
|
|
* need to skip them.
|
|
*/
|
|
if (!xfs_bmap_is_written_extent(&got)) {
|
|
*end_fsb = del.br_startoff;
|
|
goto out_cancel;
|
|
}
|
|
|
|
/* Unmap the old blocks in the data fork. */
|
|
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. */
|
|
xfs_trim_extent(&del, del.br_startoff + rlen, del.br_blockcount - rlen);
|
|
trace_xfs_reflink_cow_remap(ip, &del);
|
|
|
|
/* Free the CoW orphan record. */
|
|
xfs_refcount_free_cow_extent(tp, del.br_startblock, del.br_blockcount);
|
|
|
|
/* Map the new blocks into the data fork. */
|
|
xfs_bmap_map_extent(tp, ip, &del);
|
|
|
|
/* 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_trans_commit(tp);
|
|
xfs_iunlock(ip, XFS_ILOCK_EXCL);
|
|
if (error)
|
|
return error;
|
|
|
|
/* Update the caller about how much progress we made. */
|
|
*end_fsb = del.br_startoff;
|
|
return 0;
|
|
|
|
out_cancel:
|
|
xfs_trans_cancel(tp);
|
|
xfs_iunlock(ip, XFS_ILOCK_EXCL);
|
|
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)
|
|
{
|
|
xfs_fileoff_t offset_fsb;
|
|
xfs_fileoff_t end_fsb;
|
|
int error = 0;
|
|
|
|
trace_xfs_reflink_end_cow(ip, offset, count);
|
|
|
|
offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
|
|
end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
|
|
|
|
/*
|
|
* Walk backwards until we're out of the I/O range. The loop function
|
|
* repeatedly cycles the ILOCK to allocate one transaction per remapped
|
|
* extent.
|
|
*
|
|
* If we're being called by writeback then the pages will still
|
|
* have PageWriteback set, which prevents races with reflink remapping
|
|
* and truncate. Reflink remapping prevents races with writeback by
|
|
* taking the iolock and mmaplock before flushing the pages and
|
|
* remapping, which means there won't be any further writeback or page
|
|
* cache dirtying until the reflink completes.
|
|
*
|
|
* We should never have two threads issuing writeback for the same file
|
|
* region. There are also have post-eof checks in the writeback
|
|
* preparation code so that we don't bother writing out pages that are
|
|
* about to be truncated.
|
|
*
|
|
* If we're being called as part of directio write completion, the dio
|
|
* count is still elevated, which reflink and truncate will wait for.
|
|
* Reflink remapping takes the iolock and mmaplock and waits for
|
|
* pending dio to finish, which should prevent any directio until the
|
|
* remap completes. Multiple concurrent directio writes to the same
|
|
* region are handled by end_cow processing only occurring for the
|
|
* threads which succeed; the outcome of multiple overlapping direct
|
|
* writes is not well defined anyway.
|
|
*
|
|
* It's possible that a buffered write and a direct write could collide
|
|
* here (the buffered write stumbles in after the dio flushes and
|
|
* invalidates the page cache and immediately queues writeback), but we
|
|
* have never supported this 100%. If either disk write succeeds the
|
|
* blocks will be remapped.
|
|
*/
|
|
while (end_fsb > offset_fsb && !error)
|
|
error = xfs_reflink_end_cow_extent(ip, offset_fsb, &end_fsb);
|
|
|
|
if (error)
|
|
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)
|
|
{
|
|
struct xfs_perag *pag;
|
|
xfs_agnumber_t agno;
|
|
int error = 0;
|
|
|
|
if (!xfs_sb_version_hasreflink(&mp->m_sb))
|
|
return 0;
|
|
|
|
for_each_perag(mp, agno, pag) {
|
|
error = xfs_refcount_recover_cow_leftovers(mp, pag);
|
|
if (error) {
|
|
xfs_perag_put(pag);
|
|
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_diflags2 |= 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_diflags2 |= 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.
|
|
*/
|
|
int
|
|
xfs_reflink_update_dest(
|
|
struct xfs_inode *dest,
|
|
xfs_off_t newlen,
|
|
xfs_extlen_t cowextsize,
|
|
unsigned int remap_flags)
|
|
{
|
|
struct xfs_mount *mp = dest->i_mount;
|
|
struct xfs_trans *tp;
|
|
int error;
|
|
|
|
if (newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
|
|
return 0;
|
|
|
|
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
|
|
if (error)
|
|
goto out_error;
|
|
|
|
xfs_ilock(dest, XFS_ILOCK_EXCL);
|
|
xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
|
|
|
|
if (newlen > i_size_read(VFS_I(dest))) {
|
|
trace_xfs_reflink_update_inode_size(dest, newlen);
|
|
i_size_write(VFS_I(dest), newlen);
|
|
dest->i_disk_size = newlen;
|
|
}
|
|
|
|
if (cowextsize) {
|
|
dest->i_cowextsize = cowextsize;
|
|
dest->i_diflags2 |= XFS_DIFLAG2_COWEXTSIZE;
|
|
}
|
|
|
|
xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
|
|
|
|
error = xfs_trans_commit(tp);
|
|
if (error)
|
|
goto out_error;
|
|
return error;
|
|
|
|
out_error:
|
|
trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Do we have enough reserve in this AG to handle a reflink? The refcount
|
|
* btree already reserved all the space it needs, but the rmap btree can grow
|
|
* infinitely, so we won't allow more reflinks when the AG is down to the
|
|
* btree reserves.
|
|
*/
|
|
static int
|
|
xfs_reflink_ag_has_free_space(
|
|
struct xfs_mount *mp,
|
|
xfs_agnumber_t agno)
|
|
{
|
|
struct xfs_perag *pag;
|
|
int error = 0;
|
|
|
|
if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
|
|
return 0;
|
|
|
|
pag = xfs_perag_get(mp, agno);
|
|
if (xfs_ag_resv_critical(pag, XFS_AG_RESV_RMAPBT) ||
|
|
xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA))
|
|
error = -ENOSPC;
|
|
xfs_perag_put(pag);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Remap the given extent into the file. The dmap blockcount will be set to
|
|
* the number of blocks that were actually remapped.
|
|
*/
|
|
STATIC int
|
|
xfs_reflink_remap_extent(
|
|
struct xfs_inode *ip,
|
|
struct xfs_bmbt_irec *dmap,
|
|
xfs_off_t new_isize)
|
|
{
|
|
struct xfs_bmbt_irec smap;
|
|
struct xfs_mount *mp = ip->i_mount;
|
|
struct xfs_trans *tp;
|
|
xfs_off_t newlen;
|
|
int64_t qdelta = 0;
|
|
unsigned int resblks;
|
|
bool quota_reserved = true;
|
|
bool smap_real;
|
|
bool dmap_written = xfs_bmap_is_written_extent(dmap);
|
|
int iext_delta = 0;
|
|
int nimaps;
|
|
int error;
|
|
|
|
/*
|
|
* Start a rolling transaction to switch the mappings.
|
|
*
|
|
* Adding a written extent to the extent map can cause a bmbt split,
|
|
* and removing a mapped extent from the extent can cause a bmbt split.
|
|
* The two operations cannot both cause a split since they operate on
|
|
* the same index in the bmap btree, so we only need a reservation for
|
|
* one bmbt split if either thing is happening. However, we haven't
|
|
* locked the inode yet, so we reserve assuming this is the case.
|
|
*
|
|
* The first allocation call tries to reserve enough space to handle
|
|
* mapping dmap into a sparse part of the file plus the bmbt split. We
|
|
* haven't locked the inode or read the existing mapping yet, so we do
|
|
* not know for sure that we need the space. This should succeed most
|
|
* of the time.
|
|
*
|
|
* If the first attempt fails, try again but reserving only enough
|
|
* space to handle a bmbt split. This is the hard minimum requirement,
|
|
* and we revisit quota reservations later when we know more about what
|
|
* we're remapping.
|
|
*/
|
|
resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
|
|
error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
|
|
resblks + dmap->br_blockcount, 0, false, &tp);
|
|
if (error == -EDQUOT || error == -ENOSPC) {
|
|
quota_reserved = false;
|
|
error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
|
|
resblks, 0, false, &tp);
|
|
}
|
|
if (error)
|
|
goto out;
|
|
|
|
/*
|
|
* Read what's currently mapped in the destination file into smap.
|
|
* If smap isn't a hole, we will have to remove it before we can add
|
|
* dmap to the destination file.
|
|
*/
|
|
nimaps = 1;
|
|
error = xfs_bmapi_read(ip, dmap->br_startoff, dmap->br_blockcount,
|
|
&smap, &nimaps, 0);
|
|
if (error)
|
|
goto out_cancel;
|
|
ASSERT(nimaps == 1 && smap.br_startoff == dmap->br_startoff);
|
|
smap_real = xfs_bmap_is_real_extent(&smap);
|
|
|
|
/*
|
|
* We can only remap as many blocks as the smaller of the two extent
|
|
* maps, because we can only remap one extent at a time.
|
|
*/
|
|
dmap->br_blockcount = min(dmap->br_blockcount, smap.br_blockcount);
|
|
ASSERT(dmap->br_blockcount == smap.br_blockcount);
|
|
|
|
trace_xfs_reflink_remap_extent_dest(ip, &smap);
|
|
|
|
/*
|
|
* Two extents mapped to the same physical block must not have
|
|
* different states; that's filesystem corruption. Move on to the next
|
|
* extent if they're both holes or both the same physical extent.
|
|
*/
|
|
if (dmap->br_startblock == smap.br_startblock) {
|
|
if (dmap->br_state != smap.br_state)
|
|
error = -EFSCORRUPTED;
|
|
goto out_cancel;
|
|
}
|
|
|
|
/* If both extents are unwritten, leave them alone. */
|
|
if (dmap->br_state == XFS_EXT_UNWRITTEN &&
|
|
smap.br_state == XFS_EXT_UNWRITTEN)
|
|
goto out_cancel;
|
|
|
|
/* No reflinking if the AG of the dest mapping is low on space. */
|
|
if (dmap_written) {
|
|
error = xfs_reflink_ag_has_free_space(mp,
|
|
XFS_FSB_TO_AGNO(mp, dmap->br_startblock));
|
|
if (error)
|
|
goto out_cancel;
|
|
}
|
|
|
|
/*
|
|
* Increase quota reservation if we think the quota block counter for
|
|
* this file could increase.
|
|
*
|
|
* If we are mapping a written extent into the file, we need to have
|
|
* enough quota block count reservation to handle the blocks in that
|
|
* extent. We log only the delta to the quota block counts, so if the
|
|
* extent we're unmapping also has blocks allocated to it, we don't
|
|
* need a quota reservation for the extent itself.
|
|
*
|
|
* Note that if we're replacing a delalloc reservation with a written
|
|
* extent, we have to take the full quota reservation because removing
|
|
* the delalloc reservation gives the block count back to the quota
|
|
* count. This is suboptimal, but the VFS flushed the dest range
|
|
* before we started. That should have removed all the delalloc
|
|
* reservations, but we code defensively.
|
|
*
|
|
* xfs_trans_alloc_inode above already tried to grab an even larger
|
|
* quota reservation, and kicked off a blockgc scan if it couldn't.
|
|
* If we can't get a potentially smaller quota reservation now, we're
|
|
* done.
|
|
*/
|
|
if (!quota_reserved && !smap_real && dmap_written) {
|
|
error = xfs_trans_reserve_quota_nblks(tp, ip,
|
|
dmap->br_blockcount, 0, false);
|
|
if (error)
|
|
goto out_cancel;
|
|
}
|
|
|
|
if (smap_real)
|
|
++iext_delta;
|
|
|
|
if (dmap_written)
|
|
++iext_delta;
|
|
|
|
error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK, iext_delta);
|
|
if (error)
|
|
goto out_cancel;
|
|
|
|
if (smap_real) {
|
|
/*
|
|
* If the extent we're unmapping is backed by storage (written
|
|
* or not), unmap the extent and drop its refcount.
|
|
*/
|
|
xfs_bmap_unmap_extent(tp, ip, &smap);
|
|
xfs_refcount_decrease_extent(tp, &smap);
|
|
qdelta -= smap.br_blockcount;
|
|
} else if (smap.br_startblock == DELAYSTARTBLOCK) {
|
|
xfs_filblks_t len = smap.br_blockcount;
|
|
|
|
/*
|
|
* If the extent we're unmapping is a delalloc reservation,
|
|
* we can use the regular bunmapi function to release the
|
|
* incore state. Dropping the delalloc reservation takes care
|
|
* of the quota reservation for us.
|
|
*/
|
|
error = __xfs_bunmapi(NULL, ip, smap.br_startoff, &len, 0, 1);
|
|
if (error)
|
|
goto out_cancel;
|
|
ASSERT(len == 0);
|
|
}
|
|
|
|
/*
|
|
* If the extent we're sharing is backed by written storage, increase
|
|
* its refcount and map it into the file.
|
|
*/
|
|
if (dmap_written) {
|
|
xfs_refcount_increase_extent(tp, dmap);
|
|
xfs_bmap_map_extent(tp, ip, dmap);
|
|
qdelta += dmap->br_blockcount;
|
|
}
|
|
|
|
xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, qdelta);
|
|
|
|
/* Update dest isize if needed. */
|
|
newlen = XFS_FSB_TO_B(mp, dmap->br_startoff + dmap->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_disk_size = newlen;
|
|
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
|
|
}
|
|
|
|
/* Commit everything and unlock. */
|
|
error = xfs_trans_commit(tp);
|
|
goto out_unlock;
|
|
|
|
out_cancel:
|
|
xfs_trans_cancel(tp);
|
|
out_unlock:
|
|
xfs_iunlock(ip, XFS_ILOCK_EXCL);
|
|
out:
|
|
if (error)
|
|
trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_);
|
|
return error;
|
|
}
|
|
|
|
/* Remap a range of one file to the other. */
|
|
int
|
|
xfs_reflink_remap_blocks(
|
|
struct xfs_inode *src,
|
|
loff_t pos_in,
|
|
struct xfs_inode *dest,
|
|
loff_t pos_out,
|
|
loff_t remap_len,
|
|
loff_t *remapped)
|
|
{
|
|
struct xfs_bmbt_irec imap;
|
|
struct xfs_mount *mp = src->i_mount;
|
|
xfs_fileoff_t srcoff = XFS_B_TO_FSBT(mp, pos_in);
|
|
xfs_fileoff_t destoff = XFS_B_TO_FSBT(mp, pos_out);
|
|
xfs_filblks_t len;
|
|
xfs_filblks_t remapped_len = 0;
|
|
xfs_off_t new_isize = pos_out + remap_len;
|
|
int nimaps;
|
|
int error = 0;
|
|
|
|
len = min_t(xfs_filblks_t, XFS_B_TO_FSB(mp, remap_len),
|
|
XFS_MAX_FILEOFF);
|
|
|
|
trace_xfs_reflink_remap_blocks(src, srcoff, len, dest, destoff);
|
|
|
|
while (len > 0) {
|
|
unsigned int lock_mode;
|
|
|
|
/* 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)
|
|
break;
|
|
/*
|
|
* The caller supposedly flushed all dirty pages in the source
|
|
* file range, which means that writeback should have allocated
|
|
* or deleted all delalloc reservations in that range. If we
|
|
* find one, that's a good sign that something is seriously
|
|
* wrong here.
|
|
*/
|
|
ASSERT(nimaps == 1 && imap.br_startoff == srcoff);
|
|
if (imap.br_startblock == DELAYSTARTBLOCK) {
|
|
ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
|
|
error = -EFSCORRUPTED;
|
|
break;
|
|
}
|
|
|
|
trace_xfs_reflink_remap_extent_src(src, &imap);
|
|
|
|
/* Remap into the destination file at the given offset. */
|
|
imap.br_startoff = destoff;
|
|
error = xfs_reflink_remap_extent(dest, &imap, new_isize);
|
|
if (error)
|
|
break;
|
|
|
|
if (fatal_signal_pending(current)) {
|
|
error = -EINTR;
|
|
break;
|
|
}
|
|
|
|
/* Advance drange/srange */
|
|
srcoff += imap.br_blockcount;
|
|
destoff += imap.br_blockcount;
|
|
len -= imap.br_blockcount;
|
|
remapped_len += imap.br_blockcount;
|
|
}
|
|
|
|
if (error)
|
|
trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
|
|
*remapped = min_t(loff_t, remap_len,
|
|
XFS_FSB_TO_B(src->i_mount, remapped_len));
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* 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_buffered_write_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.
|
|
*/
|
|
int
|
|
xfs_reflink_remap_prep(
|
|
struct file *file_in,
|
|
loff_t pos_in,
|
|
struct file *file_out,
|
|
loff_t pos_out,
|
|
loff_t *len,
|
|
unsigned int remap_flags)
|
|
{
|
|
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);
|
|
int ret;
|
|
|
|
/* Lock both files against IO */
|
|
ret = xfs_ilock2_io_mmap(src, dest);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/* 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 = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
|
|
len, remap_flags);
|
|
if (ret || *len == 0)
|
|
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;
|
|
|
|
return 0;
|
|
out_unlock:
|
|
xfs_iunlock2_io_mmap(src, dest);
|
|
return ret;
|
|
}
|
|
|
|
/* 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);
|
|
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, XFS_MAX_FILEOFF,
|
|
true);
|
|
if (error)
|
|
return error;
|
|
|
|
/* Clear the inode flag. */
|
|
trace_xfs_reflink_unset_inode_flag(ip);
|
|
ip->i_diflags2 &= ~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 inode *inode = VFS_I(ip);
|
|
int error;
|
|
|
|
if (!xfs_is_reflink_inode(ip))
|
|
return 0;
|
|
|
|
trace_xfs_reflink_unshare(ip, offset, len);
|
|
|
|
inode_dio_wait(inode);
|
|
|
|
error = iomap_file_unshare(inode, offset, len,
|
|
&xfs_buffered_write_iomap_ops);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = filemap_write_and_wait_range(inode->i_mapping, offset,
|
|
offset + len - 1);
|
|
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:
|
|
trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
|
|
return error;
|
|
}
|