// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2016 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <[email protected]>
*/
#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_inode.h"
#include "xfs_trans.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_trace.h"
#include "xfs_icache.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.h"
#include "xfs_reflink.h"
#include "xfs_iomap.h"
#include "xfs_ag.h"
#include "xfs_ag_resv.h"
#include "xfs_health.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.
*/
static int
xfs_reflink_find_shared(
struct xfs_perag *pag,
struct xfs_trans *tp,
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(pag, tp, 0, &agbp);
if (error)
return error;
cur = xfs_refcountbt_init_cursor(pag->pag_mount, tp, agbp, pag);
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)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_perag *pag;
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_cow_inode(ip) || !xfs_bmap_is_written_extent(irec)) {
*shared = false;
return 0;
}
trace_xfs_reflink_trim_around_shared(ip, irec);
pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, irec->br_startblock));
agbno = XFS_FSB_TO_AGBNO(mp, irec->br_startblock);
aglen = irec->br_blockcount;
error = xfs_reflink_find_shared(pag, NULL, agbno, aglen, &fbno, &flen,
true);
xfs_perag_put(pag);
if (error)
return error;
*shared = false;
if (fbno == NULLAGBLOCK) {
/* No shared blocks at all. */
return 0;
}
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;
return 0;
}
/*
* 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;
return 0;
}
int
xfs_bmap_trim_cow(
struct xfs_inode *ip,
struct xfs_bmbt_irec *imap,
bool *shared)
{
/* We can't update any real extents in always COW mode. */
if (xfs_is_always_cow_inode(ip) &&
!isnullstartblock(imap->br_startblock)) {
*shared = true;
return 0;
}
/* Trim the mapping to the nearest shared extent boundary. */
return xfs_reflink_trim_around_shared(ip, imap, shared);
}
static int
xfs_reflink_convert_cow_locked(
struct xfs_inode *ip,
xfs_fileoff_t offset_fsb,
xfs_filblks_t count_fsb)
{
struct xfs_iext_cursor icur;
struct xfs_bmbt_irec got;
struct xfs_btree_cur *dummy_cur = NULL;
int dummy_logflags;
int error = 0;
if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got))
return 0;
do {
if (got.br_startoff >= offset_fsb + count_fsb)
break;
if (got.br_state == XFS_EXT_NORM)
continue;
if (WARN_ON_ONCE(isnullstartblock(got.br_startblock)))
return -EIO;
xfs_trim_extent(&got, offset_fsb, count_fsb);
if (!got.br_blockcount)
continue;
got.br_state = XFS_EXT_NORM;
error = xfs_bmap_add_extent_unwritten_real(NULL, ip,
XFS_COW_FORK, &icur, &dummy_cur, &got,
&dummy_logflags);
if (error)
return error;
} while (xfs_iext_next_extent(ip->i_cowfp, &icur, &got));
return error;
}
/* 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;
int error;
ASSERT(count != 0);
xfs_ilock(ip, XFS_ILOCK_EXCL);
error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
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,
struct xfs_bmbt_irec *cmap,
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;
*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, cmap))
cmap->br_startoff = offset_fsb + count_fsb;
if (cmap->br_startoff > offset_fsb) {
xfs_trim_extent(imap, imap->br_startoff,
cmap->br_startoff - imap->br_startoff);
return xfs_bmap_trim_cow(ip, imap, shared);
}
*shared = true;
if (isnullstartblock(cmap->br_startblock)) {
xfs_trim_extent(imap, cmap->br_startoff, cmap->br_blockcount);
return 0;
}
/* real extent found - no need to allocate */
xfs_trim_extent(cmap, offset_fsb, count_fsb);
*found = true;
return 0;
}
static int
xfs_reflink_convert_unwritten(
struct xfs_inode *ip,
struct xfs_bmbt_irec *imap,
struct xfs_bmbt_irec *cmap,
bool convert_now)
{
xfs_fileoff_t offset_fsb = imap->br_startoff;
xfs_filblks_t count_fsb = imap->br_blockcount;
int error;
/*
* cmap might larger than imap due to cowextsize hint.
*/
xfs_trim_extent(cmap, offset_fsb, count_fsb);
/*
* COW fork extents are supposed to remain unwritten until we're ready
* to initiate a disk write. For direct I/O we are going to write the
* data and need the conversion, but for buffered writes we're done.
*/
if (!convert_now || cmap->br_state == XFS_EXT_NORM)
return 0;
trace_xfs_reflink_convert_cow(ip, cmap);
error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
if (!error)
cmap->br_state = XFS_EXT_NORM;
return error;
}
static int
xfs_reflink_fill_cow_hole(
struct xfs_inode *ip,
struct xfs_bmbt_irec *imap,
struct xfs_bmbt_irec *cmap,
bool *shared,
uint *lockmode,
bool convert_now)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_trans *tp;
xfs_filblks_t resaligned;
xfs_extlen_t resblks;
int nimaps;
int error;
bool found;
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);
*lockmode = 0;
error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, resblks, 0,
false, &tp);
if (error)
return error;
*lockmode = XFS_ILOCK_EXCL;
error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
if (error || !*shared)
goto out_trans_cancel;
if (found) {
xfs_trans_cancel(tp);
goto convert;
}
/* 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, 0, cmap,
&nimaps);
if (error)
goto out_trans_cancel;
xfs_inode_set_cowblocks_tag(ip);
error = xfs_trans_commit(tp);
if (error)
return error;
convert:
return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now);
out_trans_cancel:
xfs_trans_cancel(tp);
return error;
}
static int
xfs_reflink_fill_delalloc(
struct xfs_inode *ip,
struct xfs_bmbt_irec *imap,
struct xfs_bmbt_irec *cmap,
bool *shared,
uint *lockmode,
bool convert_now)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_trans *tp;
int nimaps;
int error;
bool found;
do {
xfs_iunlock(ip, *lockmode);
*lockmode = 0;
error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, 0, 0,
false, &tp);
if (error)
return error;
*lockmode = XFS_ILOCK_EXCL;
error = xfs_find_trim_cow_extent(ip, imap, cmap, shared,
&found);
if (error || !*shared)
goto out_trans_cancel;
if (found) {
xfs_trans_cancel(tp);
break;
}
ASSERT(isnullstartblock(cmap->br_startblock) ||
cmap->br_startblock == DELAYSTARTBLOCK);
/*
* Replace delalloc reservation with an unwritten extent.
*/
nimaps = 1;
error = xfs_bmapi_write(tp, ip, cmap->br_startoff,
cmap->br_blockcount,
XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, 0,
cmap, &nimaps);
if (error)
goto out_trans_cancel;
xfs_inode_set_cowblocks_tag(ip);
error = xfs_trans_commit(tp);
if (error)
return error;
} while (cmap->br_startoff + cmap->br_blockcount <= imap->br_startoff);
return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now);
out_trans_cancel:
xfs_trans_cancel(tp);
return error;
}
/* 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,
struct xfs_bmbt_irec *cmap,
bool *shared,
uint *lockmode,
bool convert_now)
{
int error;
bool found;
xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
if (!ip->i_cowfp) {
ASSERT(!xfs_is_reflink_inode(ip));
xfs_ifork_init_cow(ip);
}
error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
if (error || !*shared)
return error;
/* CoW fork has a real extent */
if (found)
return xfs_reflink_convert_unwritten(ip, imap, cmap,
convert_now);
/*
* CoW fork does not have an extent and data extent is shared.
* Allocate a real extent in the CoW fork.
*/
if (cmap->br_startoff > imap->br_startoff)
return xfs_reflink_fill_cow_hole(ip, imap, cmap, shared,
lockmode, convert_now);
/*
* CoW fork has a delalloc reservation. Replace it with a real extent.
* There may or may not be a data fork mapping.
*/
if (isnullstartblock(cmap->br_startblock) ||
cmap->br_startblock == DELAYSTARTBLOCK)
return xfs_reflink_fill_delalloc(ip, imap, cmap, shared,
lockmode, convert_now);
/* Shouldn't get here. */
ASSERT(0);
return -EFSCORRUPTED;
}
/*
* 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)) {
xfs_bmap_del_extent_delay(ip, XFS_COW_FORK, &icur, &got,
&del);
} else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
ASSERT((*tpp)->t_highest_agno == NULLAGNUMBER);
/* Free the CoW orphan record. */
xfs_refcount_free_cow_extent(*tpp, del.br_startblock,
del.br_blockcount);
error = xfs_free_extent_later(*tpp, del.br_startblock,
del.br_blockcount, NULL,
XFS_AG_RESV_NONE, 0);
if (error)
break;
/* 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 */
xfs_quota_unreserve_blkres(ip, del.br_blockcount);
} 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_iext_cursor icur;
struct xfs_bmbt_irec got, del, data;
struct xfs_mount *mp = ip->i_mount;
struct xfs_trans *tp;
struct xfs_ifork *ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
unsigned int resblks;
int nmaps;
int error;
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);
/*
* 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(ip, ifp, *offset_fsb, &icur, &got) ||
got.br_startoff >= end_fsb) {
*offset_fsb = end_fsb;
goto out_cancel;
}
/*
* 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. Preserve @got for the eventual CoW fork
* deletion; from now on @del represents the mapping that we're
* actually remapping.
*/
while (!xfs_bmap_is_written_extent(&got)) {
if (!xfs_iext_next_extent(ifp, &icur, &got) ||
got.br_startoff >= end_fsb) {
*offset_fsb = end_fsb;
goto out_cancel;
}
}
del = got;
xfs_trim_extent(&del, *offset_fsb, end_fsb - *offset_fsb);
error = xfs_iext_count_extend(tp, ip, XFS_DATA_FORK,
XFS_IEXT_REFLINK_END_COW_CNT);
if (error)
goto out_cancel;
/* Grab the corresponding mapping in the data fork. */
nmaps = 1;
error = xfs_bmapi_read(ip, del.br_startoff, del.br_blockcount, &data,
&nmaps, 0);
if (error)
goto out_cancel;
/* We can only remap the smaller of the two extent sizes. */
data.br_blockcount = min(data.br_blockcount, del.br_blockcount);
del.br_blockcount = data.br_blockcount;
trace_xfs_reflink_cow_remap_from(ip, &del);
trace_xfs_reflink_cow_remap_to(ip, &data);
if (xfs_bmap_is_real_extent(&data)) {
/*
* If the extent we're remapping is backed by storage (written
* or not), unmap the extent and drop its refcount.
*/
xfs_bmap_unmap_extent(tp, ip, XFS_DATA_FORK, &data);
xfs_refcount_decrease_extent(tp, &data);
xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
-data.br_blockcount);
} else if (data.br_startblock == DELAYSTARTBLOCK) {
int done;
/*
* If the extent we're remapping 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, data.br_startoff,
data.br_blockcount, 0, 1, &done);
if (error)
goto out_cancel;
ASSERT(done);
}
/* 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, XFS_DATA_FORK, &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. */
*offset_fsb = del.br_startoff + del.br_blockcount;
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 forwards until we've remapped 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 all CoW staging blocks that are still referenced by the ondisk refcount
* metadata. The ondisk metadata does not track which inode created the
* staging extent, so callers must ensure that there are no cached inodes with
* live CoW staging extents.
*/
int
xfs_reflink_recover_cow(
struct xfs_mount *mp)
{
struct xfs_perag *pag;
xfs_agnumber_t agno;
int error = 0;
if (!xfs_has_reflink(mp))
return 0;
for_each_perag(mp, agno, pag) {
error = xfs_refcount_recover_cow_leftovers(mp, pag);
if (error) {
xfs_perag_rele(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_has_rmapbt(mp))
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) {
xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
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_extend(tp, 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, XFS_DATA_FORK, &smap);
xfs_refcount_decrease_extent(tp, &smap);
qdelta -= smap.br_blockcount;
} else if (smap.br_startblock == DELAYSTARTBLOCK) {
int done;
/*
* 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,
smap.br_blockcount, 0, 1, &done);
if (error)
goto out_cancel;
ASSERT(done);
}
/*
* 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, XFS_DATA_FORK, 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);
xfs_bmap_mark_sick(src, XFS_DATA_FORK);
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;
cond_resched();
}
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 xfs_zero_range(ip, isize, pos - isize, NULL);
}
/*
* 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 with non-DAX file. */
if (IS_DAX(inode_in) != IS_DAX(inode_out))
goto out_unlock;
if (!IS_DAX(inode_in))
ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
pos_out, len, remap_flags);
else
ret = dax_remap_file_range_prep(file_in, pos_in, file_out,
pos_out, len, remap_flags, &xfs_read_iomap_ops);
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;
xfs_iflags_set(src, XFS_IREMAPPING);
if (inode_in != inode_out)
xfs_ilock_demote(src, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL);
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;
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) {
struct xfs_perag *pag;
xfs_agblock_t agbno;
xfs_extlen_t aglen;
xfs_agblock_t rbno;
xfs_extlen_t rlen;
if (isnullstartblock(got.br_startblock) ||
got.br_state != XFS_EXT_NORM)
goto next;
pag = xfs_perag_get(mp, 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(pag, tp, agbno, aglen,
&rbno, &rlen, false);
xfs_perag_put(pag);
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);
if (IS_DAX(inode))
error = dax_file_unshare(inode, offset, len,
&xfs_dax_write_iomap_ops);
else
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;
}
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