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linux/fs/xfs/libxfs/xfs_refcount.c
Darrick J. Wong e1a4e37cc7 xfs: try to avoid blowing out the transaction reservation when bunmaping a shared extent 
In a pathological scenario where we are trying to bunmapi a single
extent in which every other block is shared, it's possible that trying
to unmap the entire large extent in a single transaction can generate so
many EFIs that we overflow the transaction reservation.

Therefore, use a heuristic to guess at the number of blocks we can
safely unmap from a reflink file's data fork in an single transaction.
This should prevent problems such as the log head slamming into the tail
and ASSERTs that trigger because we've exceeded the transaction
reservation.

Note that since bunmapi can fail to unmap the entire range, we must also
teach the deferred unmap code to roll into a new transaction whenever we
get low on reservation.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
[hch: random edits, all bugs are my fault]
Signed-off-by: Christoph Hellwig <hch@lst.de>
2017-06-19 08:59:10 -07:00

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/*
* Copyright (C) 2016 Oracle. All Rights Reserved.
*
* Author: Darrick J. Wong <darrick.wong@oracle.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_btree.h"
#include "xfs_bmap.h"
#include "xfs_refcount_btree.h"
#include "xfs_alloc.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_cksum.h"
#include "xfs_trans.h"
#include "xfs_bit.h"
#include "xfs_refcount.h"
#include "xfs_rmap.h"
/* Allowable refcount adjustment amounts. */
enum xfs_refc_adjust_op {
XFS_REFCOUNT_ADJUST_INCREASE = 1,
XFS_REFCOUNT_ADJUST_DECREASE = -1,
XFS_REFCOUNT_ADJUST_COW_ALLOC = 0,
XFS_REFCOUNT_ADJUST_COW_FREE = -1,
};
STATIC int __xfs_refcount_cow_alloc(struct xfs_btree_cur *rcur,
xfs_agblock_t agbno, xfs_extlen_t aglen,
struct xfs_defer_ops *dfops);
STATIC int __xfs_refcount_cow_free(struct xfs_btree_cur *rcur,
xfs_agblock_t agbno, xfs_extlen_t aglen,
struct xfs_defer_ops *dfops);
/*
* Look up the first record less than or equal to [bno, len] in the btree
* given by cur.
*/
int
xfs_refcount_lookup_le(
struct xfs_btree_cur *cur,
xfs_agblock_t bno,
int *stat)
{
trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_private.a.agno, bno,
XFS_LOOKUP_LE);
cur->bc_rec.rc.rc_startblock = bno;
cur->bc_rec.rc.rc_blockcount = 0;
return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
}
/*
* Look up the first record greater than or equal to [bno, len] in the btree
* given by cur.
*/
int
xfs_refcount_lookup_ge(
struct xfs_btree_cur *cur,
xfs_agblock_t bno,
int *stat)
{
trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_private.a.agno, bno,
XFS_LOOKUP_GE);
cur->bc_rec.rc.rc_startblock = bno;
cur->bc_rec.rc.rc_blockcount = 0;
return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
}
/* Convert on-disk record to in-core format. */
static inline void
xfs_refcount_btrec_to_irec(
union xfs_btree_rec *rec,
struct xfs_refcount_irec *irec)
{
irec->rc_startblock = be32_to_cpu(rec->refc.rc_startblock);
irec->rc_blockcount = be32_to_cpu(rec->refc.rc_blockcount);
irec->rc_refcount = be32_to_cpu(rec->refc.rc_refcount);
}
/*
* Get the data from the pointed-to record.
*/
int
xfs_refcount_get_rec(
struct xfs_btree_cur *cur,
struct xfs_refcount_irec *irec,
int *stat)
{
union xfs_btree_rec *rec;
int error;
error = xfs_btree_get_rec(cur, &rec, stat);
if (!error && *stat == 1) {
xfs_refcount_btrec_to_irec(rec, irec);
trace_xfs_refcount_get(cur->bc_mp, cur->bc_private.a.agno,
irec);
}
return error;
}
/*
* Update the record referred to by cur to the value given
* by [bno, len, refcount].
* This either works (return 0) or gets an EFSCORRUPTED error.
*/
STATIC int
xfs_refcount_update(
struct xfs_btree_cur *cur,
struct xfs_refcount_irec *irec)
{
union xfs_btree_rec rec;
int error;
trace_xfs_refcount_update(cur->bc_mp, cur->bc_private.a.agno, irec);
rec.refc.rc_startblock = cpu_to_be32(irec->rc_startblock);
rec.refc.rc_blockcount = cpu_to_be32(irec->rc_blockcount);
rec.refc.rc_refcount = cpu_to_be32(irec->rc_refcount);
error = xfs_btree_update(cur, &rec);
if (error)
trace_xfs_refcount_update_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/*
* Insert the record referred to by cur to the value given
* by [bno, len, refcount].
* This either works (return 0) or gets an EFSCORRUPTED error.
*/
STATIC int
xfs_refcount_insert(
struct xfs_btree_cur *cur,
struct xfs_refcount_irec *irec,
int *i)
{
int error;
trace_xfs_refcount_insert(cur->bc_mp, cur->bc_private.a.agno, irec);
cur->bc_rec.rc.rc_startblock = irec->rc_startblock;
cur->bc_rec.rc.rc_blockcount = irec->rc_blockcount;
cur->bc_rec.rc.rc_refcount = irec->rc_refcount;
error = xfs_btree_insert(cur, i);
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, *i == 1, out_error);
out_error:
if (error)
trace_xfs_refcount_insert_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/*
* Remove the record referred to by cur, then set the pointer to the spot
* where the record could be re-inserted, in case we want to increment or
* decrement the cursor.
* This either works (return 0) or gets an EFSCORRUPTED error.
*/
STATIC int
xfs_refcount_delete(
struct xfs_btree_cur *cur,
int *i)
{
struct xfs_refcount_irec irec;
int found_rec;
int error;
error = xfs_refcount_get_rec(cur, &irec, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
trace_xfs_refcount_delete(cur->bc_mp, cur->bc_private.a.agno, &irec);
error = xfs_btree_delete(cur, i);
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, *i == 1, out_error);
if (error)
goto out_error;
error = xfs_refcount_lookup_ge(cur, irec.rc_startblock, &found_rec);
out_error:
if (error)
trace_xfs_refcount_delete_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/*
* Adjusting the Reference Count
*
* As stated elsewhere, the reference count btree (refcbt) stores
* >1 reference counts for extents of physical blocks. In this
* operation, we're either raising or lowering the reference count of
* some subrange stored in the tree:
*
* <------ adjustment range ------>
* ----+ +---+-----+ +--+--------+---------
* 2 | | 3 | 4 | |17| 55 | 10
* ----+ +---+-----+ +--+--------+---------
* X axis is physical blocks number;
* reference counts are the numbers inside the rectangles
*
* The first thing we need to do is to ensure that there are no
* refcount extents crossing either boundary of the range to be
* adjusted. For any extent that does cross a boundary, split it into
* two extents so that we can increment the refcount of one of the
* pieces later:
*
* <------ adjustment range ------>
* ----+ +---+-----+ +--+--------+----+----
* 2 | | 3 | 2 | |17| 55 | 10 | 10
* ----+ +---+-----+ +--+--------+----+----
*
* For this next step, let's assume that all the physical blocks in
* the adjustment range are mapped to a file and are therefore in use
* at least once. Therefore, we can infer that any gap in the
* refcount tree within the adjustment range represents a physical
* extent with refcount == 1:
*
* <------ adjustment range ------>
* ----+---+---+-----+-+--+--------+----+----
* 2 |"1"| 3 | 2 |1|17| 55 | 10 | 10
* ----+---+---+-----+-+--+--------+----+----
* ^
*
* For each extent that falls within the interval range, figure out
* which extent is to the left or the right of that extent. Now we
* have a left, current, and right extent. If the new reference count
* of the center extent enables us to merge left, center, and right
* into one record covering all three, do so. If the center extent is
* at the left end of the range, abuts the left extent, and its new
* reference count matches the left extent's record, then merge them.
* If the center extent is at the right end of the range, abuts the
* right extent, and the reference counts match, merge those. In the
* example, we can left merge (assuming an increment operation):
*
* <------ adjustment range ------>
* --------+---+-----+-+--+--------+----+----
* 2 | 3 | 2 |1|17| 55 | 10 | 10
* --------+---+-----+-+--+--------+----+----
* ^
*
* For all other extents within the range, adjust the reference count
* or delete it if the refcount falls below 2. If we were
* incrementing, the end result looks like this:
*
* <------ adjustment range ------>
* --------+---+-----+-+--+--------+----+----
* 2 | 4 | 3 |2|18| 56 | 11 | 10
* --------+---+-----+-+--+--------+----+----
*
* The result of a decrement operation looks as such:
*
* <------ adjustment range ------>
* ----+ +---+ +--+--------+----+----
* 2 | | 2 | |16| 54 | 9 | 10
* ----+ +---+ +--+--------+----+----
* DDDD 111111DD
*
* The blocks marked "D" are freed; the blocks marked "1" are only
* referenced once and therefore the record is removed from the
* refcount btree.
*/
/* Next block after this extent. */
static inline xfs_agblock_t
xfs_refc_next(
struct xfs_refcount_irec *rc)
{
return rc->rc_startblock + rc->rc_blockcount;
}
/*
* Split a refcount extent that crosses agbno.
*/
STATIC int
xfs_refcount_split_extent(
struct xfs_btree_cur *cur,
xfs_agblock_t agbno,
bool *shape_changed)
{
struct xfs_refcount_irec rcext, tmp;
int found_rec;
int error;
*shape_changed = false;
error = xfs_refcount_lookup_le(cur, agbno, &found_rec);
if (error)
goto out_error;
if (!found_rec)
return 0;
error = xfs_refcount_get_rec(cur, &rcext, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
if (rcext.rc_startblock == agbno || xfs_refc_next(&rcext) <= agbno)
return 0;
*shape_changed = true;
trace_xfs_refcount_split_extent(cur->bc_mp, cur->bc_private.a.agno,
&rcext, agbno);
/* Establish the right extent. */
tmp = rcext;
tmp.rc_startblock = agbno;
tmp.rc_blockcount -= (agbno - rcext.rc_startblock);
error = xfs_refcount_update(cur, &tmp);
if (error)
goto out_error;
/* Insert the left extent. */
tmp = rcext;
tmp.rc_blockcount = agbno - rcext.rc_startblock;
error = xfs_refcount_insert(cur, &tmp, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
return error;
out_error:
trace_xfs_refcount_split_extent_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/*
* Merge the left, center, and right extents.
*/
STATIC int
xfs_refcount_merge_center_extents(
struct xfs_btree_cur *cur,
struct xfs_refcount_irec *left,
struct xfs_refcount_irec *center,
struct xfs_refcount_irec *right,
unsigned long long extlen,
xfs_agblock_t *agbno,
xfs_extlen_t *aglen)
{
int error;
int found_rec;
trace_xfs_refcount_merge_center_extents(cur->bc_mp,
cur->bc_private.a.agno, left, center, right);
/*
* Make sure the center and right extents are not in the btree.
* If the center extent was synthesized, the first delete call
* removes the right extent and we skip the second deletion.
* If center and right were in the btree, then the first delete
* call removes the center and the second one removes the right
* extent.
*/
error = xfs_refcount_lookup_ge(cur, center->rc_startblock,
&found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
if (center->rc_refcount > 1) {
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
out_error);
}
/* Enlarge the left extent. */
error = xfs_refcount_lookup_le(cur, left->rc_startblock,
&found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
left->rc_blockcount = extlen;
error = xfs_refcount_update(cur, left);
if (error)
goto out_error;
*aglen = 0;
return error;
out_error:
trace_xfs_refcount_merge_center_extents_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/*
* Merge with the left extent.
*/
STATIC int
xfs_refcount_merge_left_extent(
struct xfs_btree_cur *cur,
struct xfs_refcount_irec *left,
struct xfs_refcount_irec *cleft,
xfs_agblock_t *agbno,
xfs_extlen_t *aglen)
{
int error;
int found_rec;
trace_xfs_refcount_merge_left_extent(cur->bc_mp,
cur->bc_private.a.agno, left, cleft);
/* If the extent at agbno (cleft) wasn't synthesized, remove it. */
if (cleft->rc_refcount > 1) {
error = xfs_refcount_lookup_le(cur, cleft->rc_startblock,
&found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
out_error);
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
out_error);
}
/* Enlarge the left extent. */
error = xfs_refcount_lookup_le(cur, left->rc_startblock,
&found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
left->rc_blockcount += cleft->rc_blockcount;
error = xfs_refcount_update(cur, left);
if (error)
goto out_error;
*agbno += cleft->rc_blockcount;
*aglen -= cleft->rc_blockcount;
return error;
out_error:
trace_xfs_refcount_merge_left_extent_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/*
* Merge with the right extent.
*/
STATIC int
xfs_refcount_merge_right_extent(
struct xfs_btree_cur *cur,
struct xfs_refcount_irec *right,
struct xfs_refcount_irec *cright,
xfs_agblock_t *agbno,
xfs_extlen_t *aglen)
{
int error;
int found_rec;
trace_xfs_refcount_merge_right_extent(cur->bc_mp,
cur->bc_private.a.agno, cright, right);
/*
* If the extent ending at agbno+aglen (cright) wasn't synthesized,
* remove it.
*/
if (cright->rc_refcount > 1) {
error = xfs_refcount_lookup_le(cur, cright->rc_startblock,
&found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
out_error);
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
out_error);
}
/* Enlarge the right extent. */
error = xfs_refcount_lookup_le(cur, right->rc_startblock,
&found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
right->rc_startblock -= cright->rc_blockcount;
right->rc_blockcount += cright->rc_blockcount;
error = xfs_refcount_update(cur, right);
if (error)
goto out_error;
*aglen -= cright->rc_blockcount;
return error;
out_error:
trace_xfs_refcount_merge_right_extent_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
#define XFS_FIND_RCEXT_SHARED 1
#define XFS_FIND_RCEXT_COW 2
/*
* Find the left extent and the one after it (cleft). This function assumes
* that we've already split any extent crossing agbno.
*/
STATIC int
xfs_refcount_find_left_extents(
struct xfs_btree_cur *cur,
struct xfs_refcount_irec *left,
struct xfs_refcount_irec *cleft,
xfs_agblock_t agbno,
xfs_extlen_t aglen,
int flags)
{
struct xfs_refcount_irec tmp;
int error;
int found_rec;
left->rc_startblock = cleft->rc_startblock = NULLAGBLOCK;
error = xfs_refcount_lookup_le(cur, agbno - 1, &found_rec);
if (error)
goto out_error;
if (!found_rec)
return 0;
error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
if (xfs_refc_next(&tmp) != agbno)
return 0;
if ((flags & XFS_FIND_RCEXT_SHARED) && tmp.rc_refcount < 2)
return 0;
if ((flags & XFS_FIND_RCEXT_COW) && tmp.rc_refcount > 1)
return 0;
/* We have a left extent; retrieve (or invent) the next right one */
*left = tmp;
error = xfs_btree_increment(cur, 0, &found_rec);
if (error)
goto out_error;
if (found_rec) {
error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
out_error);
/* if tmp starts at the end of our range, just use that */
if (tmp.rc_startblock == agbno)
*cleft = tmp;
else {
/*
* There's a gap in the refcntbt at the start of the
* range we're interested in (refcount == 1) so
* synthesize the implied extent and pass it back.
* We assume here that the agbno/aglen range was
* passed in from a data fork extent mapping and
* therefore is allocated to exactly one owner.
*/
cleft->rc_startblock = agbno;
cleft->rc_blockcount = min(aglen,
tmp.rc_startblock - agbno);
cleft->rc_refcount = 1;
}
} else {
/*
* No extents, so pretend that there's one covering the whole
* range.
*/
cleft->rc_startblock = agbno;
cleft->rc_blockcount = aglen;
cleft->rc_refcount = 1;
}
trace_xfs_refcount_find_left_extent(cur->bc_mp, cur->bc_private.a.agno,
left, cleft, agbno);
return error;
out_error:
trace_xfs_refcount_find_left_extent_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/*
* Find the right extent and the one before it (cright). This function
* assumes that we've already split any extents crossing agbno + aglen.
*/
STATIC int
xfs_refcount_find_right_extents(
struct xfs_btree_cur *cur,
struct xfs_refcount_irec *right,
struct xfs_refcount_irec *cright,
xfs_agblock_t agbno,
xfs_extlen_t aglen,
int flags)
{
struct xfs_refcount_irec tmp;
int error;
int found_rec;
right->rc_startblock = cright->rc_startblock = NULLAGBLOCK;
error = xfs_refcount_lookup_ge(cur, agbno + aglen, &found_rec);
if (error)
goto out_error;
if (!found_rec)
return 0;
error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
if (tmp.rc_startblock != agbno + aglen)
return 0;
if ((flags & XFS_FIND_RCEXT_SHARED) && tmp.rc_refcount < 2)
return 0;
if ((flags & XFS_FIND_RCEXT_COW) && tmp.rc_refcount > 1)
return 0;
/* We have a right extent; retrieve (or invent) the next left one */
*right = tmp;
error = xfs_btree_decrement(cur, 0, &found_rec);
if (error)
goto out_error;
if (found_rec) {
error = xfs_refcount_get_rec(cur, &tmp, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
out_error);
/* if tmp ends at the end of our range, just use that */
if (xfs_refc_next(&tmp) == agbno + aglen)
*cright = tmp;
else {
/*
* There's a gap in the refcntbt at the end of the
* range we're interested in (refcount == 1) so
* create the implied extent and pass it back.
* We assume here that the agbno/aglen range was
* passed in from a data fork extent mapping and
* therefore is allocated to exactly one owner.
*/
cright->rc_startblock = max(agbno, xfs_refc_next(&tmp));
cright->rc_blockcount = right->rc_startblock -
cright->rc_startblock;
cright->rc_refcount = 1;
}
} else {
/*
* No extents, so pretend that there's one covering the whole
* range.
*/
cright->rc_startblock = agbno;
cright->rc_blockcount = aglen;
cright->rc_refcount = 1;
}
trace_xfs_refcount_find_right_extent(cur->bc_mp, cur->bc_private.a.agno,
cright, right, agbno + aglen);
return error;
out_error:
trace_xfs_refcount_find_right_extent_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/* Is this extent valid? */
static inline bool
xfs_refc_valid(
struct xfs_refcount_irec *rc)
{
return rc->rc_startblock != NULLAGBLOCK;
}
/*
* Try to merge with any extents on the boundaries of the adjustment range.
*/
STATIC int
xfs_refcount_merge_extents(
struct xfs_btree_cur *cur,
xfs_agblock_t *agbno,
xfs_extlen_t *aglen,
enum xfs_refc_adjust_op adjust,
int flags,
bool *shape_changed)
{
struct xfs_refcount_irec left = {0}, cleft = {0};
struct xfs_refcount_irec cright = {0}, right = {0};
int error;
unsigned long long ulen;
bool cequal;
*shape_changed = false;
/*
* Find the extent just below agbno [left], just above agbno [cleft],
* just below (agbno + aglen) [cright], and just above (agbno + aglen)
* [right].
*/
error = xfs_refcount_find_left_extents(cur, &left, &cleft, *agbno,
*aglen, flags);
if (error)
return error;
error = xfs_refcount_find_right_extents(cur, &right, &cright, *agbno,
*aglen, flags);
if (error)
return error;
/* No left or right extent to merge; exit. */
if (!xfs_refc_valid(&left) && !xfs_refc_valid(&right))
return 0;
cequal = (cleft.rc_startblock == cright.rc_startblock) &&
(cleft.rc_blockcount == cright.rc_blockcount);
/* Try to merge left, cleft, and right. cleft must == cright. */
ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount +
right.rc_blockcount;
if (xfs_refc_valid(&left) && xfs_refc_valid(&right) &&
xfs_refc_valid(&cleft) && xfs_refc_valid(&cright) && cequal &&
left.rc_refcount == cleft.rc_refcount + adjust &&
right.rc_refcount == cleft.rc_refcount + adjust &&
ulen < MAXREFCEXTLEN) {
*shape_changed = true;
return xfs_refcount_merge_center_extents(cur, &left, &cleft,
&right, ulen, agbno, aglen);
}
/* Try to merge left and cleft. */
ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount;
if (xfs_refc_valid(&left) && xfs_refc_valid(&cleft) &&
left.rc_refcount == cleft.rc_refcount + adjust &&
ulen < MAXREFCEXTLEN) {
*shape_changed = true;
error = xfs_refcount_merge_left_extent(cur, &left, &cleft,
agbno, aglen);
if (error)
return error;
/*
* If we just merged left + cleft and cleft == cright,
* we no longer have a cright to merge with right. We're done.
*/
if (cequal)
return 0;
}
/* Try to merge cright and right. */
ulen = (unsigned long long)right.rc_blockcount + cright.rc_blockcount;
if (xfs_refc_valid(&right) && xfs_refc_valid(&cright) &&
right.rc_refcount == cright.rc_refcount + adjust &&
ulen < MAXREFCEXTLEN) {
*shape_changed = true;
return xfs_refcount_merge_right_extent(cur, &right, &cright,
agbno, aglen);
}
return error;
}
/*
* XXX: This is a pretty hand-wavy estimate. The penalty for guessing
* true incorrectly is a shutdown FS; the penalty for guessing false
* incorrectly is more transaction rolls than might be necessary.
* Be conservative here.
*/
static bool
xfs_refcount_still_have_space(
struct xfs_btree_cur *cur)
{
unsigned long overhead;
overhead = cur->bc_private.a.priv.refc.shape_changes *
xfs_allocfree_log_count(cur->bc_mp, 1);
overhead *= cur->bc_mp->m_sb.sb_blocksize;
/*
* Only allow 2 refcount extent updates per transaction if the
* refcount continue update "error" has been injected.
*/
if (cur->bc_private.a.priv.refc.nr_ops > 2 &&
XFS_TEST_ERROR(false, cur->bc_mp,
XFS_ERRTAG_REFCOUNT_CONTINUE_UPDATE,
XFS_RANDOM_REFCOUNT_CONTINUE_UPDATE))
return false;
if (cur->bc_private.a.priv.refc.nr_ops == 0)
return true;
else if (overhead > cur->bc_tp->t_log_res)
return false;
return cur->bc_tp->t_log_res - overhead >
cur->bc_private.a.priv.refc.nr_ops * XFS_REFCOUNT_ITEM_OVERHEAD;
}
/*
* Adjust the refcounts of middle extents. At this point we should have
* split extents that crossed the adjustment range; merged with adjacent
* extents; and updated agbno/aglen to reflect the merges. Therefore,
* all we have to do is update the extents inside [agbno, agbno + aglen].
*/
STATIC int
xfs_refcount_adjust_extents(
struct xfs_btree_cur *cur,
xfs_agblock_t *agbno,
xfs_extlen_t *aglen,
enum xfs_refc_adjust_op adj,
struct xfs_defer_ops *dfops,
struct xfs_owner_info *oinfo)
{
struct xfs_refcount_irec ext, tmp;
int error;
int found_rec, found_tmp;
xfs_fsblock_t fsbno;
/* Merging did all the work already. */
if (*aglen == 0)
return 0;
error = xfs_refcount_lookup_ge(cur, *agbno, &found_rec);
if (error)
goto out_error;
while (*aglen > 0 && xfs_refcount_still_have_space(cur)) {
error = xfs_refcount_get_rec(cur, &ext, &found_rec);
if (error)
goto out_error;
if (!found_rec) {
ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
ext.rc_blockcount = 0;
ext.rc_refcount = 0;
}
/*
* Deal with a hole in the refcount tree; if a file maps to
* these blocks and there's no refcountbt record, pretend that
* there is one with refcount == 1.
*/
if (ext.rc_startblock != *agbno) {
tmp.rc_startblock = *agbno;
tmp.rc_blockcount = min(*aglen,
ext.rc_startblock - *agbno);
tmp.rc_refcount = 1 + adj;
trace_xfs_refcount_modify_extent(cur->bc_mp,
cur->bc_private.a.agno, &tmp);
/*
* Either cover the hole (increment) or
* delete the range (decrement).
*/
if (tmp.rc_refcount) {
error = xfs_refcount_insert(cur, &tmp,
&found_tmp);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
found_tmp == 1, out_error);
cur->bc_private.a.priv.refc.nr_ops++;
} else {
fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
cur->bc_private.a.agno,
tmp.rc_startblock);
xfs_bmap_add_free(cur->bc_mp, dfops, fsbno,
tmp.rc_blockcount, oinfo);
}
(*agbno) += tmp.rc_blockcount;
(*aglen) -= tmp.rc_blockcount;
error = xfs_refcount_lookup_ge(cur, *agbno,
&found_rec);
if (error)
goto out_error;
}
/* Stop if there's nothing left to modify */
if (*aglen == 0 || !xfs_refcount_still_have_space(cur))
break;
/*
* Adjust the reference count and either update the tree
* (incr) or free the blocks (decr).
*/
if (ext.rc_refcount == MAXREFCOUNT)
goto skip;
ext.rc_refcount += adj;
trace_xfs_refcount_modify_extent(cur->bc_mp,
cur->bc_private.a.agno, &ext);
if (ext.rc_refcount > 1) {
error = xfs_refcount_update(cur, &ext);
if (error)
goto out_error;
cur->bc_private.a.priv.refc.nr_ops++;
} else if (ext.rc_refcount == 1) {
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
found_rec == 1, out_error);
cur->bc_private.a.priv.refc.nr_ops++;
goto advloop;
} else {
fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
cur->bc_private.a.agno,
ext.rc_startblock);
xfs_bmap_add_free(cur->bc_mp, dfops, fsbno,
ext.rc_blockcount, oinfo);
}
skip:
error = xfs_btree_increment(cur, 0, &found_rec);
if (error)
goto out_error;
advloop:
(*agbno) += ext.rc_blockcount;
(*aglen) -= ext.rc_blockcount;
}
return error;
out_error:
trace_xfs_refcount_modify_extent_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/* Adjust the reference count of a range of AG blocks. */
STATIC int
xfs_refcount_adjust(
struct xfs_btree_cur *cur,
xfs_agblock_t agbno,
xfs_extlen_t aglen,
xfs_agblock_t *new_agbno,
xfs_extlen_t *new_aglen,
enum xfs_refc_adjust_op adj,
struct xfs_defer_ops *dfops,
struct xfs_owner_info *oinfo)
{
bool shape_changed;
int shape_changes = 0;
int error;
*new_agbno = agbno;
*new_aglen = aglen;
if (adj == XFS_REFCOUNT_ADJUST_INCREASE)
trace_xfs_refcount_increase(cur->bc_mp, cur->bc_private.a.agno,
agbno, aglen);
else
trace_xfs_refcount_decrease(cur->bc_mp, cur->bc_private.a.agno,
agbno, aglen);
/*
* Ensure that no rcextents cross the boundary of the adjustment range.
*/
error = xfs_refcount_split_extent(cur, agbno, &shape_changed);
if (error)
goto out_error;
if (shape_changed)
shape_changes++;
error = xfs_refcount_split_extent(cur, agbno + aglen, &shape_changed);
if (error)
goto out_error;
if (shape_changed)
shape_changes++;
/*
* Try to merge with the left or right extents of the range.
*/
error = xfs_refcount_merge_extents(cur, new_agbno, new_aglen, adj,
XFS_FIND_RCEXT_SHARED, &shape_changed);
if (error)
goto out_error;
if (shape_changed)
shape_changes++;
if (shape_changes)
cur->bc_private.a.priv.refc.shape_changes++;
/* Now that we've taken care of the ends, adjust the middle extents */
error = xfs_refcount_adjust_extents(cur, new_agbno, new_aglen,
adj, dfops, oinfo);
if (error)
goto out_error;
return 0;
out_error:
trace_xfs_refcount_adjust_error(cur->bc_mp, cur->bc_private.a.agno,
error, _RET_IP_);
return error;
}
/* Clean up after calling xfs_refcount_finish_one. */
void
xfs_refcount_finish_one_cleanup(
struct xfs_trans *tp,
struct xfs_btree_cur *rcur,
int error)
{
struct xfs_buf *agbp;
if (rcur == NULL)
return;
agbp = rcur->bc_private.a.agbp;
xfs_btree_del_cursor(rcur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
if (error)
xfs_trans_brelse(tp, agbp);
}
/*
* Process one of the deferred refcount operations. We pass back the
* btree cursor to maintain our lock on the btree between calls.
* This saves time and eliminates a buffer deadlock between the
* superblock and the AGF because we'll always grab them in the same
* order.
*/
int
xfs_refcount_finish_one(
struct xfs_trans *tp,
struct xfs_defer_ops *dfops,
enum xfs_refcount_intent_type type,
xfs_fsblock_t startblock,
xfs_extlen_t blockcount,
xfs_fsblock_t *new_fsb,
xfs_extlen_t *new_len,
struct xfs_btree_cur **pcur)
{
struct xfs_mount *mp = tp->t_mountp;
struct xfs_btree_cur *rcur;
struct xfs_buf *agbp = NULL;
int error = 0;
xfs_agnumber_t agno;
xfs_agblock_t bno;
xfs_agblock_t new_agbno;
unsigned long nr_ops = 0;
int shape_changes = 0;
agno = XFS_FSB_TO_AGNO(mp, startblock);
ASSERT(agno != NULLAGNUMBER);
bno = XFS_FSB_TO_AGBNO(mp, startblock);
trace_xfs_refcount_deferred(mp, XFS_FSB_TO_AGNO(mp, startblock),
type, XFS_FSB_TO_AGBNO(mp, startblock),
blockcount);
if (XFS_TEST_ERROR(false, mp,
XFS_ERRTAG_REFCOUNT_FINISH_ONE,
XFS_RANDOM_REFCOUNT_FINISH_ONE))
return -EIO;
/*
* If we haven't gotten a cursor or the cursor AG doesn't match
* the startblock, get one now.
*/
rcur = *pcur;
if (rcur != NULL && rcur->bc_private.a.agno != agno) {
nr_ops = rcur->bc_private.a.priv.refc.nr_ops;
shape_changes = rcur->bc_private.a.priv.refc.shape_changes;
xfs_refcount_finish_one_cleanup(tp, rcur, 0);
rcur = NULL;
*pcur = NULL;
}
if (rcur == NULL) {
error = xfs_alloc_read_agf(tp->t_mountp, tp, agno,
XFS_ALLOC_FLAG_FREEING, &agbp);
if (error)
return error;
if (!agbp)
return -EFSCORRUPTED;
rcur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, dfops);
if (!rcur) {
error = -ENOMEM;
goto out_cur;
}
rcur->bc_private.a.priv.refc.nr_ops = nr_ops;
rcur->bc_private.a.priv.refc.shape_changes = shape_changes;
}
*pcur = rcur;
switch (type) {
case XFS_REFCOUNT_INCREASE:
error = xfs_refcount_adjust(rcur, bno, blockcount, &new_agbno,
new_len, XFS_REFCOUNT_ADJUST_INCREASE, dfops, NULL);
*new_fsb = XFS_AGB_TO_FSB(mp, agno, new_agbno);
break;
case XFS_REFCOUNT_DECREASE:
error = xfs_refcount_adjust(rcur, bno, blockcount, &new_agbno,
new_len, XFS_REFCOUNT_ADJUST_DECREASE, dfops, NULL);
*new_fsb = XFS_AGB_TO_FSB(mp, agno, new_agbno);
break;
case XFS_REFCOUNT_ALLOC_COW:
*new_fsb = startblock + blockcount;
*new_len = 0;
error = __xfs_refcount_cow_alloc(rcur, bno, blockcount, dfops);
break;
case XFS_REFCOUNT_FREE_COW:
*new_fsb = startblock + blockcount;
*new_len = 0;
error = __xfs_refcount_cow_free(rcur, bno, blockcount, dfops);
break;
default:
ASSERT(0);
error = -EFSCORRUPTED;
}
if (!error && *new_len > 0)
trace_xfs_refcount_finish_one_leftover(mp, agno, type,
bno, blockcount, new_agbno, *new_len);
return error;
out_cur:
xfs_trans_brelse(tp, agbp);
return error;
}
/*
* Record a refcount intent for later processing.
*/
static int
__xfs_refcount_add(
struct xfs_mount *mp,
struct xfs_defer_ops *dfops,
enum xfs_refcount_intent_type type,
xfs_fsblock_t startblock,
xfs_extlen_t blockcount)
{
struct xfs_refcount_intent *ri;
trace_xfs_refcount_defer(mp, XFS_FSB_TO_AGNO(mp, startblock),
type, XFS_FSB_TO_AGBNO(mp, startblock),
blockcount);
ri = kmem_alloc(sizeof(struct xfs_refcount_intent),
KM_SLEEP | KM_NOFS);
INIT_LIST_HEAD(&ri->ri_list);
ri->ri_type = type;
ri->ri_startblock = startblock;
ri->ri_blockcount = blockcount;
xfs_defer_add(dfops, XFS_DEFER_OPS_TYPE_REFCOUNT, &ri->ri_list);
return 0;
}
/*
* Increase the reference count of the blocks backing a file's extent.
*/
int
xfs_refcount_increase_extent(
struct xfs_mount *mp,
struct xfs_defer_ops *dfops,
struct xfs_bmbt_irec *PREV)
{
if (!xfs_sb_version_hasreflink(&mp->m_sb))
return 0;
return __xfs_refcount_add(mp, dfops, XFS_REFCOUNT_INCREASE,
PREV->br_startblock, PREV->br_blockcount);
}
/*
* Decrease the reference count of the blocks backing a file's extent.
*/
int
xfs_refcount_decrease_extent(
struct xfs_mount *mp,
struct xfs_defer_ops *dfops,
struct xfs_bmbt_irec *PREV)
{
if (!xfs_sb_version_hasreflink(&mp->m_sb))
return 0;
return __xfs_refcount_add(mp, dfops, XFS_REFCOUNT_DECREASE,
PREV->br_startblock, PREV->br_blockcount);
}
/*
* 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 set, return the longest contiguous extent of
* shared blocks; if not, just return the first extent we find. If no
* shared blocks are found, fbno and flen will be set to NULLAGBLOCK
* and 0, respectively.
*/
int
xfs_refcount_find_shared(
struct xfs_btree_cur *cur,
xfs_agblock_t agbno,
xfs_extlen_t aglen,
xfs_agblock_t *fbno,
xfs_extlen_t *flen,
bool find_end_of_shared)
{
struct xfs_refcount_irec tmp;
int i;
int have;
int error;
trace_xfs_refcount_find_shared(cur->bc_mp, cur->bc_private.a.agno,
agbno, aglen);
/* By default, skip the whole range */
*fbno = NULLAGBLOCK;
*flen = 0;
/* Try to find a refcount extent that crosses the start */
error = xfs_refcount_lookup_le(cur, agbno, &have);
if (error)
goto out_error;
if (!have) {
/* No left extent, look at the next one */
error = xfs_btree_increment(cur, 0, &have);
if (error)
goto out_error;
if (!have)
goto done;
}
error = xfs_refcount_get_rec(cur, &tmp, &i);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, out_error);
/* If the extent ends before the start, look at the next one */
if (tmp.rc_startblock + tmp.rc_blockcount <= agbno) {
error = xfs_btree_increment(cur, 0, &have);
if (error)
goto out_error;
if (!have)
goto done;
error = xfs_refcount_get_rec(cur, &tmp, &i);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, out_error);
}
/* If the extent starts after the range we want, bail out */
if (tmp.rc_startblock >= agbno + aglen)
goto done;
/* We found the start of a shared extent! */
if (tmp.rc_startblock < agbno) {
tmp.rc_blockcount -= (agbno - tmp.rc_startblock);
tmp.rc_startblock = agbno;
}
*fbno = tmp.rc_startblock;
*flen = min(tmp.rc_blockcount, agbno + aglen - *fbno);
if (!find_end_of_shared)
goto done;
/* Otherwise, find the end of this shared extent */
while (*fbno + *flen < agbno + aglen) {
error = xfs_btree_increment(cur, 0, &have);
if (error)
goto out_error;
if (!have)
break;
error = xfs_refcount_get_rec(cur, &tmp, &i);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, i == 1, out_error);
if (tmp.rc_startblock >= agbno + aglen ||
tmp.rc_startblock != *fbno + *flen)
break;
*flen = min(*flen + tmp.rc_blockcount, agbno + aglen - *fbno);
}
done:
trace_xfs_refcount_find_shared_result(cur->bc_mp,
cur->bc_private.a.agno, *fbno, *flen);
out_error:
if (error)
trace_xfs_refcount_find_shared_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/*
* Recovering CoW Blocks After a Crash
*
* Due to the way that the copy on write mechanism works, there's a window of
* opportunity in which we can lose track of allocated blocks during a crash.
* Because CoW uses delayed allocation in the in-core CoW fork, writeback
* causes blocks to be allocated and stored in the CoW fork. The blocks are
* no longer in the free space btree but are not otherwise recorded anywhere
* until the write completes and the blocks are mapped into the file. A crash
* in between allocation and remapping results in the replacement blocks being
* lost. This situation is exacerbated by the CoW extent size hint because
* allocations can hang around for long time.
*
* However, there is a place where we can record these allocations before they
* become mappings -- the reference count btree. The btree does not record
* extents with refcount == 1, so we can record allocations with a refcount of
* 1. Blocks being used for CoW writeout cannot be shared, so there should be
* no conflict with shared block records. These mappings should be created
* when we allocate blocks to the CoW fork and deleted when they're removed
* from the CoW fork.
*
* Minor nit: records for in-progress CoW allocations and records for shared
* extents must never be merged, to preserve the property that (except for CoW
* allocations) there are no refcount btree entries with refcount == 1. The
* only time this could potentially happen is when unsharing a block that's
* adjacent to CoW allocations, so we must be careful to avoid this.
*
* At mount time we recover lost CoW allocations by searching the refcount
* btree for these refcount == 1 mappings. These represent CoW allocations
* that were in progress at the time the filesystem went down, so we can free
* them to get the space back.
*
* This mechanism is superior to creating EFIs for unmapped CoW extents for
* several reasons -- first, EFIs pin the tail of the log and would have to be
* periodically relogged to avoid filling up the log. Second, CoW completions
* will have to file an EFD and create new EFIs for whatever remains in the
* CoW fork; this partially takes care of (1) but extent-size reservations
* will have to periodically relog even if there's no writeout in progress.
* This can happen if the CoW extent size hint is set, which you really want.
* Third, EFIs cannot currently be automatically relogged into newer
* transactions to advance the log tail. Fourth, stuffing the log full of
* EFIs places an upper bound on the number of CoW allocations that can be
* held filesystem-wide at any given time. Recording them in the refcount
* btree doesn't require us to maintain any state in memory and doesn't pin
* the log.
*/
/*
* Adjust the refcounts of CoW allocations. These allocations are "magic"
* in that they're not referenced anywhere else in the filesystem, so we
* stash them in the refcount btree with a refcount of 1 until either file
* remapping (or CoW cancellation) happens.
*/
STATIC int
xfs_refcount_adjust_cow_extents(
struct xfs_btree_cur *cur,
xfs_agblock_t agbno,
xfs_extlen_t aglen,
enum xfs_refc_adjust_op adj,
struct xfs_defer_ops *dfops,
struct xfs_owner_info *oinfo)
{
struct xfs_refcount_irec ext, tmp;
int error;
int found_rec, found_tmp;
if (aglen == 0)
return 0;
/* Find any overlapping refcount records */
error = xfs_refcount_lookup_ge(cur, agbno, &found_rec);
if (error)
goto out_error;
error = xfs_refcount_get_rec(cur, &ext, &found_rec);
if (error)
goto out_error;
if (!found_rec) {
ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks +
XFS_REFC_COW_START;
ext.rc_blockcount = 0;
ext.rc_refcount = 0;
}
switch (adj) {
case XFS_REFCOUNT_ADJUST_COW_ALLOC:
/* Adding a CoW reservation, there should be nothing here. */
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
ext.rc_startblock >= agbno + aglen, out_error);
tmp.rc_startblock = agbno;
tmp.rc_blockcount = aglen;
tmp.rc_refcount = 1;
trace_xfs_refcount_modify_extent(cur->bc_mp,
cur->bc_private.a.agno, &tmp);
error = xfs_refcount_insert(cur, &tmp,
&found_tmp);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
found_tmp == 1, out_error);
break;
case XFS_REFCOUNT_ADJUST_COW_FREE:
/* Removing a CoW reservation, there should be one extent. */
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
ext.rc_startblock == agbno, out_error);
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
ext.rc_blockcount == aglen, out_error);
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
ext.rc_refcount == 1, out_error);
ext.rc_refcount = 0;
trace_xfs_refcount_modify_extent(cur->bc_mp,
cur->bc_private.a.agno, &ext);
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
found_rec == 1, out_error);
break;
default:
ASSERT(0);
}
return error;
out_error:
trace_xfs_refcount_modify_extent_error(cur->bc_mp,
cur->bc_private.a.agno, error, _RET_IP_);
return error;
}
/*
* Add or remove refcount btree entries for CoW reservations.
*/
STATIC int
xfs_refcount_adjust_cow(
struct xfs_btree_cur *cur,
xfs_agblock_t agbno,
xfs_extlen_t aglen,
enum xfs_refc_adjust_op adj,
struct xfs_defer_ops *dfops)
{
bool shape_changed;
int error;
agbno += XFS_REFC_COW_START;
/*
* Ensure that no rcextents cross the boundary of the adjustment range.
*/
error = xfs_refcount_split_extent(cur, agbno, &shape_changed);
if (error)
goto out_error;
error = xfs_refcount_split_extent(cur, agbno + aglen, &shape_changed);
if (error)
goto out_error;
/*
* Try to merge with the left or right extents of the range.
*/
error = xfs_refcount_merge_extents(cur, &agbno, &aglen, adj,
XFS_FIND_RCEXT_COW, &shape_changed);
if (error)
goto out_error;
/* Now that we've taken care of the ends, adjust the middle extents */
error = xfs_refcount_adjust_cow_extents(cur, agbno, aglen, adj,
dfops, NULL);
if (error)
goto out_error;
return 0;
out_error:
trace_xfs_refcount_adjust_cow_error(cur->bc_mp, cur->bc_private.a.agno,
error, _RET_IP_);
return error;
}
/*
* Record a CoW allocation in the refcount btree.
*/
STATIC int
__xfs_refcount_cow_alloc(
struct xfs_btree_cur *rcur,
xfs_agblock_t agbno,
xfs_extlen_t aglen,
struct xfs_defer_ops *dfops)
{
int error;
trace_xfs_refcount_cow_increase(rcur->bc_mp, rcur->bc_private.a.agno,
agbno, aglen);
/* Add refcount btree reservation */
error = xfs_refcount_adjust_cow(rcur, agbno, aglen,
XFS_REFCOUNT_ADJUST_COW_ALLOC, dfops);
if (error)
return error;
/* Add rmap entry */
if (xfs_sb_version_hasrmapbt(&rcur->bc_mp->m_sb)) {
error = xfs_rmap_alloc_extent(rcur->bc_mp, dfops,
rcur->bc_private.a.agno,
agbno, aglen, XFS_RMAP_OWN_COW);
if (error)
return error;
}
return error;
}
/*
* Remove a CoW allocation from the refcount btree.
*/
STATIC int
__xfs_refcount_cow_free(
struct xfs_btree_cur *rcur,
xfs_agblock_t agbno,
xfs_extlen_t aglen,
struct xfs_defer_ops *dfops)
{
int error;
trace_xfs_refcount_cow_decrease(rcur->bc_mp, rcur->bc_private.a.agno,
agbno, aglen);
/* Remove refcount btree reservation */
error = xfs_refcount_adjust_cow(rcur, agbno, aglen,
XFS_REFCOUNT_ADJUST_COW_FREE, dfops);
if (error)
return error;
/* Remove rmap entry */
if (xfs_sb_version_hasrmapbt(&rcur->bc_mp->m_sb)) {
error = xfs_rmap_free_extent(rcur->bc_mp, dfops,
rcur->bc_private.a.agno,
agbno, aglen, XFS_RMAP_OWN_COW);
if (error)
return error;
}
return error;
}
/* Record a CoW staging extent in the refcount btree. */
int
xfs_refcount_alloc_cow_extent(
struct xfs_mount *mp,
struct xfs_defer_ops *dfops,
xfs_fsblock_t fsb,
xfs_extlen_t len)
{
if (!xfs_sb_version_hasreflink(&mp->m_sb))
return 0;
return __xfs_refcount_add(mp, dfops, XFS_REFCOUNT_ALLOC_COW,
fsb, len);
}
/* Forget a CoW staging event in the refcount btree. */
int
xfs_refcount_free_cow_extent(
struct xfs_mount *mp,
struct xfs_defer_ops *dfops,
xfs_fsblock_t fsb,
xfs_extlen_t len)
{
if (!xfs_sb_version_hasreflink(&mp->m_sb))
return 0;
return __xfs_refcount_add(mp, dfops, XFS_REFCOUNT_FREE_COW,
fsb, len);
}
struct xfs_refcount_recovery {
struct list_head rr_list;
struct xfs_refcount_irec rr_rrec;
};
/* Stuff an extent on the recovery list. */
STATIC int
xfs_refcount_recover_extent(
struct xfs_btree_cur *cur,
union xfs_btree_rec *rec,
void *priv)
{
struct list_head *debris = priv;
struct xfs_refcount_recovery *rr;
if (be32_to_cpu(rec->refc.rc_refcount) != 1)
return -EFSCORRUPTED;
rr = kmem_alloc(sizeof(struct xfs_refcount_recovery), KM_SLEEP);
xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
list_add_tail(&rr->rr_list, debris);
return 0;
}
/* Find and remove leftover CoW reservations. */
int
xfs_refcount_recover_cow_leftovers(
struct xfs_mount *mp,
xfs_agnumber_t agno)
{
struct xfs_trans *tp;
struct xfs_btree_cur *cur;
struct xfs_buf *agbp;
struct xfs_refcount_recovery *rr, *n;
struct list_head debris;
union xfs_btree_irec low;
union xfs_btree_irec high;
struct xfs_defer_ops dfops;
xfs_fsblock_t fsb;
xfs_agblock_t agbno;
int error;
if (mp->m_sb.sb_agblocks >= XFS_REFC_COW_START)
return -EOPNOTSUPP;
INIT_LIST_HEAD(&debris);
/*
* In this first part, we use an empty transaction to gather up
* all the leftover CoW extents so that we can subsequently
* delete them. The empty transaction is used to avoid
* a buffer lock deadlock if there happens to be a loop in the
* refcountbt because we're allowed to re-grab a buffer that is
* already attached to our transaction. When we're done
* recording the CoW debris we cancel the (empty) transaction
* and everything goes away cleanly.
*/
error = xfs_trans_alloc_empty(mp, &tp);
if (error)
return error;
error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
if (error)
goto out_trans;
cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL);
/* Find all the leftover CoW staging extents. */
memset(&low, 0, sizeof(low));
memset(&high, 0, sizeof(high));
low.rc.rc_startblock = XFS_REFC_COW_START;
high.rc.rc_startblock = -1U;
error = xfs_btree_query_range(cur, &low, &high,
xfs_refcount_recover_extent, &debris);
if (error)
goto out_cursor;
xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
xfs_trans_brelse(tp, agbp);
xfs_trans_cancel(tp);
/* Now iterate the list to free the leftovers */
list_for_each_entry_safe(rr, n, &debris, rr_list) {
/* Set up transaction. */
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
if (error)
goto out_free;
trace_xfs_refcount_recover_extent(mp, agno, &rr->rr_rrec);
/* Free the orphan record */
xfs_defer_init(&dfops, &fsb);
agbno = rr->rr_rrec.rc_startblock - XFS_REFC_COW_START;
fsb = XFS_AGB_TO_FSB(mp, agno, agbno);
error = xfs_refcount_free_cow_extent(mp, &dfops, fsb,
rr->rr_rrec.rc_blockcount);
if (error)
goto out_defer;
/* Free the block. */
xfs_bmap_add_free(mp, &dfops, fsb,
rr->rr_rrec.rc_blockcount, NULL);
error = xfs_defer_finish(&tp, &dfops, NULL);
if (error)
goto out_defer;
error = xfs_trans_commit(tp);
if (error)
goto out_free;
list_del(&rr->rr_list);
kmem_free(rr);
}
return error;
out_defer:
xfs_defer_cancel(&dfops);
out_trans:
xfs_trans_cancel(tp);
out_free:
/* Free the leftover list */
list_for_each_entry_safe(rr, n, &debris, rr_list) {
list_del(&rr->rr_list);
kmem_free(rr);
}
return error;
out_cursor:
xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
xfs_trans_brelse(tp, agbp);
goto out_trans;
}
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