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linux-zen-server/fs/xfs/libxfs/xfs_refcount.c

2020 lines
53 KiB
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Initial commit
2023-08-30 17:53:23 +02:00
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2016 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <darrick.wong@oracle.com>
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_btree.h"
#include "xfs_bmap.h"
#include "xfs_refcount_btree.h"
#include "xfs_alloc.h"
#include "xfs_errortag.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_trans.h"
#include "xfs_bit.h"
#include "xfs_refcount.h"
#include "xfs_rmap.h"
#include "xfs_ag.h"
struct kmem_cache *xfs_refcount_intent_cache;
/* 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);
STATIC int __xfs_refcount_cow_free(struct xfs_btree_cur *rcur,
xfs_agblock_t agbno, xfs_extlen_t aglen);
/*
* 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,
enum xfs_refc_domain domain,
xfs_agblock_t bno,
int *stat)
{
trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_ag.pag->pag_agno,
xfs_refcount_encode_startblock(bno, domain),
XFS_LOOKUP_LE);
cur->bc_rec.rc.rc_startblock = bno;
cur->bc_rec.rc.rc_blockcount = 0;
cur->bc_rec.rc.rc_domain = domain;
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,
enum xfs_refc_domain domain,
xfs_agblock_t bno,
int *stat)
{
trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_ag.pag->pag_agno,
xfs_refcount_encode_startblock(bno, domain),
XFS_LOOKUP_GE);
cur->bc_rec.rc.rc_startblock = bno;
cur->bc_rec.rc.rc_blockcount = 0;
cur->bc_rec.rc.rc_domain = domain;
return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
}
/*
* Look up the first record equal to [bno, len] in the btree
* given by cur.
*/
int
xfs_refcount_lookup_eq(
struct xfs_btree_cur *cur,
enum xfs_refc_domain domain,
xfs_agblock_t bno,
int *stat)
{
trace_xfs_refcount_lookup(cur->bc_mp, cur->bc_ag.pag->pag_agno,
xfs_refcount_encode_startblock(bno, domain),
XFS_LOOKUP_LE);
cur->bc_rec.rc.rc_startblock = bno;
cur->bc_rec.rc.rc_blockcount = 0;
cur->bc_rec.rc.rc_domain = domain;
return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
}
/* Convert on-disk record to in-core format. */
void
xfs_refcount_btrec_to_irec(
const union xfs_btree_rec *rec,
struct xfs_refcount_irec *irec)
{
uint32_t start;
start = be32_to_cpu(rec->refc.rc_startblock);
if (start & XFS_REFC_COWFLAG) {
start &= ~XFS_REFC_COWFLAG;
irec->rc_domain = XFS_REFC_DOMAIN_COW;
} else {
irec->rc_domain = XFS_REFC_DOMAIN_SHARED;
}
irec->rc_startblock = start;
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)
{
struct xfs_mount *mp = cur->bc_mp;
struct xfs_perag *pag = cur->bc_ag.pag;
union xfs_btree_rec *rec;
int error;
error = xfs_btree_get_rec(cur, &rec, stat);
if (error || !*stat)
return error;
xfs_refcount_btrec_to_irec(rec, irec);
if (irec->rc_blockcount == 0 || irec->rc_blockcount > MAXREFCEXTLEN)
goto out_bad_rec;
if (!xfs_refcount_check_domain(irec))
goto out_bad_rec;
/* check for valid extent range, including overflow */
if (!xfs_verify_agbext(pag, irec->rc_startblock, irec->rc_blockcount))
goto out_bad_rec;
if (irec->rc_refcount == 0 || irec->rc_refcount > MAXREFCOUNT)
goto out_bad_rec;
trace_xfs_refcount_get(cur->bc_mp, pag->pag_agno, irec);
return 0;
out_bad_rec:
xfs_warn(mp,
"Refcount BTree record corruption in AG %d detected!",
pag->pag_agno);
xfs_warn(mp,
"Start block 0x%x, block count 0x%x, references 0x%x",
irec->rc_startblock, irec->rc_blockcount, irec->rc_refcount);
return -EFSCORRUPTED;
}
/*
* 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;
uint32_t start;
int error;
trace_xfs_refcount_update(cur->bc_mp, cur->bc_ag.pag->pag_agno, irec);
start = xfs_refcount_encode_startblock(irec->rc_startblock,
irec->rc_domain);
rec.refc.rc_startblock = cpu_to_be32(start);
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_ag.pag->pag_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.
*/
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_ag.pag->pag_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;
cur->bc_rec.rc.rc_domain = irec->rc_domain;
error = xfs_btree_insert(cur, i);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, *i != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
out_error:
if (error)
trace_xfs_refcount_insert_error(cur->bc_mp,
cur->bc_ag.pag->pag_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;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
trace_xfs_refcount_delete(cur->bc_mp, cur->bc_ag.pag->pag_agno, &irec);
error = xfs_btree_delete(cur, i);
if (XFS_IS_CORRUPT(cur->bc_mp, *i != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (error)
goto out_error;
error = xfs_refcount_lookup_ge(cur, irec.rc_domain, irec.rc_startblock,
&found_rec);
out_error:
if (error)
trace_xfs_refcount_delete_error(cur->bc_mp,
cur->bc_ag.pag->pag_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,
enum xfs_refc_domain domain,
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, domain, 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;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (rcext.rc_domain != domain)
return 0;
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_ag.pag->pag_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;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
return error;
out_error:
trace_xfs_refcount_split_extent_error(cur->bc_mp,
cur->bc_ag.pag->pag_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_extlen_t *aglen)
{
int error;
int found_rec;
trace_xfs_refcount_merge_center_extents(cur->bc_mp,
cur->bc_ag.pag->pag_agno, left, center, right);
ASSERT(left->rc_domain == center->rc_domain);
ASSERT(right->rc_domain == center->rc_domain);
/*
* 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_domain,
center->rc_startblock, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (center->rc_refcount > 1) {
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
}
/* Enlarge the left extent. */
error = xfs_refcount_lookup_le(cur, left->rc_domain,
left->rc_startblock, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto 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_ag.pag->pag_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_ag.pag->pag_agno, left, cleft);
ASSERT(left->rc_domain == cleft->rc_domain);
/* If the extent at agbno (cleft) wasn't synthesized, remove it. */
if (cleft->rc_refcount > 1) {
error = xfs_refcount_lookup_le(cur, cleft->rc_domain,
cleft->rc_startblock, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
}
/* Enlarge the left extent. */
error = xfs_refcount_lookup_le(cur, left->rc_domain,
left->rc_startblock, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto 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_ag.pag->pag_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_extlen_t *aglen)
{
int error;
int found_rec;
trace_xfs_refcount_merge_right_extent(cur->bc_mp,
cur->bc_ag.pag->pag_agno, cright, right);
ASSERT(right->rc_domain == cright->rc_domain);
/*
* 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_domain,
cright->rc_startblock, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
}
/* Enlarge the right extent. */
error = xfs_refcount_lookup_le(cur, right->rc_domain,
right->rc_startblock, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto 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_ag.pag->pag_agno, error, _RET_IP_);
return error;
}
/*
* 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,
enum xfs_refc_domain domain,
xfs_agblock_t agbno,
xfs_extlen_t aglen)
{
struct xfs_refcount_irec tmp;
int error;
int found_rec;
left->rc_startblock = cleft->rc_startblock = NULLAGBLOCK;
error = xfs_refcount_lookup_le(cur, domain, 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;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (tmp.rc_domain != domain)
return 0;
if (xfs_refc_next(&tmp) != agbno)
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;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (tmp.rc_domain != domain)
goto not_found;
/* 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;
cleft->rc_domain = domain;
}
} else {
not_found:
/*
* No extents, so pretend that there's one covering the whole
* range.
*/
cleft->rc_startblock = agbno;
cleft->rc_blockcount = aglen;
cleft->rc_refcount = 1;
cleft->rc_domain = domain;
}
trace_xfs_refcount_find_left_extent(cur->bc_mp, cur->bc_ag.pag->pag_agno,
left, cleft, agbno);
return error;
out_error:
trace_xfs_refcount_find_left_extent_error(cur->bc_mp,
cur->bc_ag.pag->pag_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,
enum xfs_refc_domain domain,
xfs_agblock_t agbno,
xfs_extlen_t aglen)
{
struct xfs_refcount_irec tmp;
int error;
int found_rec;
right->rc_startblock = cright->rc_startblock = NULLAGBLOCK;
error = xfs_refcount_lookup_ge(cur, domain, 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;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (tmp.rc_domain != domain)
return 0;
if (tmp.rc_startblock != agbno + aglen)
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;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (tmp.rc_domain != domain)
goto not_found;
/* 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;
cright->rc_domain = domain;
}
} else {
not_found:
/*
* No extents, so pretend that there's one covering the whole
* range.
*/
cright->rc_startblock = agbno;
cright->rc_blockcount = aglen;
cright->rc_refcount = 1;
cright->rc_domain = domain;
}
trace_xfs_refcount_find_right_extent(cur->bc_mp, cur->bc_ag.pag->pag_agno,
cright, right, agbno + aglen);
return error;
out_error:
trace_xfs_refcount_find_right_extent_error(cur->bc_mp,
cur->bc_ag.pag->pag_agno, error, _RET_IP_);
return error;
}
/* Is this extent valid? */
static inline bool
xfs_refc_valid(
const struct xfs_refcount_irec *rc)
{
return rc->rc_startblock != NULLAGBLOCK;
}
static inline xfs_nlink_t
xfs_refc_merge_refcount(
const struct xfs_refcount_irec *irec,
enum xfs_refc_adjust_op adjust)
{
/* Once a record hits MAXREFCOUNT, it is pinned there forever */
if (irec->rc_refcount == MAXREFCOUNT)
return MAXREFCOUNT;
return irec->rc_refcount + adjust;
}
static inline bool
xfs_refc_want_merge_center(
const struct xfs_refcount_irec *left,
const struct xfs_refcount_irec *cleft,
const struct xfs_refcount_irec *cright,
const struct xfs_refcount_irec *right,
bool cleft_is_cright,
enum xfs_refc_adjust_op adjust,
unsigned long long *ulenp)
{
unsigned long long ulen = left->rc_blockcount;
xfs_nlink_t new_refcount;
/*
* To merge with a center record, both shoulder records must be
* adjacent to the record we want to adjust. This is only true if
* find_left and find_right made all four records valid.
*/
if (!xfs_refc_valid(left) || !xfs_refc_valid(right) ||
!xfs_refc_valid(cleft) || !xfs_refc_valid(cright))
return false;
/* There must only be one record for the entire range. */
if (!cleft_is_cright)
return false;
/* The shoulder record refcounts must match the new refcount. */
new_refcount = xfs_refc_merge_refcount(cleft, adjust);
if (left->rc_refcount != new_refcount)
return false;
if (right->rc_refcount != new_refcount)
return false;
/*
* The new record cannot exceed the max length. ulen is a ULL as the
* individual record block counts can be up to (u32 - 1) in length
* hence we need to catch u32 addition overflows here.
*/
ulen += cleft->rc_blockcount + right->rc_blockcount;
if (ulen >= MAXREFCEXTLEN)
return false;
*ulenp = ulen;
return true;
}
static inline bool
xfs_refc_want_merge_left(
const struct xfs_refcount_irec *left,
const struct xfs_refcount_irec *cleft,
enum xfs_refc_adjust_op adjust)
{
unsigned long long ulen = left->rc_blockcount;
xfs_nlink_t new_refcount;
/*
* For a left merge, the left shoulder record must be adjacent to the
* start of the range. If this is true, find_left made left and cleft
* contain valid contents.
*/
if (!xfs_refc_valid(left) || !xfs_refc_valid(cleft))
return false;
/* Left shoulder record refcount must match the new refcount. */
new_refcount = xfs_refc_merge_refcount(cleft, adjust);
if (left->rc_refcount != new_refcount)
return false;
/*
* The new record cannot exceed the max length. ulen is a ULL as the
* individual record block counts can be up to (u32 - 1) in length
* hence we need to catch u32 addition overflows here.
*/
ulen += cleft->rc_blockcount;
if (ulen >= MAXREFCEXTLEN)
return false;
return true;
}
static inline bool
xfs_refc_want_merge_right(
const struct xfs_refcount_irec *cright,
const struct xfs_refcount_irec *right,
enum xfs_refc_adjust_op adjust)
{
unsigned long long ulen = right->rc_blockcount;
xfs_nlink_t new_refcount;
/*
* For a right merge, the right shoulder record must be adjacent to the
* end of the range. If this is true, find_right made cright and right
* contain valid contents.
*/
if (!xfs_refc_valid(right) || !xfs_refc_valid(cright))
return false;
/* Right shoulder record refcount must match the new refcount. */
new_refcount = xfs_refc_merge_refcount(cright, adjust);
if (right->rc_refcount != new_refcount)
return false;
/*
* The new record cannot exceed the max length. ulen is a ULL as the
* individual record block counts can be up to (u32 - 1) in length
* hence we need to catch u32 addition overflows here.
*/
ulen += cright->rc_blockcount;
if (ulen >= MAXREFCEXTLEN)
return false;
return true;
}
/*
* Try to merge with any extents on the boundaries of the adjustment range.
*/
STATIC int
xfs_refcount_merge_extents(
struct xfs_btree_cur *cur,
enum xfs_refc_domain domain,
xfs_agblock_t *agbno,
xfs_extlen_t *aglen,
enum xfs_refc_adjust_op adjust,
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, domain,
*agbno, *aglen);
if (error)
return error;
error = xfs_refcount_find_right_extents(cur, &right, &cright, domain,
*agbno, *aglen);
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. */
if (xfs_refc_want_merge_center(&left, &cleft, &cright, &right, cequal,
adjust, &ulen)) {
*shape_changed = true;
return xfs_refcount_merge_center_extents(cur, &left, &cleft,
&right, ulen, aglen);
}
/* Try to merge left and cleft. */
if (xfs_refc_want_merge_left(&left, &cleft, adjust)) {
*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. */
if (xfs_refc_want_merge_right(&cright, &right, adjust)) {
*shape_changed = true;
return xfs_refcount_merge_right_extent(cur, &right, &cright,
aglen);
}
return 0;
}
/*
* 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;
/*
* Worst case estimate: full splits of the free space and rmap btrees
* to handle each of the shape changes to the refcount btree.
*/
overhead = xfs_allocfree_block_count(cur->bc_mp,
cur->bc_ag.refc.shape_changes);
overhead += cur->bc_mp->m_refc_maxlevels;
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_ag.refc.nr_ops > 2 &&
XFS_TEST_ERROR(false, cur->bc_mp,
XFS_ERRTAG_REFCOUNT_CONTINUE_UPDATE))
return false;
if (cur->bc_ag.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_ag.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_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, XFS_REFC_DOMAIN_SHARED, *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_domain != XFS_REFC_DOMAIN_SHARED) {
ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
ext.rc_blockcount = 0;
ext.rc_refcount = 0;
ext.rc_domain = XFS_REFC_DOMAIN_SHARED;
}
/*
* 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;
tmp.rc_domain = XFS_REFC_DOMAIN_SHARED;
trace_xfs_refcount_modify_extent(cur->bc_mp,
cur->bc_ag.pag->pag_agno, &tmp);
/*
* Either cover the hole (increment) or
* delete the range (decrement).
*/
cur->bc_ag.refc.nr_ops++;
if (tmp.rc_refcount) {
error = xfs_refcount_insert(cur, &tmp,
&found_tmp);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp,
found_tmp != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
} else {
fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
cur->bc_ag.pag->pag_agno,
tmp.rc_startblock);
xfs_free_extent_later(cur->bc_tp, fsbno,
tmp.rc_blockcount, NULL);
}
(*agbno) += tmp.rc_blockcount;
(*aglen) -= tmp.rc_blockcount;
/* Stop if there's nothing left to modify */
if (*aglen == 0 || !xfs_refcount_still_have_space(cur))
break;
/* Move the cursor to the start of ext. */
error = xfs_refcount_lookup_ge(cur,
XFS_REFC_DOMAIN_SHARED, *agbno,
&found_rec);
if (error)
goto out_error;
}
/*
* A previous step trimmed agbno/aglen such that the end of the
* range would not be in the middle of the record. If this is
* no longer the case, something is seriously wrong with the
* btree. Make sure we never feed the synthesized record into
* the processing loop below.
*/
if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_blockcount == 0) ||
XFS_IS_CORRUPT(cur->bc_mp, ext.rc_blockcount > *aglen)) {
error = -EFSCORRUPTED;
goto out_error;
}
/*
* 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_ag.pag->pag_agno, &ext);
cur->bc_ag.refc.nr_ops++;
if (ext.rc_refcount > 1) {
error = xfs_refcount_update(cur, &ext);
if (error)
goto out_error;
} else if (ext.rc_refcount == 1) {
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
goto advloop;
} else {
fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
cur->bc_ag.pag->pag_agno,
ext.rc_startblock);
xfs_free_extent_later(cur->bc_tp, fsbno,
ext.rc_blockcount, NULL);
}
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_ag.pag->pag_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,
enum xfs_refc_adjust_op adj)
{
bool shape_changed;
int shape_changes = 0;
int error;
if (adj == XFS_REFCOUNT_ADJUST_INCREASE)
trace_xfs_refcount_increase(cur->bc_mp,
cur->bc_ag.pag->pag_agno, *agbno, *aglen);
else
trace_xfs_refcount_decrease(cur->bc_mp,
cur->bc_ag.pag->pag_agno, *agbno, *aglen);
/*
* Ensure that no rcextents cross the boundary of the adjustment range.
*/
error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_SHARED,
*agbno, &shape_changed);
if (error)
goto out_error;
if (shape_changed)
shape_changes++;
error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_SHARED,
*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, XFS_REFC_DOMAIN_SHARED,
agbno, aglen, adj, &shape_changed);
if (error)
goto out_error;
if (shape_changed)
shape_changes++;
if (shape_changes)
cur->bc_ag.refc.shape_changes++;
/* Now that we've taken care of the ends, adjust the middle extents */
error = xfs_refcount_adjust_extents(cur, agbno, aglen, adj);
if (error)
goto out_error;
return 0;
out_error:
trace_xfs_refcount_adjust_error(cur->bc_mp, cur->bc_ag.pag->pag_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_ag.agbp;
xfs_btree_del_cursor(rcur, error);
if (error)
xfs_trans_brelse(tp, agbp);
}
/*
* Set up a continuation a deferred refcount operation by updating the intent.
* Checks to make sure we're not going to run off the end of the AG.
*/
static inline int
xfs_refcount_continue_op(
struct xfs_btree_cur *cur,
struct xfs_refcount_intent *ri,
xfs_agblock_t new_agbno)
{
struct xfs_mount *mp = cur->bc_mp;
struct xfs_perag *pag = cur->bc_ag.pag;
if (XFS_IS_CORRUPT(mp, !xfs_verify_agbext(pag, new_agbno,
ri->ri_blockcount)))
return -EFSCORRUPTED;
ri->ri_startblock = XFS_AGB_TO_FSB(mp, pag->pag_agno, new_agbno);
ASSERT(xfs_verify_fsbext(mp, ri->ri_startblock, ri->ri_blockcount));
ASSERT(pag->pag_agno == XFS_FSB_TO_AGNO(mp, ri->ri_startblock));
return 0;
}
/*
* 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_refcount_intent *ri,
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_agblock_t bno;
unsigned long nr_ops = 0;
int shape_changes = 0;
struct xfs_perag *pag;
pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, ri->ri_startblock));
bno = XFS_FSB_TO_AGBNO(mp, ri->ri_startblock);
trace_xfs_refcount_deferred(mp, XFS_FSB_TO_AGNO(mp, ri->ri_startblock),
ri->ri_type, XFS_FSB_TO_AGBNO(mp, ri->ri_startblock),
ri->ri_blockcount);
if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_REFCOUNT_FINISH_ONE)) {
error = -EIO;
goto out_drop;
}
/*
* 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_ag.pag != pag) {
nr_ops = rcur->bc_ag.refc.nr_ops;
shape_changes = rcur->bc_ag.refc.shape_changes;
xfs_refcount_finish_one_cleanup(tp, rcur, 0);
rcur = NULL;
*pcur = NULL;
}
if (rcur == NULL) {
error = xfs_alloc_read_agf(pag, tp, XFS_ALLOC_FLAG_FREEING,
&agbp);
if (error)
goto out_drop;
rcur = xfs_refcountbt_init_cursor(mp, tp, agbp, pag);
rcur->bc_ag.refc.nr_ops = nr_ops;
rcur->bc_ag.refc.shape_changes = shape_changes;
}
*pcur = rcur;
switch (ri->ri_type) {
case XFS_REFCOUNT_INCREASE:
error = xfs_refcount_adjust(rcur, &bno, &ri->ri_blockcount,
XFS_REFCOUNT_ADJUST_INCREASE);
if (error)
goto out_drop;
if (ri->ri_blockcount > 0)
error = xfs_refcount_continue_op(rcur, ri, bno);
break;
case XFS_REFCOUNT_DECREASE:
error = xfs_refcount_adjust(rcur, &bno, &ri->ri_blockcount,
XFS_REFCOUNT_ADJUST_DECREASE);
if (error)
goto out_drop;
if (ri->ri_blockcount > 0)
error = xfs_refcount_continue_op(rcur, ri, bno);
break;
case XFS_REFCOUNT_ALLOC_COW:
error = __xfs_refcount_cow_alloc(rcur, bno, ri->ri_blockcount);
if (error)
goto out_drop;
ri->ri_blockcount = 0;
break;
case XFS_REFCOUNT_FREE_COW:
error = __xfs_refcount_cow_free(rcur, bno, ri->ri_blockcount);
if (error)
goto out_drop;
ri->ri_blockcount = 0;
break;
default:
ASSERT(0);
error = -EFSCORRUPTED;
}
if (!error && ri->ri_blockcount > 0)
trace_xfs_refcount_finish_one_leftover(mp, pag->pag_agno,
ri->ri_type, bno, ri->ri_blockcount);
out_drop:
xfs_perag_put(pag);
return error;
}
/*
* Record a refcount intent for later processing.
*/
static void
__xfs_refcount_add(
struct xfs_trans *tp,
enum xfs_refcount_intent_type type,
xfs_fsblock_t startblock,
xfs_extlen_t blockcount)
{
struct xfs_refcount_intent *ri;
trace_xfs_refcount_defer(tp->t_mountp,
XFS_FSB_TO_AGNO(tp->t_mountp, startblock),
type, XFS_FSB_TO_AGBNO(tp->t_mountp, startblock),
blockcount);
ri = kmem_cache_alloc(xfs_refcount_intent_cache,
GFP_NOFS | __GFP_NOFAIL);
INIT_LIST_HEAD(&ri->ri_list);
ri->ri_type = type;
ri->ri_startblock = startblock;
ri->ri_blockcount = blockcount;
xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_REFCOUNT, &ri->ri_list);
}
/*
* Increase the reference count of the blocks backing a file's extent.
*/
void
xfs_refcount_increase_extent(
struct xfs_trans *tp,
struct xfs_bmbt_irec *PREV)
{
if (!xfs_has_reflink(tp->t_mountp))
return;
__xfs_refcount_add(tp, XFS_REFCOUNT_INCREASE, PREV->br_startblock,
PREV->br_blockcount);
}
/*
* Decrease the reference count of the blocks backing a file's extent.
*/
void
xfs_refcount_decrease_extent(
struct xfs_trans *tp,
struct xfs_bmbt_irec *PREV)
{
if (!xfs_has_reflink(tp->t_mountp))
return;
__xfs_refcount_add(tp, 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_ag.pag->pag_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, XFS_REFC_DOMAIN_SHARED, 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;
if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED)
goto done;
/* 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;
if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED)
goto done;
}
/* 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;
if (XFS_IS_CORRUPT(cur->bc_mp, i != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (tmp.rc_domain != XFS_REFC_DOMAIN_SHARED ||
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_ag.pag->pag_agno, *fbno, *flen);
out_error:
if (error)
trace_xfs_refcount_find_shared_error(cur->bc_mp,
cur->bc_ag.pag->pag_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_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, XFS_REFC_DOMAIN_COW, agbno,
&found_rec);
if (error)
goto out_error;
error = xfs_refcount_get_rec(cur, &ext, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec &&
ext.rc_domain != XFS_REFC_DOMAIN_COW)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (!found_rec) {
ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
ext.rc_blockcount = 0;
ext.rc_refcount = 0;
ext.rc_domain = XFS_REFC_DOMAIN_COW;
}
switch (adj) {
case XFS_REFCOUNT_ADJUST_COW_ALLOC:
/* Adding a CoW reservation, there should be nothing here. */
if (XFS_IS_CORRUPT(cur->bc_mp,
agbno + aglen > ext.rc_startblock)) {
error = -EFSCORRUPTED;
goto out_error;
}
tmp.rc_startblock = agbno;
tmp.rc_blockcount = aglen;
tmp.rc_refcount = 1;
tmp.rc_domain = XFS_REFC_DOMAIN_COW;
trace_xfs_refcount_modify_extent(cur->bc_mp,
cur->bc_ag.pag->pag_agno, &tmp);
error = xfs_refcount_insert(cur, &tmp,
&found_tmp);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_tmp != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
break;
case XFS_REFCOUNT_ADJUST_COW_FREE:
/* Removing a CoW reservation, there should be one extent. */
if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_startblock != agbno)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_blockcount != aglen)) {
error = -EFSCORRUPTED;
goto out_error;
}
if (XFS_IS_CORRUPT(cur->bc_mp, ext.rc_refcount != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
ext.rc_refcount = 0;
trace_xfs_refcount_modify_extent(cur->bc_mp,
cur->bc_ag.pag->pag_agno, &ext);
error = xfs_refcount_delete(cur, &found_rec);
if (error)
goto out_error;
if (XFS_IS_CORRUPT(cur->bc_mp, found_rec != 1)) {
error = -EFSCORRUPTED;
goto out_error;
}
break;
default:
ASSERT(0);
}
return error;
out_error:
trace_xfs_refcount_modify_extent_error(cur->bc_mp,
cur->bc_ag.pag->pag_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)
{
bool shape_changed;
int error;
/*
* Ensure that no rcextents cross the boundary of the adjustment range.
*/
error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_COW,
agbno, &shape_changed);
if (error)
goto out_error;
error = xfs_refcount_split_extent(cur, XFS_REFC_DOMAIN_COW,
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, XFS_REFC_DOMAIN_COW, &agbno,
&aglen, adj, &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);
if (error)
goto out_error;
return 0;
out_error:
trace_xfs_refcount_adjust_cow_error(cur->bc_mp, cur->bc_ag.pag->pag_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)
{
trace_xfs_refcount_cow_increase(rcur->bc_mp, rcur->bc_ag.pag->pag_agno,
agbno, aglen);
/* Add refcount btree reservation */
return xfs_refcount_adjust_cow(rcur, agbno, aglen,
XFS_REFCOUNT_ADJUST_COW_ALLOC);
}
/*
* 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)
{
trace_xfs_refcount_cow_decrease(rcur->bc_mp, rcur->bc_ag.pag->pag_agno,
agbno, aglen);
/* Remove refcount btree reservation */
return xfs_refcount_adjust_cow(rcur, agbno, aglen,
XFS_REFCOUNT_ADJUST_COW_FREE);
}
/* Record a CoW staging extent in the refcount btree. */
void
xfs_refcount_alloc_cow_extent(
struct xfs_trans *tp,
xfs_fsblock_t fsb,
xfs_extlen_t len)
{
struct xfs_mount *mp = tp->t_mountp;
if (!xfs_has_reflink(mp))
return;
__xfs_refcount_add(tp, XFS_REFCOUNT_ALLOC_COW, fsb, len);
/* Add rmap entry */
xfs_rmap_alloc_extent(tp, XFS_FSB_TO_AGNO(mp, fsb),
XFS_FSB_TO_AGBNO(mp, fsb), len, XFS_RMAP_OWN_COW);
}
/* Forget a CoW staging event in the refcount btree. */
void
xfs_refcount_free_cow_extent(
struct xfs_trans *tp,
xfs_fsblock_t fsb,
xfs_extlen_t len)
{
struct xfs_mount *mp = tp->t_mountp;
if (!xfs_has_reflink(mp))
return;
/* Remove rmap entry */
xfs_rmap_free_extent(tp, XFS_FSB_TO_AGNO(mp, fsb),
XFS_FSB_TO_AGBNO(mp, fsb), len, XFS_RMAP_OWN_COW);
__xfs_refcount_add(tp, 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,
const union xfs_btree_rec *rec,
void *priv)
{
struct list_head *debris = priv;
struct xfs_refcount_recovery *rr;
if (XFS_IS_CORRUPT(cur->bc_mp,
be32_to_cpu(rec->refc.rc_refcount) != 1))
return -EFSCORRUPTED;
rr = kmalloc(sizeof(struct xfs_refcount_recovery),
GFP_KERNEL | __GFP_NOFAIL);
INIT_LIST_HEAD(&rr->rr_list);
xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
if (XFS_IS_CORRUPT(cur->bc_mp,
rr->rr_rrec.rc_domain != XFS_REFC_DOMAIN_COW)) {
kfree(rr);
return -EFSCORRUPTED;
}
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,
struct xfs_perag *pag)
{
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;
xfs_fsblock_t fsb;
int error;
/* reflink filesystems mustn't have AGs larger than 2^31-1 blocks */
BUILD_BUG_ON(XFS_MAX_CRC_AG_BLOCKS >= XFS_REFC_COWFLAG);
if (mp->m_sb.sb_agblocks > XFS_MAX_CRC_AG_BLOCKS)
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(pag, tp, 0, &agbp);
if (error)
goto out_trans;
cur = xfs_refcountbt_init_cursor(mp, tp, agbp, pag);
/* Find all the leftover CoW staging extents. */
memset(&low, 0, sizeof(low));
memset(&high, 0, sizeof(high));
low.rc.rc_domain = high.rc.rc_domain = XFS_REFC_DOMAIN_COW;
high.rc.rc_startblock = -1U;
error = xfs_btree_query_range(cur, &low, &high,
xfs_refcount_recover_extent, &debris);
xfs_btree_del_cursor(cur, error);
xfs_trans_brelse(tp, agbp);
xfs_trans_cancel(tp);
if (error)
goto out_free;
/* 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, pag->pag_agno,
&rr->rr_rrec);
/* Free the orphan record */
fsb = XFS_AGB_TO_FSB(mp, pag->pag_agno,
rr->rr_rrec.rc_startblock);
xfs_refcount_free_cow_extent(tp, fsb,
rr->rr_rrec.rc_blockcount);
/* Free the block. */
xfs_free_extent_later(tp, fsb, rr->rr_rrec.rc_blockcount, NULL);
error = xfs_trans_commit(tp);
if (error)
goto out_free;
list_del(&rr->rr_list);
kfree(rr);
}
return error;
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);
kfree(rr);
}
return error;
}
/* Is there a record covering a given extent? */
int
xfs_refcount_has_record(
struct xfs_btree_cur *cur,
enum xfs_refc_domain domain,
xfs_agblock_t bno,
xfs_extlen_t len,
bool *exists)
{
union xfs_btree_irec low;
union xfs_btree_irec high;
memset(&low, 0, sizeof(low));
low.rc.rc_startblock = bno;
memset(&high, 0xFF, sizeof(high));
high.rc.rc_startblock = bno + len - 1;
low.rc.rc_domain = high.rc.rc_domain = domain;
return xfs_btree_has_record(cur, &low, &high, exists);
}
int __init
xfs_refcount_intent_init_cache(void)
{
xfs_refcount_intent_cache = kmem_cache_create("xfs_refc_intent",
sizeof(struct xfs_refcount_intent),
0, 0, NULL);
return xfs_refcount_intent_cache != NULL ? 0 : -ENOMEM;
}
void
xfs_refcount_intent_destroy_cache(void)
{
kmem_cache_destroy(xfs_refcount_intent_cache);
xfs_refcount_intent_cache = NULL;
}