diff options
Diffstat (limited to '')
| -rw-r--r-- | fs/xfs/libxfs/xfs_refcount.c | 2051 |
1 files changed, 2051 insertions, 0 deletions
diff --git a/fs/xfs/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c new file mode 100644 index 0000000000..646b3fa362 --- /dev/null +++ b/fs/xfs/libxfs/xfs_refcount.c @@ -0,0 +1,2051 @@ +// 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); +} + +/* Simple checks for refcount records. */ +xfs_failaddr_t +xfs_refcount_check_irec( + struct xfs_btree_cur *cur, + const struct xfs_refcount_irec *irec) +{ + struct xfs_perag *pag = cur->bc_ag.pag; + + if (irec->rc_blockcount == 0 || irec->rc_blockcount > MAXREFCEXTLEN) + return __this_address; + + if (!xfs_refcount_check_domain(irec)) + return __this_address; + + /* check for valid extent range, including overflow */ + if (!xfs_verify_agbext(pag, irec->rc_startblock, irec->rc_blockcount)) + return __this_address; + + if (irec->rc_refcount == 0 || irec->rc_refcount > MAXREFCOUNT) + return __this_address; + + return NULL; +} + +static inline int +xfs_refcount_complain_bad_rec( + struct xfs_btree_cur *cur, + xfs_failaddr_t fa, + const struct xfs_refcount_irec *irec) +{ + struct xfs_mount *mp = cur->bc_mp; + + xfs_warn(mp, + "Refcount BTree record corruption in AG %d detected at %pS!", + cur->bc_ag.pag->pag_agno, fa); + 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; +} + +/* + * 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; + xfs_failaddr_t fa; + int error; + + error = xfs_btree_get_rec(cur, &rec, stat); + if (error || !*stat) + return error; + + xfs_refcount_btrec_to_irec(rec, irec); + fa = xfs_refcount_check_irec(cur, irec); + if (fa) + return xfs_refcount_complain_bad_rec(cur, fa, irec); + + trace_xfs_refcount_get(cur->bc_mp, cur->bc_ag.pag->pag_agno, irec); + return 0; +} + +/* + * 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); + error = xfs_free_extent_later(cur->bc_tp, fsbno, + tmp.rc_blockcount, NULL, + XFS_AG_RESV_NONE); + if (error) + goto out_error; + } + + (*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); + error = xfs_free_extent_later(cur->bc_tp, fsbno, + ext.rc_blockcount, NULL, + XFS_AG_RESV_NONE); + if (error) + goto out_error; + } + +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; + + 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)) + 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_ag.pag != ri->ri_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(ri->ri_pag, tp, + XFS_ALLOC_FLAG_FREEING, &agbp); + if (error) + return error; + + rcur = xfs_refcountbt_init_cursor(mp, tp, agbp, ri->ri_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) + return error; + 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) + return error; + 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) + return error; + ri->ri_blockcount = 0; + break; + case XFS_REFCOUNT_FREE_COW: + error = __xfs_refcount_cow_free(rcur, bno, ri->ri_blockcount); + if (error) + return error; + ri->ri_blockcount = 0; + break; + default: + ASSERT(0); + return -EFSCORRUPTED; + } + if (!error && ri->ri_blockcount > 0) + trace_xfs_refcount_finish_one_leftover(mp, ri->ri_pag->pag_agno, + ri->ri_type, bno, ri->ri_blockcount); + 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_refcount_update_get_group(tp->t_mountp, ri); + 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_refcount_check_irec(cur, &rr->rr_rrec) != NULL || + 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 = { + .rc.rc_domain = XFS_REFC_DOMAIN_COW, + }; + union xfs_btree_irec high = { + .rc.rc_domain = XFS_REFC_DOMAIN_COW, + .rc.rc_startblock = -1U, + }; + 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. */ + 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. */ + error = xfs_free_extent_later(tp, fsb, + rr->rr_rrec.rc_blockcount, NULL, + XFS_AG_RESV_NONE); + if (error) + goto out_trans; + + 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; +} + +/* + * Scan part of the keyspace of the refcount records and tell us if the area + * has no records, is fully mapped by records, or is partially filled. + */ +int +xfs_refcount_has_records( + struct xfs_btree_cur *cur, + enum xfs_refc_domain domain, + xfs_agblock_t bno, + xfs_extlen_t len, + enum xbtree_recpacking *outcome) +{ + 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_records(cur, &low, &high, NULL, outcome); +} + +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; +} |