diff options
Diffstat (limited to 'fs/xfs/scrub/reap.c')
-rw-r--r-- | fs/xfs/scrub/reap.c | 498 |
1 files changed, 498 insertions, 0 deletions
diff --git a/fs/xfs/scrub/reap.c b/fs/xfs/scrub/reap.c new file mode 100644 index 000000000000..86a62420e02c --- /dev/null +++ b/fs/xfs/scrub/reap.c @@ -0,0 +1,498 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2022-2023 Oracle. All Rights Reserved. + * Author: Darrick J. Wong <djwong@kernel.org> + */ +#include "xfs.h" +#include "xfs_fs.h" +#include "xfs_shared.h" +#include "xfs_format.h" +#include "xfs_trans_resv.h" +#include "xfs_mount.h" +#include "xfs_btree.h" +#include "xfs_log_format.h" +#include "xfs_trans.h" +#include "xfs_sb.h" +#include "xfs_inode.h" +#include "xfs_alloc.h" +#include "xfs_alloc_btree.h" +#include "xfs_ialloc.h" +#include "xfs_ialloc_btree.h" +#include "xfs_rmap.h" +#include "xfs_rmap_btree.h" +#include "xfs_refcount_btree.h" +#include "xfs_extent_busy.h" +#include "xfs_ag.h" +#include "xfs_ag_resv.h" +#include "xfs_quota.h" +#include "xfs_qm.h" +#include "xfs_bmap.h" +#include "xfs_da_format.h" +#include "xfs_da_btree.h" +#include "xfs_attr.h" +#include "xfs_attr_remote.h" +#include "scrub/scrub.h" +#include "scrub/common.h" +#include "scrub/trace.h" +#include "scrub/repair.h" +#include "scrub/bitmap.h" +#include "scrub/reap.h" + +/* + * Disposal of Blocks from Old Metadata + * + * Now that we've constructed a new btree to replace the damaged one, we want + * to dispose of the blocks that (we think) the old btree was using. + * Previously, we used the rmapbt to collect the extents (bitmap) with the + * rmap owner corresponding to the tree we rebuilt, collected extents for any + * blocks with the same rmap owner that are owned by another data structure + * (sublist), and subtracted sublist from bitmap. In theory the extents + * remaining in bitmap are the old btree's blocks. + * + * Unfortunately, it's possible that the btree was crosslinked with other + * blocks on disk. The rmap data can tell us if there are multiple owners, so + * if the rmapbt says there is an owner of this block other than @oinfo, then + * the block is crosslinked. Remove the reverse mapping and continue. + * + * If there is one rmap record, we can free the block, which removes the + * reverse mapping but doesn't add the block to the free space. Our repair + * strategy is to hope the other metadata objects crosslinked on this block + * will be rebuilt (atop different blocks), thereby removing all the cross + * links. + * + * If there are no rmap records at all, we also free the block. If the btree + * being rebuilt lives in the free space (bnobt/cntbt/rmapbt) then there isn't + * supposed to be a rmap record and everything is ok. For other btrees there + * had to have been an rmap entry for the block to have ended up on @bitmap, + * so if it's gone now there's something wrong and the fs will shut down. + * + * Note: If there are multiple rmap records with only the same rmap owner as + * the btree we're trying to rebuild and the block is indeed owned by another + * data structure with the same rmap owner, then the block will be in sublist + * and therefore doesn't need disposal. If there are multiple rmap records + * with only the same rmap owner but the block is not owned by something with + * the same rmap owner, the block will be freed. + * + * The caller is responsible for locking the AG headers for the entire rebuild + * operation so that nothing else can sneak in and change the AG state while + * we're not looking. We must also invalidate any buffers associated with + * @bitmap. + */ + +/* Information about reaping extents after a repair. */ +struct xreap_state { + struct xfs_scrub *sc; + + /* Reverse mapping owner and metadata reservation type. */ + const struct xfs_owner_info *oinfo; + enum xfs_ag_resv_type resv; + + /* If true, roll the transaction before reaping the next extent. */ + bool force_roll; + + /* Number of deferred reaps attached to the current transaction. */ + unsigned int deferred; + + /* Number of invalidated buffers logged to the current transaction. */ + unsigned int invalidated; + + /* Number of deferred reaps queued during the whole reap sequence. */ + unsigned long long total_deferred; +}; + +/* Put a block back on the AGFL. */ +STATIC int +xreap_put_freelist( + struct xfs_scrub *sc, + xfs_agblock_t agbno) +{ + struct xfs_buf *agfl_bp; + int error; + + /* Make sure there's space on the freelist. */ + error = xrep_fix_freelist(sc, true); + if (error) + return error; + + /* + * Since we're "freeing" a lost block onto the AGFL, we have to + * create an rmap for the block prior to merging it or else other + * parts will break. + */ + error = xfs_rmap_alloc(sc->tp, sc->sa.agf_bp, sc->sa.pag, agbno, 1, + &XFS_RMAP_OINFO_AG); + if (error) + return error; + + /* Put the block on the AGFL. */ + error = xfs_alloc_read_agfl(sc->sa.pag, sc->tp, &agfl_bp); + if (error) + return error; + + error = xfs_alloc_put_freelist(sc->sa.pag, sc->tp, sc->sa.agf_bp, + agfl_bp, agbno, 0); + if (error) + return error; + xfs_extent_busy_insert(sc->tp, sc->sa.pag, agbno, 1, + XFS_EXTENT_BUSY_SKIP_DISCARD); + + return 0; +} + +/* Are there any uncommitted reap operations? */ +static inline bool xreap_dirty(const struct xreap_state *rs) +{ + if (rs->force_roll) + return true; + if (rs->deferred) + return true; + if (rs->invalidated) + return true; + if (rs->total_deferred) + return true; + return false; +} + +#define XREAP_MAX_BINVAL (2048) + +/* + * Decide if we want to roll the transaction after reaping an extent. We don't + * want to overrun the transaction reservation, so we prohibit more than + * 128 EFIs per transaction. For the same reason, we limit the number + * of buffer invalidations to 2048. + */ +static inline bool xreap_want_roll(const struct xreap_state *rs) +{ + if (rs->force_roll) + return true; + if (rs->deferred > XREP_MAX_ITRUNCATE_EFIS) + return true; + if (rs->invalidated > XREAP_MAX_BINVAL) + return true; + return false; +} + +static inline void xreap_reset(struct xreap_state *rs) +{ + rs->total_deferred += rs->deferred; + rs->deferred = 0; + rs->invalidated = 0; + rs->force_roll = false; +} + +#define XREAP_MAX_DEFER_CHAIN (2048) + +/* + * Decide if we want to finish the deferred ops that are attached to the scrub + * transaction. We don't want to queue huge chains of deferred ops because + * that can consume a lot of log space and kernel memory. Hence we trigger a + * xfs_defer_finish if there are more than 2048 deferred reap operations or the + * caller did some real work. + */ +static inline bool +xreap_want_defer_finish(const struct xreap_state *rs) +{ + if (rs->force_roll) + return true; + if (rs->total_deferred > XREAP_MAX_DEFER_CHAIN) + return true; + return false; +} + +static inline void xreap_defer_finish_reset(struct xreap_state *rs) +{ + rs->total_deferred = 0; + rs->deferred = 0; + rs->invalidated = 0; + rs->force_roll = false; +} + +/* Try to invalidate the incore buffers for an extent that we're freeing. */ +STATIC void +xreap_agextent_binval( + struct xreap_state *rs, + xfs_agblock_t agbno, + xfs_extlen_t *aglenp) +{ + struct xfs_scrub *sc = rs->sc; + struct xfs_perag *pag = sc->sa.pag; + struct xfs_mount *mp = sc->mp; + xfs_agnumber_t agno = sc->sa.pag->pag_agno; + xfs_agblock_t agbno_next = agbno + *aglenp; + xfs_agblock_t bno = agbno; + + /* + * Avoid invalidating AG headers and post-EOFS blocks because we never + * own those. + */ + if (!xfs_verify_agbno(pag, agbno) || + !xfs_verify_agbno(pag, agbno_next - 1)) + return; + + /* + * If there are incore buffers for these blocks, invalidate them. We + * assume that the lack of any other known owners means that the buffer + * can be locked without risk of deadlocking. The buffer cache cannot + * detect aliasing, so employ nested loops to scan for incore buffers + * of any plausible size. + */ + while (bno < agbno_next) { + xfs_agblock_t fsbcount; + xfs_agblock_t max_fsbs; + + /* + * Max buffer size is the max remote xattr buffer size, which + * is one fs block larger than 64k. + */ + max_fsbs = min_t(xfs_agblock_t, agbno_next - bno, + xfs_attr3_rmt_blocks(mp, XFS_XATTR_SIZE_MAX)); + + for (fsbcount = 1; fsbcount < max_fsbs; fsbcount++) { + struct xfs_buf *bp = NULL; + xfs_daddr_t daddr; + int error; + + daddr = XFS_AGB_TO_DADDR(mp, agno, bno); + error = xfs_buf_incore(mp->m_ddev_targp, daddr, + XFS_FSB_TO_BB(mp, fsbcount), + XBF_LIVESCAN, &bp); + if (error) + continue; + + xfs_trans_bjoin(sc->tp, bp); + xfs_trans_binval(sc->tp, bp); + rs->invalidated++; + + /* + * Stop invalidating if we've hit the limit; we should + * still have enough reservation left to free however + * far we've gotten. + */ + if (rs->invalidated > XREAP_MAX_BINVAL) { + *aglenp -= agbno_next - bno; + goto out; + } + } + + bno++; + } + +out: + trace_xreap_agextent_binval(sc->sa.pag, agbno, *aglenp); +} + +/* + * Figure out the longest run of blocks that we can dispose of with a single + * call. Cross-linked blocks should have their reverse mappings removed, but + * single-owner extents can be freed. AGFL blocks can only be put back one at + * a time. + */ +STATIC int +xreap_agextent_select( + struct xreap_state *rs, + xfs_agblock_t agbno, + xfs_agblock_t agbno_next, + bool *crosslinked, + xfs_extlen_t *aglenp) +{ + struct xfs_scrub *sc = rs->sc; + struct xfs_btree_cur *cur; + xfs_agblock_t bno = agbno + 1; + xfs_extlen_t len = 1; + int error; + + /* + * Determine if there are any other rmap records covering the first + * block of this extent. If so, the block is crosslinked. + */ + cur = xfs_rmapbt_init_cursor(sc->mp, sc->tp, sc->sa.agf_bp, + sc->sa.pag); + error = xfs_rmap_has_other_keys(cur, agbno, 1, rs->oinfo, + crosslinked); + if (error) + goto out_cur; + + /* AGFL blocks can only be deal with one at a time. */ + if (rs->resv == XFS_AG_RESV_AGFL) + goto out_found; + + /* + * Figure out how many of the subsequent blocks have the same crosslink + * status. + */ + while (bno < agbno_next) { + bool also_crosslinked; + + error = xfs_rmap_has_other_keys(cur, bno, 1, rs->oinfo, + &also_crosslinked); + if (error) + goto out_cur; + + if (*crosslinked != also_crosslinked) + break; + + len++; + bno++; + } + +out_found: + *aglenp = len; + trace_xreap_agextent_select(sc->sa.pag, agbno, len, *crosslinked); +out_cur: + xfs_btree_del_cursor(cur, error); + return error; +} + +/* + * Dispose of as much of the beginning of this AG extent as possible. The + * number of blocks disposed of will be returned in @aglenp. + */ +STATIC int +xreap_agextent_iter( + struct xreap_state *rs, + xfs_agblock_t agbno, + xfs_extlen_t *aglenp, + bool crosslinked) +{ + struct xfs_scrub *sc = rs->sc; + xfs_fsblock_t fsbno; + int error = 0; + + fsbno = XFS_AGB_TO_FSB(sc->mp, sc->sa.pag->pag_agno, agbno); + + /* + * If there are other rmappings, this block is cross linked and must + * not be freed. Remove the reverse mapping and move on. Otherwise, + * we were the only owner of the block, so free the extent, which will + * also remove the rmap. + * + * XXX: XFS doesn't support detecting the case where a single block + * metadata structure is crosslinked with a multi-block structure + * because the buffer cache doesn't detect aliasing problems, so we + * can't fix 100% of crosslinking problems (yet). The verifiers will + * blow on writeout, the filesystem will shut down, and the admin gets + * to run xfs_repair. + */ + if (crosslinked) { + trace_xreap_dispose_unmap_extent(sc->sa.pag, agbno, *aglenp); + + rs->force_roll = true; + return xfs_rmap_free(sc->tp, sc->sa.agf_bp, sc->sa.pag, agbno, + *aglenp, rs->oinfo); + } + + trace_xreap_dispose_free_extent(sc->sa.pag, agbno, *aglenp); + + /* + * Invalidate as many buffers as we can, starting at agbno. If this + * function sets *aglenp to zero, the transaction is full of logged + * buffer invalidations, so we need to return early so that we can + * roll and retry. + */ + xreap_agextent_binval(rs, agbno, aglenp); + if (*aglenp == 0) { + ASSERT(xreap_want_roll(rs)); + return 0; + } + + /* Put blocks back on the AGFL one at a time. */ + if (rs->resv == XFS_AG_RESV_AGFL) { + ASSERT(*aglenp == 1); + error = xreap_put_freelist(sc, agbno); + if (error) + return error; + + rs->force_roll = true; + return 0; + } + + /* + * Use deferred frees to get rid of the old btree blocks to try to + * minimize the window in which we could crash and lose the old blocks. + */ + error = __xfs_free_extent_later(sc->tp, fsbno, *aglenp, rs->oinfo, + rs->resv, true); + if (error) + return error; + + rs->deferred++; + return 0; +} + +/* + * Break an AG metadata extent into sub-extents by fate (crosslinked, not + * crosslinked), and dispose of each sub-extent separately. + */ +STATIC int +xreap_agmeta_extent( + uint64_t fsbno, + uint64_t len, + void *priv) +{ + struct xreap_state *rs = priv; + struct xfs_scrub *sc = rs->sc; + xfs_agblock_t agbno = fsbno; + xfs_agblock_t agbno_next = agbno + len; + int error = 0; + + ASSERT(len <= XFS_MAX_BMBT_EXTLEN); + ASSERT(sc->ip == NULL); + + while (agbno < agbno_next) { + xfs_extlen_t aglen; + bool crosslinked; + + error = xreap_agextent_select(rs, agbno, agbno_next, + &crosslinked, &aglen); + if (error) + return error; + + error = xreap_agextent_iter(rs, agbno, &aglen, crosslinked); + if (error) + return error; + + if (xreap_want_defer_finish(rs)) { + error = xrep_defer_finish(sc); + if (error) + return error; + xreap_defer_finish_reset(rs); + } else if (xreap_want_roll(rs)) { + error = xrep_roll_ag_trans(sc); + if (error) + return error; + xreap_reset(rs); + } + + agbno += aglen; + } + + return 0; +} + +/* Dispose of every block of every AG metadata extent in the bitmap. */ +int +xrep_reap_agblocks( + struct xfs_scrub *sc, + struct xagb_bitmap *bitmap, + const struct xfs_owner_info *oinfo, + enum xfs_ag_resv_type type) +{ + struct xreap_state rs = { + .sc = sc, + .oinfo = oinfo, + .resv = type, + }; + int error; + + ASSERT(xfs_has_rmapbt(sc->mp)); + ASSERT(sc->ip == NULL); + + error = xagb_bitmap_walk(bitmap, xreap_agmeta_extent, &rs); + if (error) + return error; + + if (xreap_dirty(&rs)) + return xrep_defer_finish(sc); + + return 0; +} |