xfs: add the ability to reap entire inode forks
authorDarrick J. Wong <djwong@kernel.org>
Mon, 15 Apr 2024 21:54:30 +0000 (14:54 -0700)
committerDarrick J. Wong <djwong@kernel.org>
Mon, 15 Apr 2024 21:58:49 +0000 (14:58 -0700)
In preparation for supporting repair of indexed file-based metadata
(such as realtime bitmaps, directories, and extended attribute data),
add a function to reap the old blocks after a metadata repair finishes.
IOWs, this is an elaborate bunmapi call that deals with crosslinked
blocks by unmapping them without freeing them, and also scans for incore
buffers to invalidate.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
fs/xfs/scrub/reap.c
fs/xfs/scrub/reap.h
fs/xfs/scrub/trace.h

index 7ae6253395e72159c4839a0fe5cd985016aab269..01ceaa4efa16bf3478589999364ee64a3769aa16 100644 (file)
@@ -675,3 +675,375 @@ xrep_reap_fsblocks(
 
        return 0;
 }
+
+/*
+ * Metadata files are not supposed to share blocks with anything else.
+ * If blocks are shared, we remove the reverse mapping (thus reducing the
+ * crosslink factor); if blocks are not shared, we also need to free them.
+ *
+ * This first step determines the longest subset of the passed-in imap
+ * (starting at its beginning) that is either crosslinked or not crosslinked.
+ * The blockcount will be adjust down as needed.
+ */
+STATIC int
+xreap_bmapi_select(
+       struct xfs_scrub        *sc,
+       struct xfs_inode        *ip,
+       int                     whichfork,
+       struct xfs_bmbt_irec    *imap,
+       bool                    *crosslinked)
+{
+       struct xfs_owner_info   oinfo;
+       struct xfs_btree_cur    *cur;
+       xfs_filblks_t           len = 1;
+       xfs_agblock_t           bno;
+       xfs_agblock_t           agbno;
+       xfs_agblock_t           agbno_next;
+       int                     error;
+
+       agbno = XFS_FSB_TO_AGBNO(sc->mp, imap->br_startblock);
+       agbno_next = agbno + imap->br_blockcount;
+
+       cur = xfs_rmapbt_init_cursor(sc->mp, sc->tp, sc->sa.agf_bp,
+                       sc->sa.pag);
+
+       xfs_rmap_ino_owner(&oinfo, ip->i_ino, whichfork, imap->br_startoff);
+       error = xfs_rmap_has_other_keys(cur, agbno, 1, &oinfo, crosslinked);
+       if (error)
+               goto out_cur;
+
+       bno = agbno + 1;
+       while (bno < agbno_next) {
+               bool            also_crosslinked;
+
+               oinfo.oi_offset++;
+               error = xfs_rmap_has_other_keys(cur, bno, 1, &oinfo,
+                               &also_crosslinked);
+               if (error)
+                       goto out_cur;
+
+               if (also_crosslinked != *crosslinked)
+                       break;
+
+               len++;
+               bno++;
+       }
+
+       imap->br_blockcount = len;
+       trace_xreap_bmapi_select(sc->sa.pag, agbno, len, *crosslinked);
+out_cur:
+       xfs_btree_del_cursor(cur, error);
+       return error;
+}
+
+/*
+ * Decide if this buffer can be joined to a transaction.  This is true for most
+ * buffers, but there are two cases that we want to catch: large remote xattr
+ * value buffers are not logged and can overflow the buffer log item dirty
+ * bitmap size; and oversized cached buffers if things have really gone
+ * haywire.
+ */
+static inline bool
+xreap_buf_loggable(
+       const struct xfs_buf    *bp)
+{
+       int                     i;
+
+       for (i = 0; i < bp->b_map_count; i++) {
+               int             chunks;
+               int             map_size;
+
+               chunks = DIV_ROUND_UP(BBTOB(bp->b_maps[i].bm_len),
+                               XFS_BLF_CHUNK);
+               map_size = DIV_ROUND_UP(chunks, NBWORD);
+               if (map_size > XFS_BLF_DATAMAP_SIZE)
+                       return false;
+       }
+
+       return true;
+}
+
+/*
+ * Invalidate any buffers for this file mapping.  The @imap blockcount may be
+ * adjusted downward if we need to roll the transaction.
+ */
+STATIC int
+xreap_bmapi_binval(
+       struct xfs_scrub        *sc,
+       struct xfs_inode        *ip,
+       int                     whichfork,
+       struct xfs_bmbt_irec    *imap)
+{
+       struct xfs_mount        *mp = sc->mp;
+       struct xfs_perag        *pag = sc->sa.pag;
+       int                     bmap_flags = xfs_bmapi_aflag(whichfork);
+       xfs_fileoff_t           off;
+       xfs_fileoff_t           max_off;
+       xfs_extlen_t            scan_blocks;
+       xfs_agnumber_t          agno = sc->sa.pag->pag_agno;
+       xfs_agblock_t           bno;
+       xfs_agblock_t           agbno;
+       xfs_agblock_t           agbno_next;
+       unsigned int            invalidated = 0;
+       int                     error;
+
+       /*
+        * Avoid invalidating AG headers and post-EOFS blocks because we never
+        * own those.
+        */
+       agbno = bno = XFS_FSB_TO_AGBNO(sc->mp, imap->br_startblock);
+       agbno_next = agbno + imap->br_blockcount;
+       if (!xfs_verify_agbno(pag, agbno) ||
+           !xfs_verify_agbno(pag, agbno_next - 1))
+               return 0;
+
+       /*
+        * Buffers for file blocks can span multiple contiguous mappings.  This
+        * means that for each block in the mapping, there could exist an
+        * xfs_buf indexed by that block with any length up to the maximum
+        * buffer size (remote xattr values) or to the next hole in the fork.
+        * To set up our binval scan, first we need to figure out the location
+        * of the next hole.
+        */
+       off = imap->br_startoff + imap->br_blockcount;
+       max_off = off + xfs_attr3_rmt_blocks(mp, XFS_XATTR_SIZE_MAX);
+       while (off < max_off) {
+               struct xfs_bmbt_irec    hmap;
+               int                     nhmaps = 1;
+
+               error = xfs_bmapi_read(ip, off, max_off - off, &hmap,
+                               &nhmaps, bmap_flags);
+               if (error)
+                       return error;
+               if (nhmaps != 1 || hmap.br_startblock == DELAYSTARTBLOCK) {
+                       ASSERT(0);
+                       return -EFSCORRUPTED;
+               }
+
+               if (!xfs_bmap_is_real_extent(&hmap))
+                       break;
+
+               off = hmap.br_startoff + hmap.br_blockcount;
+       }
+       scan_blocks = off - imap->br_startoff;
+
+       trace_xreap_bmapi_binval_scan(sc, imap, scan_blocks);
+
+       /*
+        * If there are incore buffers for these blocks, invalidate them.  If
+        * we can't (try)lock the buffer we assume it's owned by someone else
+        * and leave it alone.  The buffer cache cannot detect aliasing, so
+        * employ nested loops to detect incore buffers of any plausible size.
+        */
+       while (bno < agbno_next) {
+               struct xrep_bufscan     scan = {
+                       .daddr          = XFS_AGB_TO_DADDR(mp, agno, bno),
+                       .max_sectors    = xrep_bufscan_max_sectors(mp,
+                                                               scan_blocks),
+                       .daddr_step     = XFS_FSB_TO_BB(mp, 1),
+               };
+               struct xfs_buf          *bp;
+
+               while ((bp = xrep_bufscan_advance(mp, &scan)) != NULL) {
+                       if (xreap_buf_loggable(bp)) {
+                               xfs_trans_bjoin(sc->tp, bp);
+                               xfs_trans_binval(sc->tp, bp);
+                       } else {
+                               xfs_buf_stale(bp);
+                               xfs_buf_relse(bp);
+                       }
+                       invalidated++;
+
+                       /*
+                        * Stop invalidating if we've hit the limit; we should
+                        * still have enough reservation left to free however
+                        * much of the mapping we've seen so far.
+                        */
+                       if (invalidated > XREAP_MAX_BINVAL) {
+                               imap->br_blockcount = agbno_next - bno;
+                               goto out;
+                       }
+               }
+
+               bno++;
+               scan_blocks--;
+       }
+
+out:
+       trace_xreap_bmapi_binval(sc->sa.pag, agbno, imap->br_blockcount);
+       return 0;
+}
+
+/*
+ * Dispose of as much of the beginning of this file fork mapping as possible.
+ * The number of blocks disposed of is returned in @imap->br_blockcount.
+ */
+STATIC int
+xrep_reap_bmapi_iter(
+       struct xfs_scrub                *sc,
+       struct xfs_inode                *ip,
+       int                             whichfork,
+       struct xfs_bmbt_irec            *imap,
+       bool                            crosslinked)
+{
+       int                             error;
+
+       if (crosslinked) {
+               /*
+                * If there are other rmappings, this block is cross linked and
+                * must not be freed.  Remove the reverse mapping, leave the
+                * buffer cache in its possibly confused state, and move on.
+                * We don't want to risk discarding valid data buffers from
+                * anybody else who thinks they own the block, even though that
+                * runs the risk of stale buffer warnings in the future.
+                */
+               trace_xreap_dispose_unmap_extent(sc->sa.pag,
+                               XFS_FSB_TO_AGBNO(sc->mp, imap->br_startblock),
+                               imap->br_blockcount);
+
+               /*
+                * Schedule removal of the mapping from the fork.  We use
+                * deferred log intents in this function to control the exact
+                * sequence of metadata updates.
+                */
+               xfs_bmap_unmap_extent(sc->tp, ip, whichfork, imap);
+               xfs_trans_mod_dquot_byino(sc->tp, ip, XFS_TRANS_DQ_BCOUNT,
+                               -(int64_t)imap->br_blockcount);
+               xfs_rmap_unmap_extent(sc->tp, ip, whichfork, imap);
+               return 0;
+       }
+
+       /*
+        * If the block is not crosslinked, we can invalidate all the incore
+        * buffers for the extent, and then free the extent.  This is a bit of
+        * a mess since we don't detect discontiguous buffers that are indexed
+        * by a block starting before the first block of the extent but overlap
+        * anyway.
+        */
+       trace_xreap_dispose_free_extent(sc->sa.pag,
+                       XFS_FSB_TO_AGBNO(sc->mp, imap->br_startblock),
+                       imap->br_blockcount);
+
+       /*
+        * Invalidate as many buffers as we can, starting at the beginning of
+        * this mapping.  If this function sets blockcount to zero, the
+        * transaction is full of logged buffer invalidations, so we need to
+        * return early so that we can roll and retry.
+        */
+       error = xreap_bmapi_binval(sc, ip, whichfork, imap);
+       if (error || imap->br_blockcount == 0)
+               return error;
+
+       /*
+        * Schedule removal of the mapping from the fork.  We use deferred log
+        * intents in this function to control the exact sequence of metadata
+        * updates.
+        */
+       xfs_bmap_unmap_extent(sc->tp, ip, whichfork, imap);
+       xfs_trans_mod_dquot_byino(sc->tp, ip, XFS_TRANS_DQ_BCOUNT,
+                       -(int64_t)imap->br_blockcount);
+       return xfs_free_extent_later(sc->tp, imap->br_startblock,
+                       imap->br_blockcount, NULL, XFS_AG_RESV_NONE, true);
+}
+
+/*
+ * Dispose of as much of this file extent as we can.  Upon successful return,
+ * the imap will reflect the mapping that was removed from the fork.
+ */
+STATIC int
+xreap_ifork_extent(
+       struct xfs_scrub                *sc,
+       struct xfs_inode                *ip,
+       int                             whichfork,
+       struct xfs_bmbt_irec            *imap)
+{
+       xfs_agnumber_t                  agno;
+       bool                            crosslinked;
+       int                             error;
+
+       ASSERT(sc->sa.pag == NULL);
+
+       trace_xreap_ifork_extent(sc, ip, whichfork, imap);
+
+       agno = XFS_FSB_TO_AGNO(sc->mp, imap->br_startblock);
+       sc->sa.pag = xfs_perag_get(sc->mp, agno);
+       if (!sc->sa.pag)
+               return -EFSCORRUPTED;
+
+       error = xfs_alloc_read_agf(sc->sa.pag, sc->tp, 0, &sc->sa.agf_bp);
+       if (error)
+               goto out_pag;
+
+       /*
+        * Decide the fate of the blocks at the beginning of the mapping, then
+        * update the mapping to use it with the unmap calls.
+        */
+       error = xreap_bmapi_select(sc, ip, whichfork, imap, &crosslinked);
+       if (error)
+               goto out_agf;
+
+       error = xrep_reap_bmapi_iter(sc, ip, whichfork, imap, crosslinked);
+       if (error)
+               goto out_agf;
+
+out_agf:
+       xfs_trans_brelse(sc->tp, sc->sa.agf_bp);
+       sc->sa.agf_bp = NULL;
+out_pag:
+       xfs_perag_put(sc->sa.pag);
+       sc->sa.pag = NULL;
+       return error;
+}
+
+/*
+ * Dispose of each block mapped to the given fork of the given file.  Callers
+ * must hold ILOCK_EXCL, and ip can only be sc->ip or sc->tempip.  The fork
+ * must not have any delalloc reservations.
+ */
+int
+xrep_reap_ifork(
+       struct xfs_scrub        *sc,
+       struct xfs_inode        *ip,
+       int                     whichfork)
+{
+       xfs_fileoff_t           off = 0;
+       int                     bmap_flags = xfs_bmapi_aflag(whichfork);
+       int                     error;
+
+       ASSERT(xfs_has_rmapbt(sc->mp));
+       ASSERT(ip == sc->ip || ip == sc->tempip);
+       ASSERT(whichfork == XFS_ATTR_FORK || !XFS_IS_REALTIME_INODE(ip));
+
+       while (off < XFS_MAX_FILEOFF) {
+               struct xfs_bmbt_irec    imap;
+               int                     nimaps = 1;
+
+               /* Read the next extent, skip past holes and delalloc. */
+               error = xfs_bmapi_read(ip, off, XFS_MAX_FILEOFF - off, &imap,
+                               &nimaps, bmap_flags);
+               if (error)
+                       return error;
+               if (nimaps != 1 || imap.br_startblock == DELAYSTARTBLOCK) {
+                       ASSERT(0);
+                       return -EFSCORRUPTED;
+               }
+
+               /*
+                * If this is a real space mapping, reap as much of it as we
+                * can in a single transaction.
+                */
+               if (xfs_bmap_is_real_extent(&imap)) {
+                       error = xreap_ifork_extent(sc, ip, whichfork, &imap);
+                       if (error)
+                               return error;
+
+                       error = xfs_defer_finish(&sc->tp);
+                       if (error)
+                               return error;
+               }
+
+               off = imap.br_startoff + imap.br_blockcount;
+       }
+
+       return 0;
+}
index bb09e21fcb1725a5a0a794b1470c5f4f45058f1b..3f2f1775e29db4e71734e786eb0dac2246cf087c 100644 (file)
@@ -13,6 +13,7 @@ int xrep_reap_agblocks(struct xfs_scrub *sc, struct xagb_bitmap *bitmap,
                const struct xfs_owner_info *oinfo, enum xfs_ag_resv_type type);
 int xrep_reap_fsblocks(struct xfs_scrub *sc, struct xfsb_bitmap *bitmap,
                const struct xfs_owner_info *oinfo);
+int xrep_reap_ifork(struct xfs_scrub *sc, struct xfs_inode *ip, int whichfork);
 
 /* Buffer cache scan context. */
 struct xrep_bufscan {
index 020b029b7988f4509b84cf3408bac82527aaf1ec..cbd70ecd30113c0e48f47af0aa8ec98f122a7aa9 100644 (file)
@@ -1539,6 +1539,7 @@ DEFINE_EVENT(xrep_extent_class, name, \
 DEFINE_REPAIR_EXTENT_EVENT(xreap_dispose_unmap_extent);
 DEFINE_REPAIR_EXTENT_EVENT(xreap_dispose_free_extent);
 DEFINE_REPAIR_EXTENT_EVENT(xreap_agextent_binval);
+DEFINE_REPAIR_EXTENT_EVENT(xreap_bmapi_binval);
 DEFINE_REPAIR_EXTENT_EVENT(xrep_agfl_insert);
 
 DECLARE_EVENT_CLASS(xrep_reap_find_class,
@@ -1572,6 +1573,7 @@ DEFINE_EVENT(xrep_reap_find_class, name, \
                 bool crosslinked), \
        TP_ARGS(pag, agbno, len, crosslinked))
 DEFINE_REPAIR_REAP_FIND_EVENT(xreap_agextent_select);
+DEFINE_REPAIR_REAP_FIND_EVENT(xreap_bmapi_select);
 
 DECLARE_EVENT_CLASS(xrep_rmap_class,
        TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno,
@@ -2312,6 +2314,67 @@ TRACE_EVENT(xrep_tempfile_create,
                  __entry->temp_inum)
 );
 
+TRACE_EVENT(xreap_ifork_extent,
+       TP_PROTO(struct xfs_scrub *sc, struct xfs_inode *ip, int whichfork,
+                const struct xfs_bmbt_irec *irec),
+       TP_ARGS(sc, ip, whichfork, irec),
+       TP_STRUCT__entry(
+               __field(dev_t, dev)
+               __field(xfs_ino_t, ino)
+               __field(int, whichfork)
+               __field(xfs_fileoff_t, fileoff)
+               __field(xfs_filblks_t, len)
+               __field(xfs_agnumber_t, agno)
+               __field(xfs_agblock_t, agbno)
+               __field(int, state)
+       ),
+       TP_fast_assign(
+               __entry->dev = sc->mp->m_super->s_dev;
+               __entry->ino = ip->i_ino;
+               __entry->whichfork = whichfork;
+               __entry->fileoff = irec->br_startoff;
+               __entry->len = irec->br_blockcount;
+               __entry->agno = XFS_FSB_TO_AGNO(sc->mp, irec->br_startblock);
+               __entry->agbno = XFS_FSB_TO_AGBNO(sc->mp, irec->br_startblock);
+               __entry->state = irec->br_state;
+       ),
+       TP_printk("dev %d:%d ip 0x%llx whichfork %s agno 0x%x agbno 0x%x fileoff 0x%llx fsbcount 0x%llx state 0x%x",
+                 MAJOR(__entry->dev), MINOR(__entry->dev),
+                 __entry->ino,
+                 __print_symbolic(__entry->whichfork, XFS_WHICHFORK_STRINGS),
+                 __entry->agno,
+                 __entry->agbno,
+                 __entry->fileoff,
+                 __entry->len,
+                 __entry->state)
+);
+
+TRACE_EVENT(xreap_bmapi_binval_scan,
+       TP_PROTO(struct xfs_scrub *sc, const struct xfs_bmbt_irec *irec,
+                xfs_extlen_t scan_blocks),
+       TP_ARGS(sc, irec, scan_blocks),
+       TP_STRUCT__entry(
+               __field(dev_t, dev)
+               __field(xfs_filblks_t, len)
+               __field(xfs_agnumber_t, agno)
+               __field(xfs_agblock_t, agbno)
+               __field(xfs_extlen_t, scan_blocks)
+       ),
+       TP_fast_assign(
+               __entry->dev = sc->mp->m_super->s_dev;
+               __entry->len = irec->br_blockcount;
+               __entry->agno = XFS_FSB_TO_AGNO(sc->mp, irec->br_startblock);
+               __entry->agbno = XFS_FSB_TO_AGBNO(sc->mp, irec->br_startblock);
+               __entry->scan_blocks = scan_blocks;
+       ),
+       TP_printk("dev %d:%d agno 0x%x agbno 0x%x fsbcount 0x%llx scan_blocks 0x%x",
+                 MAJOR(__entry->dev), MINOR(__entry->dev),
+                 __entry->agno,
+                 __entry->agbno,
+                 __entry->len,
+                 __entry->scan_blocks)
+);
+
 #endif /* IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR) */
 
 #endif /* _TRACE_XFS_SCRUB_TRACE_H */