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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
  * All Rights Reserved.
  */
 #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_bit.h"
 #include "xfs_mount.h"
 #include "xfs_trans.h"
 #include "xfs_buf_item.h"
 #include "xfs_trans_priv.h"
 #include "xfs_trace.h"
 #include "xfs_log.h"
 #include "xfs_log_priv.h"
 #include "xfs_log_recover.h"
 #include "xfs_error.h"
 #include "xfs_inode.h"
 #include "xfs_dir2.h"
 #include "xfs_quota.h"
 
 /*
  * This is the number of entries in the l_buf_cancel_table used during
  * recovery.
  */
 #define XLOG_BC_TABLE_SIZE  64
 
 #define XLOG_BUF_CANCEL_BUCKET(log, blkno) \
     ((log)->l_buf_cancel_table + ((uint64_t)blkno % XLOG_BC_TABLE_SIZE))
 
 /*
  * This structure is used during recovery to record the buf log items which
  * have been canceled and should not be replayed.
  */
 struct xfs_buf_cancel {
     xfs_daddr_t     bc_blkno;
     uint            bc_len;
     int         bc_refcount;
     struct list_head    bc_list;
 };
 
 static struct xfs_buf_cancel *
 xlog_find_buffer_cancelled(
     struct xlog     *log,
     xfs_daddr_t     blkno,
     uint            len)
 {
     struct list_head    *bucket;
     struct xfs_buf_cancel   *bcp;
 
     if (!log->l_buf_cancel_table)
         return NULL;
 
     bucket = XLOG_BUF_CANCEL_BUCKET(log, blkno);
     list_for_each_entry(bcp, bucket, bc_list) {
         if (bcp->bc_blkno == blkno && bcp->bc_len == len)
             return bcp;
     }
 
     return NULL;
 }
 
 static bool
 xlog_add_buffer_cancelled(
     struct xlog     *log,
     xfs_daddr_t     blkno,
     uint            len)
 {
     struct xfs_buf_cancel   *bcp;
 
     /*
      * If we find an existing cancel record, this indicates that the buffer
      * was cancelled multiple times.  To ensure that during pass 2 we keep
      * the record in the table until we reach its last occurrence in the
      * log, a reference count is kept to tell how many times we expect to
      * see this record during the second pass.
      */
     bcp = xlog_find_buffer_cancelled(log, blkno, len);
     if (bcp) {
         bcp->bc_refcount++;
         return false;
     }
 
     bcp = kmem_alloc(sizeof(struct xfs_buf_cancel), 0);
     bcp->bc_blkno = blkno;
     bcp->bc_len = len;
     bcp->bc_refcount = 1;
     list_add_tail(&bcp->bc_list, XLOG_BUF_CANCEL_BUCKET(log, blkno));
     return true;
 }
 
 /*
  * Check if there is and entry for blkno, len in the buffer cancel record table.
  */
 bool
 xlog_is_buffer_cancelled(
     struct xlog     *log,
     xfs_daddr_t     blkno,
     uint            len)
 {
     return xlog_find_buffer_cancelled(log, blkno, len) != NULL;
 }
 
 /*
  * Check if there is and entry for blkno, len in the buffer cancel record table,
  * and decremented the reference count on it if there is one.
  *
  * Remove the cancel record once the refcount hits zero, so that if the same
  * buffer is re-used again after its last cancellation we actually replay the
  * changes made at that point.
  */
 static bool
 xlog_put_buffer_cancelled(
     struct xlog     *log,
     xfs_daddr_t     blkno,
     uint            len)
 {
     struct xfs_buf_cancel   *bcp;
 
     bcp = xlog_find_buffer_cancelled(log, blkno, len);
     if (!bcp) {
         ASSERT(0);
         return false;
     }
 
     if (--bcp->bc_refcount == 0) {
         list_del(&bcp->bc_list);
         kmem_free(bcp);
     }
     return true;
 }
 
 /* log buffer item recovery */
 
 /*
  * Sort buffer items for log recovery.  Most buffer items should end up on the
  * buffer list and are recovered first, with the following exceptions:
  *
  * 1. XFS_BLF_CANCEL buffers must be processed last because some log items
  *    might depend on the incor ecancellation record, and replaying a cancelled
  *    buffer item can remove the incore record.
  *
  * 2. XFS_BLF_INODE_BUF buffers are handled after most regular items so that
  *    we replay di_next_unlinked only after flushing the inode 'free' state
  *    to the inode buffer.
  *
  * See xlog_recover_reorder_trans for more details.
  */
 STATIC enum xlog_recover_reorder
 xlog_recover_buf_reorder(
     struct xlog_recover_item    *item)
 {
     struct xfs_buf_log_format   *buf_f = item->ri_buf[0].i_addr;
 
     if (buf_f->blf_flags & XFS_BLF_CANCEL)
         return XLOG_REORDER_CANCEL_LIST;
     if (buf_f->blf_flags & XFS_BLF_INODE_BUF)
         return XLOG_REORDER_INODE_BUFFER_LIST;
     return XLOG_REORDER_BUFFER_LIST;
 }
 
 STATIC void
 xlog_recover_buf_ra_pass2(
     struct xlog                     *log,
     struct xlog_recover_item        *item)
 {
     struct xfs_buf_log_format   *buf_f = item->ri_buf[0].i_addr;
 
     xlog_buf_readahead(log, buf_f->blf_blkno, buf_f->blf_len, NULL);
 }
 
 /*
  * Build up the table of buf cancel records so that we don't replay cancelled
  * data in the second pass.
  */
 static int
 xlog_recover_buf_commit_pass1(
     struct xlog         *log,
     struct xlog_recover_item    *item)
 {
     struct xfs_buf_log_format   *bf = item->ri_buf[0].i_addr;
 
     if (!xfs_buf_log_check_iovec(&item->ri_buf[0])) {
         xfs_err(log->l_mp, "bad buffer log item size (%d)",
                 item->ri_buf[0].i_len);
         return -EFSCORRUPTED;
     }
 
     if (!(bf->blf_flags & XFS_BLF_CANCEL))
         trace_xfs_log_recover_buf_not_cancel(log, bf);
     else if (xlog_add_buffer_cancelled(log, bf->blf_blkno, bf->blf_len))
         trace_xfs_log_recover_buf_cancel_add(log, bf);
     else
         trace_xfs_log_recover_buf_cancel_ref_inc(log, bf);
     return 0;
 }
 
 /*
  * Validate the recovered buffer is of the correct type and attach the
  * appropriate buffer operations to them for writeback. Magic numbers are in a
  * few places:
  *  the first 16 bits of the buffer (inode buffer, dquot buffer),
  *  the first 32 bits of the buffer (most blocks),
  *  inside a struct xfs_da_blkinfo at the start of the buffer.
  */
 static void
 xlog_recover_validate_buf_type(
     struct xfs_mount        *mp,
     struct xfs_buf          *bp,
     struct xfs_buf_log_format   *buf_f,
     xfs_lsn_t           current_lsn)
 {
     struct xfs_da_blkinfo       *info = bp->b_addr;
     uint32_t            magic32;
     uint16_t            magic16;
     uint16_t            magicda;
     char                *warnmsg = NULL;
 
     /*
      * We can only do post recovery validation on items on CRC enabled
      * fielsystems as we need to know when the buffer was written to be able
      * to determine if we should have replayed the item. If we replay old
      * metadata over a newer buffer, then it will enter a temporarily
      * inconsistent state resulting in verification failures. Hence for now
      * just avoid the verification stage for non-crc filesystems
      */
     if (!xfs_has_crc(mp))
         return;
 
     magic32 = be32_to_cpu(*(__be32 *)bp->b_addr);
     magic16 = be16_to_cpu(*(__be16*)bp->b_addr);
     magicda = be16_to_cpu(info->magic);
     switch (xfs_blft_from_flags(buf_f)) {
     case XFS_BLFT_BTREE_BUF:
         switch (magic32) {
         case XFS_ABTB_CRC_MAGIC:
         case XFS_ABTB_MAGIC:
             bp->b_ops = &xfs_bnobt_buf_ops;
             break;
         case XFS_ABTC_CRC_MAGIC:
         case XFS_ABTC_MAGIC:
             bp->b_ops = &xfs_cntbt_buf_ops;
             break;
         case XFS_IBT_CRC_MAGIC:
         case XFS_IBT_MAGIC:
             bp->b_ops = &xfs_inobt_buf_ops;
             break;
         case XFS_FIBT_CRC_MAGIC:
         case XFS_FIBT_MAGIC:
             bp->b_ops = &xfs_finobt_buf_ops;
             break;
         case XFS_BMAP_CRC_MAGIC:
         case XFS_BMAP_MAGIC:
             bp->b_ops = &xfs_bmbt_buf_ops;
             break;
         case XFS_RMAP_CRC_MAGIC:
             bp->b_ops = &xfs_rmapbt_buf_ops;
             break;
         case XFS_REFC_CRC_MAGIC:
             bp->b_ops = &xfs_refcountbt_buf_ops;
             break;
         default:
             warnmsg = "Bad btree block magic!";
             break;
         }
         break;
     case XFS_BLFT_AGF_BUF:
         if (magic32 != XFS_AGF_MAGIC) {
             warnmsg = "Bad AGF block magic!";
             break;
         }
         bp->b_ops = &xfs_agf_buf_ops;
         break;
     case XFS_BLFT_AGFL_BUF:
         if (magic32 != XFS_AGFL_MAGIC) {
             warnmsg = "Bad AGFL block magic!";
             break;
         }
         bp->b_ops = &xfs_agfl_buf_ops;
         break;
     case XFS_BLFT_AGI_BUF:
         if (magic32 != XFS_AGI_MAGIC) {
             warnmsg = "Bad AGI block magic!";
             break;
         }
         bp->b_ops = &xfs_agi_buf_ops;
         break;
     case XFS_BLFT_UDQUOT_BUF:
     case XFS_BLFT_PDQUOT_BUF:
     case XFS_BLFT_GDQUOT_BUF:
 #ifdef CONFIG_XFS_QUOTA
         if (magic16 != XFS_DQUOT_MAGIC) {
             warnmsg = "Bad DQUOT block magic!";
             break;
         }
         bp->b_ops = &xfs_dquot_buf_ops;
 #else
         xfs_alert(mp,
     "Trying to recover dquots without QUOTA support built in!");
         ASSERT(0);
 #endif
         break;
     case XFS_BLFT_DINO_BUF:
         if (magic16 != XFS_DINODE_MAGIC) {
             warnmsg = "Bad INODE block magic!";
             break;
         }
         bp->b_ops = &xfs_inode_buf_ops;
         break;
     case XFS_BLFT_SYMLINK_BUF:
         if (magic32 != XFS_SYMLINK_MAGIC) {
             warnmsg = "Bad symlink block magic!";
             break;
         }
         bp->b_ops = &xfs_symlink_buf_ops;
         break;
     case XFS_BLFT_DIR_BLOCK_BUF:
         if (magic32 != XFS_DIR2_BLOCK_MAGIC &&
             magic32 != XFS_DIR3_BLOCK_MAGIC) {
             warnmsg = "Bad dir block magic!";
             break;
         }
         bp->b_ops = &xfs_dir3_block_buf_ops;
         break;
     case XFS_BLFT_DIR_DATA_BUF:
         if (magic32 != XFS_DIR2_DATA_MAGIC &&
             magic32 != XFS_DIR3_DATA_MAGIC) {
             warnmsg = "Bad dir data magic!";
             break;
         }
         bp->b_ops = &xfs_dir3_data_buf_ops;
         break;
     case XFS_BLFT_DIR_FREE_BUF:
         if (magic32 != XFS_DIR2_FREE_MAGIC &&
             magic32 != XFS_DIR3_FREE_MAGIC) {
             warnmsg = "Bad dir3 free magic!";
             break;
         }
         bp->b_ops = &xfs_dir3_free_buf_ops;
         break;
     case XFS_BLFT_DIR_LEAF1_BUF:
         if (magicda != XFS_DIR2_LEAF1_MAGIC &&
             magicda != XFS_DIR3_LEAF1_MAGIC) {
             warnmsg = "Bad dir leaf1 magic!";
             break;
         }
         bp->b_ops = &xfs_dir3_leaf1_buf_ops;
         break;
     case XFS_BLFT_DIR_LEAFN_BUF:
         if (magicda != XFS_DIR2_LEAFN_MAGIC &&
             magicda != XFS_DIR3_LEAFN_MAGIC) {
             warnmsg = "Bad dir leafn magic!";
             break;
         }
         bp->b_ops = &xfs_dir3_leafn_buf_ops;
         break;
     case XFS_BLFT_DA_NODE_BUF:
         if (magicda != XFS_DA_NODE_MAGIC &&
             magicda != XFS_DA3_NODE_MAGIC) {
             warnmsg = "Bad da node magic!";
             break;
         }
         bp->b_ops = &xfs_da3_node_buf_ops;
         break;
     case XFS_BLFT_ATTR_LEAF_BUF:
         if (magicda != XFS_ATTR_LEAF_MAGIC &&
             magicda != XFS_ATTR3_LEAF_MAGIC) {
             warnmsg = "Bad attr leaf magic!";
             break;
         }
         bp->b_ops = &xfs_attr3_leaf_buf_ops;
         break;
     case XFS_BLFT_ATTR_RMT_BUF:
         if (magic32 != XFS_ATTR3_RMT_MAGIC) {
             warnmsg = "Bad attr remote magic!";
             break;
         }
         bp->b_ops = &xfs_attr3_rmt_buf_ops;
         break;
     case XFS_BLFT_SB_BUF:
         if (magic32 != XFS_SB_MAGIC) {
             warnmsg = "Bad SB block magic!";
             break;
         }
         bp->b_ops = &xfs_sb_buf_ops;
         break;
 #ifdef CONFIG_XFS_RT
     case XFS_BLFT_RTBITMAP_BUF:
     case XFS_BLFT_RTSUMMARY_BUF:
         /* no magic numbers for verification of RT buffers */
         bp->b_ops = &xfs_rtbuf_ops;
         break;
 #endif /* CONFIG_XFS_RT */
     default:
         xfs_warn(mp, "Unknown buffer type %d!",
              xfs_blft_from_flags(buf_f));
         break;
     }
 
     /*
      * Nothing else to do in the case of a NULL current LSN as this means
      * the buffer is more recent than the change in the log and will be
      * skipped.
      */
     if (current_lsn == NULLCOMMITLSN)
         return;
 
     if (warnmsg) {
         xfs_warn(mp, warnmsg);
         ASSERT(0);
     }
 
     /*
      * We must update the metadata LSN of the buffer as it is written out to
      * ensure that older transactions never replay over this one and corrupt
      * the buffer. This can occur if log recovery is interrupted at some
      * point after the current transaction completes, at which point a
      * subsequent mount starts recovery from the beginning.
      *
      * Write verifiers update the metadata LSN from log items attached to
      * the buffer. Therefore, initialize a bli purely to carry the LSN to
      * the verifier.
      */
     if (bp->b_ops) {
         struct xfs_buf_log_item *bip;
 
         bp->b_flags |= _XBF_LOGRECOVERY;
         xfs_buf_item_init(bp, mp);
         bip = bp->b_log_item;
         bip->bli_item.li_lsn = current_lsn;
     }
 }
 
 /*
  * Perform a 'normal' buffer recovery.  Each logged region of the
  * buffer should be copied over the corresponding region in the
  * given buffer.  The bitmap in the buf log format structure indicates
  * where to place the logged data.
  */
 STATIC void
 xlog_recover_do_reg_buffer(
     struct xfs_mount        *mp,
     struct xlog_recover_item    *item,
     struct xfs_buf          *bp,
     struct xfs_buf_log_format   *buf_f,
     xfs_lsn_t           current_lsn)
 {
     int         i;
     int         bit;
     int         nbits;
     xfs_failaddr_t      fa;
     const size_t        size_disk_dquot = sizeof(struct xfs_disk_dquot);
 
     trace_xfs_log_recover_buf_reg_buf(mp->m_log, buf_f);
 
     bit = 0;
     i = 1;  /* 0 is the buf format structure */
     while (1) {
         bit = xfs_next_bit(buf_f->blf_data_map,
                    buf_f->blf_map_size, bit);
         if (bit == -1)
             break;
         nbits = xfs_contig_bits(buf_f->blf_data_map,
                     buf_f->blf_map_size, bit);
         ASSERT(nbits > 0);
         ASSERT(item->ri_buf[i].i_addr != NULL);
         ASSERT(item->ri_buf[i].i_len % XFS_BLF_CHUNK == 0);
         ASSERT(BBTOB(bp->b_length) >=
                ((uint)bit << XFS_BLF_SHIFT) + (nbits << XFS_BLF_SHIFT));
 
         /*
          * The dirty regions logged in the buffer, even though
          * contiguous, may span multiple chunks. This is because the
          * dirty region may span a physical page boundary in a buffer
          * and hence be split into two separate vectors for writing into
          * the log. Hence we need to trim nbits back to the length of
          * the current region being copied out of the log.
          */
         if (item->ri_buf[i].i_len < (nbits << XFS_BLF_SHIFT))
             nbits = item->ri_buf[i].i_len >> XFS_BLF_SHIFT;
 
         /*
          * Do a sanity check if this is a dquot buffer. Just checking
          * the first dquot in the buffer should do. XXXThis is
          * probably a good thing to do for other buf types also.
          */
         fa = NULL;
         if (buf_f->blf_flags &
            (XFS_BLF_UDQUOT_BUF|XFS_BLF_PDQUOT_BUF|XFS_BLF_GDQUOT_BUF)) {
             if (item->ri_buf[i].i_addr == NULL) {
                 xfs_alert(mp,
                     "XFS: NULL dquot in %s.", __func__);
                 goto next;
             }
             if (item->ri_buf[i].i_len < size_disk_dquot) {
                 xfs_alert(mp,
                     "XFS: dquot too small (%d) in %s.",
                     item->ri_buf[i].i_len, __func__);
                 goto next;
             }
             fa = xfs_dquot_verify(mp, item->ri_buf[i].i_addr, -1);
             if (fa) {
                 xfs_alert(mp,
     "dquot corrupt at %pS trying to replay into block 0x%llx",
                     fa, xfs_buf_daddr(bp));
                 goto next;
             }
         }
 
         memcpy(xfs_buf_offset(bp,
             (uint)bit << XFS_BLF_SHIFT),    /* dest */
             item->ri_buf[i].i_addr,     /* source */
             nbits<<XFS_BLF_SHIFT);      /* length */
  next:
         i++;
         bit += nbits;
     }
 
     /* Shouldn't be any more regions */
     ASSERT(i == item->ri_total);
 
     xlog_recover_validate_buf_type(mp, bp, buf_f, current_lsn);
 }
 
 /*
  * Perform a dquot buffer recovery.
  * Simple algorithm: if we have found a QUOTAOFF log item of the same type
  * (ie. USR or GRP), then just toss this buffer away; don't recover it.
  * Else, treat it as a regular buffer and do recovery.
  *
  * Return false if the buffer was tossed and true if we recovered the buffer to
  * indicate to the caller if the buffer needs writing.
  */
 STATIC bool
 xlog_recover_do_dquot_buffer(
     struct xfs_mount        *mp,
     struct xlog         *log,
     struct xlog_recover_item    *item,
     struct xfs_buf          *bp,
     struct xfs_buf_log_format   *buf_f)
 {
     uint            type;
 
     trace_xfs_log_recover_buf_dquot_buf(log, buf_f);
 
     /*
      * Filesystems are required to send in quota flags at mount time.
      */
     if (!mp->m_qflags)
         return false;
 
     type = 0;
     if (buf_f->blf_flags & XFS_BLF_UDQUOT_BUF)
         type |= XFS_DQTYPE_USER;
     if (buf_f->blf_flags & XFS_BLF_PDQUOT_BUF)
         type |= XFS_DQTYPE_PROJ;
     if (buf_f->blf_flags & XFS_BLF_GDQUOT_BUF)
         type |= XFS_DQTYPE_GROUP;
     /*
      * This type of quotas was turned off, so ignore this buffer
      */
     if (log->l_quotaoffs_flag & type)
         return false;
 
     xlog_recover_do_reg_buffer(mp, item, bp, buf_f, NULLCOMMITLSN);
     return true;
 }
 
 /*
  * Perform recovery for a buffer full of inodes.  In these buffers, the only
  * data which should be recovered is that which corresponds to the
  * di_next_unlinked pointers in the on disk inode structures.  The rest of the
  * data for the inodes is always logged through the inodes themselves rather
  * than the inode buffer and is recovered in xlog_recover_inode_pass2().
  *
  * The only time when buffers full of inodes are fully recovered is when the
  * buffer is full of newly allocated inodes.  In this case the buffer will
  * not be marked as an inode buffer and so will be sent to
  * xlog_recover_do_reg_buffer() below during recovery.
  */
 STATIC int
 xlog_recover_do_inode_buffer(
     struct xfs_mount        *mp,
     struct xlog_recover_item    *item,
     struct xfs_buf          *bp,
     struct xfs_buf_log_format   *buf_f)
 {
     int             i;
     int             item_index = 0;
     int             bit = 0;
     int             nbits = 0;
     int             reg_buf_offset = 0;
     int             reg_buf_bytes = 0;
     int             next_unlinked_offset;
     int             inodes_per_buf;
     xfs_agino_t         *logged_nextp;
     xfs_agino_t         *buffer_nextp;
 
     trace_xfs_log_recover_buf_inode_buf(mp->m_log, buf_f);
 
     /*
      * Post recovery validation only works properly on CRC enabled
      * filesystems.
      */
     if (xfs_has_crc(mp))
         bp->b_ops = &xfs_inode_buf_ops;
 
     inodes_per_buf = BBTOB(bp->b_length) >> mp->m_sb.sb_inodelog;
     for (i = 0; i < inodes_per_buf; i++) {
         next_unlinked_offset = (i * mp->m_sb.sb_inodesize) +
             offsetof(struct xfs_dinode, di_next_unlinked);
 
         while (next_unlinked_offset >=
                (reg_buf_offset + reg_buf_bytes)) {
             /*
              * The next di_next_unlinked field is beyond
              * the current logged region.  Find the next
              * logged region that contains or is beyond
              * the current di_next_unlinked field.
              */
             bit += nbits;
             bit = xfs_next_bit(buf_f->blf_data_map,
                        buf_f->blf_map_size, bit);
 
             /*
              * If there are no more logged regions in the
              * buffer, then we're done.
              */
             if (bit == -1)
                 return 0;
 
             nbits = xfs_contig_bits(buf_f->blf_data_map,
                         buf_f->blf_map_size, bit);
             ASSERT(nbits > 0);
             reg_buf_offset = bit << XFS_BLF_SHIFT;
             reg_buf_bytes = nbits << XFS_BLF_SHIFT;
             item_index++;
         }
 
         /*
          * If the current logged region starts after the current
          * di_next_unlinked field, then move on to the next
          * di_next_unlinked field.
          */
         if (next_unlinked_offset < reg_buf_offset)
             continue;
 
         ASSERT(item->ri_buf[item_index].i_addr != NULL);
         ASSERT((item->ri_buf[item_index].i_len % XFS_BLF_CHUNK) == 0);
         ASSERT((reg_buf_offset + reg_buf_bytes) <= BBTOB(bp->b_length));
 
         /*
          * The current logged region contains a copy of the
          * current di_next_unlinked field.  Extract its value
          * and copy it to the buffer copy.
          */
         logged_nextp = item->ri_buf[item_index].i_addr +
                 next_unlinked_offset - reg_buf_offset;
         if (XFS_IS_CORRUPT(mp, *logged_nextp == 0)) {
             xfs_alert(mp,
         "Bad inode buffer log record (ptr = "PTR_FMT", bp = "PTR_FMT"). "
         "Trying to replay bad (0) inode di_next_unlinked field.",
                 item, bp);
             return -EFSCORRUPTED;
         }
 
         buffer_nextp = xfs_buf_offset(bp, next_unlinked_offset);
         *buffer_nextp = *logged_nextp;
 
         /*
          * If necessary, recalculate the CRC in the on-disk inode. We
          * have to leave the inode in a consistent state for whoever
          * reads it next....
          */
         xfs_dinode_calc_crc(mp,
                 xfs_buf_offset(bp, i * mp->m_sb.sb_inodesize));
 
     }
 
     return 0;
 }
 
 /*
  * V5 filesystems know the age of the buffer on disk being recovered. We can
  * have newer objects on disk than we are replaying, and so for these cases we
  * don't want to replay the current change as that will make the buffer contents
  * temporarily invalid on disk.
  *
  * The magic number might not match the buffer type we are going to recover
  * (e.g. reallocated blocks), so we ignore the xfs_buf_log_format flags.  Hence
  * extract the LSN of the existing object in the buffer based on it's current
  * magic number.  If we don't recognise the magic number in the buffer, then
  * return a LSN of -1 so that the caller knows it was an unrecognised block and
  * so can recover the buffer.
  *
  * Note: we cannot rely solely on magic number matches to determine that the
  * buffer has a valid LSN - we also need to verify that it belongs to this
  * filesystem, so we need to extract the object's LSN and compare it to that
  * which we read from the superblock. If the UUIDs don't match, then we've got a
  * stale metadata block from an old filesystem instance that we need to recover
  * over the top of.
  */
 static xfs_lsn_t
 xlog_recover_get_buf_lsn(
     struct xfs_mount    *mp,
     struct xfs_buf      *bp,
     struct xfs_buf_log_format *buf_f)
 {
     uint32_t        magic32;
     uint16_t        magic16;
     uint16_t        magicda;
     void            *blk = bp->b_addr;
     uuid_t          *uuid;
     xfs_lsn_t       lsn = -1;
     uint16_t        blft;
 
     /* v4 filesystems always recover immediately */
     if (!xfs_has_crc(mp))
         goto recover_immediately;
 
     /*
      * realtime bitmap and summary file blocks do not have magic numbers or
      * UUIDs, so we must recover them immediately.
      */
     blft = xfs_blft_from_flags(buf_f);
     if (blft == XFS_BLFT_RTBITMAP_BUF || blft == XFS_BLFT_RTSUMMARY_BUF)
         goto recover_immediately;
 
     magic32 = be32_to_cpu(*(__be32 *)blk);
     switch (magic32) {
     case XFS_ABTB_CRC_MAGIC:
     case XFS_ABTC_CRC_MAGIC:
     case XFS_ABTB_MAGIC:
     case XFS_ABTC_MAGIC:
     case XFS_RMAP_CRC_MAGIC:
     case XFS_REFC_CRC_MAGIC:
     case XFS_FIBT_CRC_MAGIC:
     case XFS_FIBT_MAGIC:
     case XFS_IBT_CRC_MAGIC:
     case XFS_IBT_MAGIC: {
         struct xfs_btree_block *btb = blk;
 
         lsn = be64_to_cpu(btb->bb_u.s.bb_lsn);
         uuid = &btb->bb_u.s.bb_uuid;
         break;
     }
     case XFS_BMAP_CRC_MAGIC:
     case XFS_BMAP_MAGIC: {
         struct xfs_btree_block *btb = blk;
 
         lsn = be64_to_cpu(btb->bb_u.l.bb_lsn);
         uuid = &btb->bb_u.l.bb_uuid;
         break;
     }
     case XFS_AGF_MAGIC:
         lsn = be64_to_cpu(((struct xfs_agf *)blk)->agf_lsn);
         uuid = &((struct xfs_agf *)blk)->agf_uuid;
         break;
     case XFS_AGFL_MAGIC:
         lsn = be64_to_cpu(((struct xfs_agfl *)blk)->agfl_lsn);
         uuid = &((struct xfs_agfl *)blk)->agfl_uuid;
         break;
     case XFS_AGI_MAGIC:
         lsn = be64_to_cpu(((struct xfs_agi *)blk)->agi_lsn);
         uuid = &((struct xfs_agi *)blk)->agi_uuid;
         break;
     case XFS_SYMLINK_MAGIC:
         lsn = be64_to_cpu(((struct xfs_dsymlink_hdr *)blk)->sl_lsn);
         uuid = &((struct xfs_dsymlink_hdr *)blk)->sl_uuid;
         break;
     case XFS_DIR3_BLOCK_MAGIC:
     case XFS_DIR3_DATA_MAGIC:
     case XFS_DIR3_FREE_MAGIC:
         lsn = be64_to_cpu(((struct xfs_dir3_blk_hdr *)blk)->lsn);
         uuid = &((struct xfs_dir3_blk_hdr *)blk)->uuid;
         break;
     case XFS_ATTR3_RMT_MAGIC:
         /*
          * Remote attr blocks are written synchronously, rather than
          * being logged. That means they do not contain a valid LSN
          * (i.e. transactionally ordered) in them, and hence any time we
          * see a buffer to replay over the top of a remote attribute
          * block we should simply do so.
          */
         goto recover_immediately;
     case XFS_SB_MAGIC:
         /*
          * superblock uuids are magic. We may or may not have a
          * sb_meta_uuid on disk, but it will be set in the in-core
          * superblock. We set the uuid pointer for verification
          * according to the superblock feature mask to ensure we check
          * the relevant UUID in the superblock.
          */
         lsn = be64_to_cpu(((struct xfs_dsb *)blk)->sb_lsn);
         if (xfs_has_metauuid(mp))
             uuid = &((struct xfs_dsb *)blk)->sb_meta_uuid;
         else
             uuid = &((struct xfs_dsb *)blk)->sb_uuid;
         break;
     default:
         break;
     }
 
     if (lsn != (xfs_lsn_t)-1) {
         if (!uuid_equal(&mp->m_sb.sb_meta_uuid, uuid))
             goto recover_immediately;
         return lsn;
     }
 
     magicda = be16_to_cpu(((struct xfs_da_blkinfo *)blk)->magic);
     switch (magicda) {
     case XFS_DIR3_LEAF1_MAGIC:
     case XFS_DIR3_LEAFN_MAGIC:
     case XFS_ATTR3_LEAF_MAGIC:
     case XFS_DA3_NODE_MAGIC:
         lsn = be64_to_cpu(((struct xfs_da3_blkinfo *)blk)->lsn);
         uuid = &((struct xfs_da3_blkinfo *)blk)->uuid;
         break;
     default:
         break;
     }
 
     if (lsn != (xfs_lsn_t)-1) {
         if (!uuid_equal(&mp->m_sb.sb_meta_uuid, uuid))
             goto recover_immediately;
         return lsn;
     }
 
     /*
      * We do individual object checks on dquot and inode buffers as they
      * have their own individual LSN records. Also, we could have a stale
      * buffer here, so we have to at least recognise these buffer types.
      *
      * A notd complexity here is inode unlinked list processing - it logs
      * the inode directly in the buffer, but we don't know which inodes have
      * been modified, and there is no global buffer LSN. Hence we need to
      * recover all inode buffer types immediately. This problem will be
      * fixed by logical logging of the unlinked list modifications.
      */
     magic16 = be16_to_cpu(*(__be16 *)blk);
     switch (magic16) {
     case XFS_DQUOT_MAGIC:
     case XFS_DINODE_MAGIC:
         goto recover_immediately;
     default:
         break;
     }
 
     /* unknown buffer contents, recover immediately */
 
 recover_immediately:
     return (xfs_lsn_t)-1;
 
 }
 
 /*
  * This routine replays a modification made to a buffer at runtime.
  * There are actually two types of buffer, regular and inode, which
  * are handled differently.  Inode buffers are handled differently
  * in that we only recover a specific set of data from them, namely
  * the inode di_next_unlinked fields.  This is because all other inode
  * data is actually logged via inode records and any data we replay
  * here which overlaps that may be stale.
  *
  * When meta-data buffers are freed at run time we log a buffer item
  * with the XFS_BLF_CANCEL bit set to indicate that previous copies
  * of the buffer in the log should not be replayed at recovery time.
  * This is so that if the blocks covered by the buffer are reused for
  * file data before we crash we don't end up replaying old, freed
  * meta-data into a user's file.
  *
  * To handle the cancellation of buffer log items, we make two passes
  * over the log during recovery.  During the first we build a table of
  * those buffers which have been cancelled, and during the second we
  * only replay those buffers which do not have corresponding cancel
  * records in the table.  See xlog_recover_buf_pass[1,2] above
  * for more details on the implementation of the table of cancel records.
  */
 STATIC int
 xlog_recover_buf_commit_pass2(
     struct xlog         *log,
     struct list_head        *buffer_list,
     struct xlog_recover_item    *item,
     xfs_lsn_t           current_lsn)
 {
     struct xfs_buf_log_format   *buf_f = item->ri_buf[0].i_addr;
     struct xfs_mount        *mp = log->l_mp;
     struct xfs_buf          *bp;
     int             error;
     uint                buf_flags;
     xfs_lsn_t           lsn;
 
     /*
      * In this pass we only want to recover all the buffers which have
      * not been cancelled and are not cancellation buffers themselves.
      */
     if (buf_f->blf_flags & XFS_BLF_CANCEL) {
         if (xlog_put_buffer_cancelled(log, buf_f->blf_blkno,
                 buf_f->blf_len))
             goto cancelled;
     } else {
 
         if (xlog_is_buffer_cancelled(log, buf_f->blf_blkno,
                 buf_f->blf_len))
             goto cancelled;
     }
 
     trace_xfs_log_recover_buf_recover(log, buf_f);
 
     buf_flags = 0;
     if (buf_f->blf_flags & XFS_BLF_INODE_BUF)
         buf_flags |= XBF_UNMAPPED;
 
     error = xfs_buf_read(mp->m_ddev_targp, buf_f->blf_blkno, buf_f->blf_len,
               buf_flags, &bp, NULL);
     if (error)
         return error;
 
     /*
      * Recover the buffer only if we get an LSN from it and it's less than
      * the lsn of the transaction we are replaying.
      *
      * Note that we have to be extremely careful of readahead here.
      * Readahead does not attach verfiers to the buffers so if we don't
      * actually do any replay after readahead because of the LSN we found
      * in the buffer if more recent than that current transaction then we
      * need to attach the verifier directly. Failure to do so can lead to
      * future recovery actions (e.g. EFI and unlinked list recovery) can
      * operate on the buffers and they won't get the verifier attached. This
      * can lead to blocks on disk having the correct content but a stale
      * CRC.
      *
      * It is safe to assume these clean buffers are currently up to date.
      * If the buffer is dirtied by a later transaction being replayed, then
      * the verifier will be reset to match whatever recover turns that
      * buffer into.
      */
     lsn = xlog_recover_get_buf_lsn(mp, bp, buf_f);
     if (lsn && lsn != -1 && XFS_LSN_CMP(lsn, current_lsn) >= 0) {
         trace_xfs_log_recover_buf_skip(log, buf_f);
         xlog_recover_validate_buf_type(mp, bp, buf_f, NULLCOMMITLSN);
         goto out_release;
     }
 
     if (buf_f->blf_flags & XFS_BLF_INODE_BUF) {
         error = xlog_recover_do_inode_buffer(mp, item, bp, buf_f);
         if (error)
             goto out_release;
     } else if (buf_f->blf_flags &
           (XFS_BLF_UDQUOT_BUF|XFS_BLF_PDQUOT_BUF|XFS_BLF_GDQUOT_BUF)) {
         bool    dirty;
 
         dirty = xlog_recover_do_dquot_buffer(mp, log, item, bp, buf_f);
         if (!dirty)
             goto out_release;
     } else {
         xlog_recover_do_reg_buffer(mp, item, bp, buf_f, current_lsn);
     }
 
     /*
      * Perform delayed write on the buffer.  Asynchronous writes will be
      * slower when taking into account all the buffers to be flushed.
      *
      * Also make sure that only inode buffers with good sizes stay in
      * the buffer cache.  The kernel moves inodes in buffers of 1 block
      * or inode_cluster_size bytes, whichever is bigger.  The inode
      * buffers in the log can be a different size if the log was generated
      * by an older kernel using unclustered inode buffers or a newer kernel
      * running with a different inode cluster size.  Regardless, if
      * the inode buffer size isn't max(blocksize, inode_cluster_size)
      * for *our* value of inode_cluster_size, then we need to keep
      * the buffer out of the buffer cache so that the buffer won't
      * overlap with future reads of those inodes.
      */
     if (XFS_DINODE_MAGIC ==
         be16_to_cpu(*((__be16 *)xfs_buf_offset(bp, 0))) &&
         (BBTOB(bp->b_length) != M_IGEO(log->l_mp)->inode_cluster_size)) {
         xfs_buf_stale(bp);
         error = xfs_bwrite(bp);
     } else {
         ASSERT(bp->b_mount == mp);
         bp->b_flags |= _XBF_LOGRECOVERY;
         xfs_buf_delwri_queue(bp, buffer_list);
     }
 
 out_release:
     xfs_buf_relse(bp);
     return error;
 cancelled:
     trace_xfs_log_recover_buf_cancel(log, buf_f);
     return 0;
 }
 
 const struct xlog_recover_item_ops xlog_buf_item_ops = {
     .item_type      = XFS_LI_BUF,
     .reorder        = xlog_recover_buf_reorder,
     .ra_pass2       = xlog_recover_buf_ra_pass2,
     .commit_pass1       = xlog_recover_buf_commit_pass1,
     .commit_pass2       = xlog_recover_buf_commit_pass2,
 };
 
 #ifdef DEBUG
 void
 xlog_check_buf_cancel_table(
     struct xlog *log)
 {
     int     i;
 
     for (i = 0; i < XLOG_BC_TABLE_SIZE; i++)
         ASSERT(list_empty(&log->l_buf_cancel_table[i]));
 }
 #endif
 
 int
 xlog_alloc_buf_cancel_table(
     struct xlog *log)
 {
     void        *p;
     int     i;
 
     ASSERT(log->l_buf_cancel_table == NULL);
 
     p = kmalloc_array(XLOG_BC_TABLE_SIZE, sizeof(struct list_head),
               GFP_KERNEL);
     if (!p)
         return -ENOMEM;
 
     log->l_buf_cancel_table = p;
     for (i = 0; i < XLOG_BC_TABLE_SIZE; i++)
         INIT_LIST_HEAD(&log->l_buf_cancel_table[i]);
 
     return 0;
 }
 
 void
 xlog_free_buf_cancel_table(
     struct xlog *log)
 {
     int     i;
 
     if (!log->l_buf_cancel_table)
         return;
 
     for (i = 0; i < XLOG_BC_TABLE_SIZE; i++) {
         struct xfs_buf_cancel   *bc;
 
         while ((bc = list_first_entry_or_null(
                 &log->l_buf_cancel_table[i],
                 struct xfs_buf_cancel, bc_list))) {
             list_del(&bc->bc_list);
             kmem_free(bc);
         }
     }
 
     kmem_free(log->l_buf_cancel_table);
     log->l_buf_cancel_table = NULL;
 }

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