OSCL-LXR linux-6.0.1/​fs/​xfs/​xfs_dir2_readdir.c	Source navigation Diff markup Identifier search General search
	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) 2000-2005 Silicon Graphics, Inc.
  * Copyright (c) 2013 Red Hat, 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_mount.h"
 #include "xfs_inode.h"
 #include "xfs_dir2.h"
 #include "xfs_dir2_priv.h"
 #include "xfs_trace.h"
 #include "xfs_bmap.h"
 #include "xfs_trans.h"
 #include "xfs_error.h"
 
 /*
  * Directory file type support functions
  */
 static unsigned char xfs_dir3_filetype_table[] = {
     DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK,
     DT_FIFO, DT_SOCK, DT_LNK, DT_WHT,
 };
 
 unsigned char
 xfs_dir3_get_dtype(
     struct xfs_mount    *mp,
     uint8_t         filetype)
 {
     if (!xfs_has_ftype(mp))
         return DT_UNKNOWN;
 
     if (filetype >= XFS_DIR3_FT_MAX)
         return DT_UNKNOWN;
 
     return xfs_dir3_filetype_table[filetype];
 }
 
 STATIC int
 xfs_dir2_sf_getdents(
     struct xfs_da_args  *args,
     struct dir_context  *ctx)
 {
     int         i;      /* shortform entry number */
     struct xfs_inode    *dp = args->dp; /* incore directory inode */
     struct xfs_mount    *mp = dp->i_mount;
     xfs_dir2_dataptr_t  off;        /* current entry's offset */
     xfs_dir2_sf_entry_t *sfep;      /* shortform directory entry */
     xfs_dir2_sf_hdr_t   *sfp;       /* shortform structure */
     xfs_dir2_dataptr_t  dot_offset;
     xfs_dir2_dataptr_t  dotdot_offset;
     xfs_ino_t       ino;
     struct xfs_da_geometry  *geo = args->geo;
 
     ASSERT(dp->i_df.if_format == XFS_DINODE_FMT_LOCAL);
     ASSERT(dp->i_df.if_bytes == dp->i_disk_size);
     ASSERT(dp->i_df.if_u1.if_data != NULL);
 
     sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;
 
     /*
      * If the block number in the offset is out of range, we're done.
      */
     if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
         return 0;
 
     /*
      * Precalculate offsets for "." and ".." as we will always need them.
      * This relies on the fact that directories always start with the
      * entries for "." and "..".
      */
     dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
             geo->data_entry_offset);
     dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
             geo->data_entry_offset +
             xfs_dir2_data_entsize(mp, sizeof(".") - 1));
 
     /*
      * Put . entry unless we're starting past it.
      */
     if (ctx->pos <= dot_offset) {
         ctx->pos = dot_offset & 0x7fffffff;
         if (!dir_emit(ctx, ".", 1, dp->i_ino, DT_DIR))
             return 0;
     }
 
     /*
      * Put .. entry unless we're starting past it.
      */
     if (ctx->pos <= dotdot_offset) {
         ino = xfs_dir2_sf_get_parent_ino(sfp);
         ctx->pos = dotdot_offset & 0x7fffffff;
         if (!dir_emit(ctx, "..", 2, ino, DT_DIR))
             return 0;
     }
 
     /*
      * Loop while there are more entries and put'ing works.
      */
     sfep = xfs_dir2_sf_firstentry(sfp);
     for (i = 0; i < sfp->count; i++) {
         uint8_t filetype;
 
         off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
                 xfs_dir2_sf_get_offset(sfep));
 
         if (ctx->pos > off) {
             sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep);
             continue;
         }
 
         ino = xfs_dir2_sf_get_ino(mp, sfp, sfep);
         filetype = xfs_dir2_sf_get_ftype(mp, sfep);
         ctx->pos = off & 0x7fffffff;
         if (XFS_IS_CORRUPT(dp->i_mount,
                    !xfs_dir2_namecheck(sfep->name,
                                sfep->namelen)))
             return -EFSCORRUPTED;
         if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
                 xfs_dir3_get_dtype(mp, filetype)))
             return 0;
         sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep);
     }
 
     ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
                                 0x7fffffff;
     return 0;
 }
 
 /*
  * Readdir for block directories.
  */
 STATIC int
 xfs_dir2_block_getdents(
     struct xfs_da_args  *args,
     struct dir_context  *ctx,
     unsigned int        *lock_mode)
 {
     struct xfs_inode    *dp = args->dp; /* incore directory inode */
     struct xfs_buf      *bp;        /* buffer for block */
     int         error;      /* error return value */
     int         wantoff;    /* starting block offset */
     xfs_off_t       cook;
     struct xfs_da_geometry  *geo = args->geo;
     unsigned int        offset, next_offset;
     unsigned int        end;
 
     /*
      * If the block number in the offset is out of range, we're done.
      */
     if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
         return 0;
 
     error = xfs_dir3_block_read(args->trans, dp, &bp);
     if (error)
         return error;
 
     xfs_iunlock(dp, *lock_mode);
     *lock_mode = 0;
 
     /*
      * Extract the byte offset we start at from the seek pointer.
      * We'll skip entries before this.
      */
     wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos);
     xfs_dir3_data_check(dp, bp);
 
     /*
      * Loop over the data portion of the block.
      * Each object is a real entry (dep) or an unused one (dup).
      */
     end = xfs_dir3_data_end_offset(geo, bp->b_addr);
     for (offset = geo->data_entry_offset;
          offset < end;
          offset = next_offset) {
         struct xfs_dir2_data_unused *dup = bp->b_addr + offset;
         struct xfs_dir2_data_entry  *dep = bp->b_addr + offset;
         uint8_t filetype;
 
         /*
          * Unused, skip it.
          */
         if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
             next_offset = offset + be16_to_cpu(dup->length);
             continue;
         }
 
         /*
          * Bump pointer for the next iteration.
          */
         next_offset = offset +
             xfs_dir2_data_entsize(dp->i_mount, dep->namelen);
 
         /*
          * The entry is before the desired starting point, skip it.
          */
         if (offset < wantoff)
             continue;
 
         cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, offset);
 
         ctx->pos = cook & 0x7fffffff;
         filetype = xfs_dir2_data_get_ftype(dp->i_mount, dep);
         /*
          * If it didn't fit, set the final offset to here & return.
          */
         if (XFS_IS_CORRUPT(dp->i_mount,
                    !xfs_dir2_namecheck(dep->name,
                                dep->namelen))) {
             error = -EFSCORRUPTED;
             goto out_rele;
         }
         if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
                 be64_to_cpu(dep->inumber),
                 xfs_dir3_get_dtype(dp->i_mount, filetype)))
             goto out_rele;
     }
 
     /*
      * Reached the end of the block.
      * Set the offset to a non-existent block 1 and return.
      */
     ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
                                 0x7fffffff;
 out_rele:
     xfs_trans_brelse(args->trans, bp);
     return error;
 }
 
 /*
  * Read a directory block and initiate readahead for blocks beyond that.
  * We maintain a sliding readahead window of the remaining space in the
  * buffer rounded up to the nearest block.
  */
 STATIC int
 xfs_dir2_leaf_readbuf(
     struct xfs_da_args  *args,
     size_t          bufsize,
     xfs_dir2_off_t      *cur_off,
     xfs_dablk_t     *ra_blk,
     struct xfs_buf      **bpp)
 {
     struct xfs_inode    *dp = args->dp;
     struct xfs_buf      *bp = NULL;
     struct xfs_da_geometry  *geo = args->geo;
     struct xfs_ifork    *ifp = xfs_ifork_ptr(dp, XFS_DATA_FORK);
     struct xfs_bmbt_irec    map;
     struct blk_plug     plug;
     xfs_dir2_off_t      new_off;
     xfs_dablk_t     next_ra;
     xfs_dablk_t     map_off;
     xfs_dablk_t     last_da;
     struct xfs_iext_cursor  icur;
     int         ra_want;
     int         error = 0;
 
     error = xfs_iread_extents(args->trans, dp, XFS_DATA_FORK);
     if (error)
         goto out;
 
     /*
      * Look for mapped directory blocks at or above the current offset.
      * Truncate down to the nearest directory block to start the scanning
      * operation.
      */
     last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
     map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
     if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
         goto out;
     if (map.br_startoff >= last_da)
         goto out;
     xfs_trim_extent(&map, map_off, last_da - map_off);
 
     /* Read the directory block of that first mapping. */
     new_off = xfs_dir2_da_to_byte(geo, map.br_startoff);
     if (new_off > *cur_off)
         *cur_off = new_off;
     error = xfs_dir3_data_read(args->trans, dp, map.br_startoff, 0, &bp);
     if (error)
         goto out;
 
     /*
      * Start readahead for the next bufsize's worth of dir data blocks.
      * We may have already issued readahead for some of that range;
      * ra_blk tracks the last block we tried to read(ahead).
      */
     ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
     if (*ra_blk >= last_da)
         goto out;
     else if (*ra_blk == 0)
         *ra_blk = map.br_startoff;
     next_ra = map.br_startoff + geo->fsbcount;
     if (next_ra >= last_da)
         goto out_no_ra;
     if (map.br_blockcount < geo->fsbcount &&
         !xfs_iext_next_extent(ifp, &icur, &map))
         goto out_no_ra;
     if (map.br_startoff >= last_da)
         goto out_no_ra;
     xfs_trim_extent(&map, next_ra, last_da - next_ra);
 
     /* Start ra for each dir (not fs) block that has a mapping. */
     blk_start_plug(&plug);
     while (ra_want > 0) {
         next_ra = roundup((xfs_dablk_t)map.br_startoff, geo->fsbcount);
         while (ra_want > 0 &&
                next_ra < map.br_startoff + map.br_blockcount) {
             if (next_ra >= last_da) {
                 *ra_blk = last_da;
                 break;
             }
             if (next_ra > *ra_blk) {
                 xfs_dir3_data_readahead(dp, next_ra,
                             XFS_DABUF_MAP_HOLE_OK);
                 *ra_blk = next_ra;
             }
             ra_want -= geo->fsbcount;
             next_ra += geo->fsbcount;
         }
         if (!xfs_iext_next_extent(ifp, &icur, &map)) {
             *ra_blk = last_da;
             break;
         }
     }
     blk_finish_plug(&plug);
 
 out:
     *bpp = bp;
     return error;
 out_no_ra:
     *ra_blk = last_da;
     goto out;
 }
 
 /*
  * Getdents (readdir) for leaf and node directories.
  * This reads the data blocks only, so is the same for both forms.
  */
 STATIC int
 xfs_dir2_leaf_getdents(
     struct xfs_da_args  *args,
     struct dir_context  *ctx,
     size_t          bufsize,
     unsigned int        *lock_mode)
 {
     struct xfs_inode    *dp = args->dp;
     struct xfs_mount    *mp = dp->i_mount;
     struct xfs_buf      *bp = NULL; /* data block buffer */
     xfs_dir2_data_entry_t   *dep;       /* data entry */
     xfs_dir2_data_unused_t  *dup;       /* unused entry */
     struct xfs_da_geometry  *geo = args->geo;
     xfs_dablk_t     rablk = 0;  /* current readahead block */
     xfs_dir2_off_t      curoff;     /* current overall offset */
     int         length;     /* temporary length value */
     int         byteoff;    /* offset in current block */
     unsigned int        offset = 0;
     int         error = 0;  /* error return value */
 
     /*
      * If the offset is at or past the largest allowed value,
      * give up right away.
      */
     if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
         return 0;
 
     /*
      * Inside the loop we keep the main offset value as a byte offset
      * in the directory file.
      */
     curoff = xfs_dir2_dataptr_to_byte(ctx->pos);
 
     /*
      * Loop over directory entries until we reach the end offset.
      * Get more blocks and readahead as necessary.
      */
     while (curoff < XFS_DIR2_LEAF_OFFSET) {
         uint8_t filetype;
 
         /*
          * If we have no buffer, or we're off the end of the
          * current buffer, need to get another one.
          */
         if (!bp || offset >= geo->blksize) {
             if (bp) {
                 xfs_trans_brelse(args->trans, bp);
                 bp = NULL;
             }
 
             if (*lock_mode == 0)
                 *lock_mode = xfs_ilock_data_map_shared(dp);
             error = xfs_dir2_leaf_readbuf(args, bufsize, &curoff,
                     &rablk, &bp);
             if (error || !bp)
                 break;
 
             xfs_iunlock(dp, *lock_mode);
             *lock_mode = 0;
 
             xfs_dir3_data_check(dp, bp);
             /*
              * Find our position in the block.
              */
             offset = geo->data_entry_offset;
             byteoff = xfs_dir2_byte_to_off(geo, curoff);
             /*
              * Skip past the header.
              */
             if (byteoff == 0)
                 curoff += geo->data_entry_offset;
             /*
              * Skip past entries until we reach our offset.
              */
             else {
                 while (offset < byteoff) {
                     dup = bp->b_addr + offset;
 
                     if (be16_to_cpu(dup->freetag)
                           == XFS_DIR2_DATA_FREE_TAG) {
 
                         length = be16_to_cpu(dup->length);
                         offset += length;
                         continue;
                     }
                     dep = bp->b_addr + offset;
                     length = xfs_dir2_data_entsize(mp,
                             dep->namelen);
                     offset += length;
                 }
                 /*
                  * Now set our real offset.
                  */
                 curoff =
                     xfs_dir2_db_off_to_byte(geo,
                         xfs_dir2_byte_to_db(geo, curoff),
                         offset);
                 if (offset >= geo->blksize)
                     continue;
             }
         }
 
         /*
          * We have a pointer to an entry.  Is it a live one?
          */
         dup = bp->b_addr + offset;
 
         /*
          * No, it's unused, skip over it.
          */
         if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
             length = be16_to_cpu(dup->length);
             offset += length;
             curoff += length;
             continue;
         }
 
         dep = bp->b_addr + offset;
         length = xfs_dir2_data_entsize(mp, dep->namelen);
         filetype = xfs_dir2_data_get_ftype(mp, dep);
 
         ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
         if (XFS_IS_CORRUPT(dp->i_mount,
                    !xfs_dir2_namecheck(dep->name,
                                dep->namelen))) {
             error = -EFSCORRUPTED;
             break;
         }
         if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
                 be64_to_cpu(dep->inumber),
                 xfs_dir3_get_dtype(dp->i_mount, filetype)))
             break;
 
         /*
          * Advance to next entry in the block.
          */
         offset += length;
         curoff += length;
         /* bufsize may have just been a guess; don't go negative */
         bufsize = bufsize > length ? bufsize - length : 0;
     }
 
     /*
      * All done.  Set output offset value to current offset.
      */
     if (curoff > xfs_dir2_dataptr_to_byte(XFS_DIR2_MAX_DATAPTR))
         ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
     else
         ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
     if (bp)
         xfs_trans_brelse(args->trans, bp);
     return error;
 }
 
 /*
  * Read a directory.
  *
  * If supplied, the transaction collects locked dir buffers to avoid
  * nested buffer deadlocks.  This function does not dirty the
  * transaction.  The caller must hold the IOLOCK (shared or exclusive)
  * before calling this function.
  */
 int
 xfs_readdir(
     struct xfs_trans    *tp,
     struct xfs_inode    *dp,
     struct dir_context  *ctx,
     size_t          bufsize)
 {
     struct xfs_da_args  args = { NULL };
     unsigned int        lock_mode;
     int         isblock;
     int         error;
 
     trace_xfs_readdir(dp);
 
     if (xfs_is_shutdown(dp->i_mount))
         return -EIO;
 
     ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
     ASSERT(xfs_isilocked(dp, XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
     XFS_STATS_INC(dp->i_mount, xs_dir_getdents);
 
     args.dp = dp;
     args.geo = dp->i_mount->m_dir_geo;
     args.trans = tp;
 
     if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL)
         return xfs_dir2_sf_getdents(&args, ctx);
 
     lock_mode = xfs_ilock_data_map_shared(dp);
     error = xfs_dir2_isblock(&args, &isblock);
     if (error)
         goto out_unlock;
 
     if (isblock) {
         error = xfs_dir2_block_getdents(&args, ctx, &lock_mode);
         goto out_unlock;
     }
 
     error = xfs_dir2_leaf_getdents(&args, ctx, bufsize, &lock_mode);
 
 out_unlock:
     if (lock_mode)
         xfs_iunlock(dp, lock_mode);
     return error;
 }

This page was automatically generated by the 2.1.0 LXR engine. The LXR team