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![Darrick J. Wong](/assets/img/avatar_default.png)
Currently, the dir2 leaf block getdents function uses a complex state tracking mechanism to create a shadow copy of the block mappings and then uses the shadow copy to schedule readahead. Since the read and readahead functions are perfectly capable of reading the mappings themselves, we can tear all that out in favor of a simpler function that simply keeps pushing the readahead window further out. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
536 lines
14 KiB
C
536 lines
14 KiB
C
/*
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* Copyright (c) 2000-2005 Silicon Graphics, Inc.
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* Copyright (c) 2013 Red Hat, Inc.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "xfs.h"
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#include "xfs_fs.h"
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#include "xfs_format.h"
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#include "xfs_log_format.h"
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#include "xfs_trans_resv.h"
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#include "xfs_bit.h"
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#include "xfs_mount.h"
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#include "xfs_da_format.h"
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#include "xfs_da_btree.h"
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#include "xfs_inode.h"
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#include "xfs_dir2.h"
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#include "xfs_dir2_priv.h"
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#include "xfs_error.h"
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#include "xfs_trace.h"
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#include "xfs_bmap.h"
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#include "xfs_trans.h"
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/*
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* Directory file type support functions
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*/
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static unsigned char xfs_dir3_filetype_table[] = {
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DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK,
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DT_FIFO, DT_SOCK, DT_LNK, DT_WHT,
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};
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static unsigned char
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xfs_dir3_get_dtype(
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struct xfs_mount *mp,
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__uint8_t filetype)
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{
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if (!xfs_sb_version_hasftype(&mp->m_sb))
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return DT_UNKNOWN;
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if (filetype >= XFS_DIR3_FT_MAX)
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return DT_UNKNOWN;
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return xfs_dir3_filetype_table[filetype];
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}
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STATIC int
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xfs_dir2_sf_getdents(
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struct xfs_da_args *args,
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struct dir_context *ctx)
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{
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int i; /* shortform entry number */
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struct xfs_inode *dp = args->dp; /* incore directory inode */
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xfs_dir2_dataptr_t off; /* current entry's offset */
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xfs_dir2_sf_entry_t *sfep; /* shortform directory entry */
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xfs_dir2_sf_hdr_t *sfp; /* shortform structure */
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xfs_dir2_dataptr_t dot_offset;
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xfs_dir2_dataptr_t dotdot_offset;
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xfs_ino_t ino;
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struct xfs_da_geometry *geo = args->geo;
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ASSERT(dp->i_df.if_flags & XFS_IFINLINE);
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ASSERT(dp->i_df.if_bytes == dp->i_d.di_size);
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ASSERT(dp->i_df.if_u1.if_data != NULL);
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sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;
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/*
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* If the block number in the offset is out of range, we're done.
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*/
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if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
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return 0;
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/*
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* Precalculate offsets for . and .. as we will always need them.
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*
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* XXX(hch): the second argument is sometimes 0 and sometimes
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* geo->datablk
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*/
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dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
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dp->d_ops->data_dot_offset);
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dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
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dp->d_ops->data_dotdot_offset);
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/*
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* Put . entry unless we're starting past it.
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*/
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if (ctx->pos <= dot_offset) {
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ctx->pos = dot_offset & 0x7fffffff;
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if (!dir_emit(ctx, ".", 1, dp->i_ino, DT_DIR))
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return 0;
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}
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/*
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* Put .. entry unless we're starting past it.
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*/
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if (ctx->pos <= dotdot_offset) {
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ino = dp->d_ops->sf_get_parent_ino(sfp);
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ctx->pos = dotdot_offset & 0x7fffffff;
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if (!dir_emit(ctx, "..", 2, ino, DT_DIR))
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return 0;
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}
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/*
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* Loop while there are more entries and put'ing works.
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*/
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sfep = xfs_dir2_sf_firstentry(sfp);
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for (i = 0; i < sfp->count; i++) {
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__uint8_t filetype;
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off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
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xfs_dir2_sf_get_offset(sfep));
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if (ctx->pos > off) {
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sfep = dp->d_ops->sf_nextentry(sfp, sfep);
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continue;
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}
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ino = dp->d_ops->sf_get_ino(sfp, sfep);
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filetype = dp->d_ops->sf_get_ftype(sfep);
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ctx->pos = off & 0x7fffffff;
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if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
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xfs_dir3_get_dtype(dp->i_mount, filetype)))
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return 0;
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sfep = dp->d_ops->sf_nextentry(sfp, sfep);
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}
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ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
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0x7fffffff;
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return 0;
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}
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/*
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* Readdir for block directories.
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*/
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STATIC int
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xfs_dir2_block_getdents(
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struct xfs_da_args *args,
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struct dir_context *ctx)
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{
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struct xfs_inode *dp = args->dp; /* incore directory inode */
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xfs_dir2_data_hdr_t *hdr; /* block header */
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struct xfs_buf *bp; /* buffer for block */
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xfs_dir2_block_tail_t *btp; /* block tail */
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xfs_dir2_data_entry_t *dep; /* block data entry */
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xfs_dir2_data_unused_t *dup; /* block unused entry */
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char *endptr; /* end of the data entries */
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int error; /* error return value */
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char *ptr; /* current data entry */
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int wantoff; /* starting block offset */
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xfs_off_t cook;
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struct xfs_da_geometry *geo = args->geo;
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int lock_mode;
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/*
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* If the block number in the offset is out of range, we're done.
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*/
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if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
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return 0;
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lock_mode = xfs_ilock_data_map_shared(dp);
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error = xfs_dir3_block_read(NULL, dp, &bp);
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xfs_iunlock(dp, lock_mode);
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if (error)
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return error;
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/*
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* Extract the byte offset we start at from the seek pointer.
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* We'll skip entries before this.
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*/
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wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos);
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hdr = bp->b_addr;
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xfs_dir3_data_check(dp, bp);
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/*
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* Set up values for the loop.
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*/
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btp = xfs_dir2_block_tail_p(geo, hdr);
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ptr = (char *)dp->d_ops->data_entry_p(hdr);
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endptr = (char *)xfs_dir2_block_leaf_p(btp);
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/*
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* Loop over the data portion of the block.
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* Each object is a real entry (dep) or an unused one (dup).
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*/
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while (ptr < endptr) {
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__uint8_t filetype;
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dup = (xfs_dir2_data_unused_t *)ptr;
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/*
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* Unused, skip it.
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*/
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if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
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ptr += be16_to_cpu(dup->length);
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continue;
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}
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dep = (xfs_dir2_data_entry_t *)ptr;
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/*
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* Bump pointer for the next iteration.
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*/
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ptr += dp->d_ops->data_entsize(dep->namelen);
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/*
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* The entry is before the desired starting point, skip it.
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*/
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if ((char *)dep - (char *)hdr < wantoff)
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continue;
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cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
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(char *)dep - (char *)hdr);
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ctx->pos = cook & 0x7fffffff;
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filetype = dp->d_ops->data_get_ftype(dep);
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/*
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* If it didn't fit, set the final offset to here & return.
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*/
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if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
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be64_to_cpu(dep->inumber),
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xfs_dir3_get_dtype(dp->i_mount, filetype))) {
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xfs_trans_brelse(NULL, bp);
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return 0;
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}
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}
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/*
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* Reached the end of the block.
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* Set the offset to a non-existent block 1 and return.
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*/
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ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
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0x7fffffff;
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xfs_trans_brelse(NULL, bp);
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return 0;
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}
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/*
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* Read a directory block and initiate readahead for blocks beyond that.
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* We maintain a sliding readahead window of the remaining space in the
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* buffer rounded up to the nearest block.
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*/
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STATIC int
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xfs_dir2_leaf_readbuf(
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struct xfs_da_args *args,
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size_t bufsize,
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xfs_dir2_off_t *cur_off,
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xfs_dablk_t *ra_blk,
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struct xfs_buf **bpp)
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{
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struct xfs_inode *dp = args->dp;
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struct xfs_buf *bp = NULL;
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struct xfs_da_geometry *geo = args->geo;
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struct xfs_ifork *ifp = XFS_IFORK_PTR(dp, XFS_DATA_FORK);
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struct xfs_bmbt_irec map;
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struct blk_plug plug;
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xfs_dir2_off_t new_off;
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xfs_dablk_t next_ra;
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xfs_dablk_t map_off;
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xfs_dablk_t last_da;
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xfs_extnum_t idx;
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int ra_want;
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int error = 0;
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if (!(ifp->if_flags & XFS_IFEXTENTS)) {
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error = xfs_iread_extents(args->trans, dp, XFS_DATA_FORK);
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if (error)
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goto out;
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}
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/*
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* Look for mapped directory blocks at or above the current offset.
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* Truncate down to the nearest directory block to start the scanning
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* operation.
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*/
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last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
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map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
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if (!xfs_iext_lookup_extent(dp, ifp, map_off, &idx, &map))
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goto out;
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if (map.br_startoff >= last_da)
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goto out;
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xfs_trim_extent(&map, map_off, last_da - map_off);
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/* Read the directory block of that first mapping. */
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new_off = xfs_dir2_da_to_byte(geo, map.br_startoff);
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if (new_off > *cur_off)
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*cur_off = new_off;
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error = xfs_dir3_data_read(args->trans, dp, map.br_startoff, -1, &bp);
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if (error)
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goto out;
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/*
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* Start readahead for the next bufsize's worth of dir data blocks.
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* We may have already issued readahead for some of that range;
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* ra_blk tracks the last block we tried to read(ahead).
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*/
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ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
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if (*ra_blk >= last_da)
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goto out;
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else if (*ra_blk == 0)
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*ra_blk = map.br_startoff;
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next_ra = map.br_startoff + geo->fsbcount;
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if (next_ra >= last_da)
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goto out_no_ra;
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if (map.br_blockcount < geo->fsbcount &&
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!xfs_iext_get_extent(ifp, ++idx, &map))
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goto out_no_ra;
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if (map.br_startoff >= last_da)
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goto out_no_ra;
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xfs_trim_extent(&map, next_ra, last_da - next_ra);
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/* Start ra for each dir (not fs) block that has a mapping. */
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blk_start_plug(&plug);
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while (ra_want > 0) {
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next_ra = roundup((xfs_dablk_t)map.br_startoff, geo->fsbcount);
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while (ra_want > 0 &&
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next_ra < map.br_startoff + map.br_blockcount) {
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if (next_ra >= last_da) {
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*ra_blk = last_da;
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break;
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}
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if (next_ra > *ra_blk) {
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xfs_dir3_data_readahead(dp, next_ra, -2);
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*ra_blk = next_ra;
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}
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ra_want -= geo->fsbcount;
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next_ra += geo->fsbcount;
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}
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if (!xfs_iext_get_extent(ifp, ++idx, &map)) {
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*ra_blk = last_da;
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break;
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}
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}
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blk_finish_plug(&plug);
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out:
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*bpp = bp;
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return error;
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out_no_ra:
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*ra_blk = last_da;
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goto out;
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}
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/*
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* Getdents (readdir) for leaf and node directories.
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* This reads the data blocks only, so is the same for both forms.
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*/
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STATIC int
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xfs_dir2_leaf_getdents(
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struct xfs_da_args *args,
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struct dir_context *ctx,
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size_t bufsize)
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{
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struct xfs_inode *dp = args->dp;
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struct xfs_buf *bp = NULL; /* data block buffer */
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xfs_dir2_data_hdr_t *hdr; /* data block header */
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xfs_dir2_data_entry_t *dep; /* data entry */
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xfs_dir2_data_unused_t *dup; /* unused entry */
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char *ptr = NULL; /* pointer to current data */
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struct xfs_da_geometry *geo = args->geo;
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xfs_dablk_t rablk = 0; /* current readahead block */
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xfs_dir2_off_t curoff; /* current overall offset */
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int length; /* temporary length value */
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int byteoff; /* offset in current block */
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int lock_mode;
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int error = 0; /* error return value */
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/*
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* If the offset is at or past the largest allowed value,
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* give up right away.
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*/
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if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
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return 0;
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/*
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* Inside the loop we keep the main offset value as a byte offset
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* in the directory file.
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*/
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curoff = xfs_dir2_dataptr_to_byte(ctx->pos);
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/*
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* Loop over directory entries until we reach the end offset.
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* Get more blocks and readahead as necessary.
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*/
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while (curoff < XFS_DIR2_LEAF_OFFSET) {
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__uint8_t filetype;
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/*
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* If we have no buffer, or we're off the end of the
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* current buffer, need to get another one.
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*/
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if (!bp || ptr >= (char *)bp->b_addr + geo->blksize) {
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if (bp) {
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xfs_trans_brelse(args->trans, bp);
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bp = NULL;
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}
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lock_mode = xfs_ilock_data_map_shared(dp);
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error = xfs_dir2_leaf_readbuf(args, bufsize, &curoff,
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&rablk, &bp);
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xfs_iunlock(dp, lock_mode);
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if (error || !bp)
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break;
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hdr = bp->b_addr;
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xfs_dir3_data_check(dp, bp);
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/*
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* Find our position in the block.
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*/
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ptr = (char *)dp->d_ops->data_entry_p(hdr);
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byteoff = xfs_dir2_byte_to_off(geo, curoff);
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/*
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* Skip past the header.
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*/
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if (byteoff == 0)
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curoff += dp->d_ops->data_entry_offset;
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/*
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* Skip past entries until we reach our offset.
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*/
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else {
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while ((char *)ptr - (char *)hdr < byteoff) {
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dup = (xfs_dir2_data_unused_t *)ptr;
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if (be16_to_cpu(dup->freetag)
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== XFS_DIR2_DATA_FREE_TAG) {
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length = be16_to_cpu(dup->length);
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ptr += length;
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continue;
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}
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dep = (xfs_dir2_data_entry_t *)ptr;
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length =
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dp->d_ops->data_entsize(dep->namelen);
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ptr += length;
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}
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/*
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* Now set our real offset.
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*/
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curoff =
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xfs_dir2_db_off_to_byte(geo,
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xfs_dir2_byte_to_db(geo, curoff),
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(char *)ptr - (char *)hdr);
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if (ptr >= (char *)hdr + geo->blksize) {
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continue;
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}
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}
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}
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/*
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* We have a pointer to an entry.
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* Is it a live one?
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*/
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dup = (xfs_dir2_data_unused_t *)ptr;
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/*
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* No, it's unused, skip over it.
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*/
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if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
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length = be16_to_cpu(dup->length);
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ptr += length;
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curoff += length;
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continue;
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}
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dep = (xfs_dir2_data_entry_t *)ptr;
|
|
length = dp->d_ops->data_entsize(dep->namelen);
|
|
filetype = dp->d_ops->data_get_ftype(dep);
|
|
|
|
ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
|
|
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.
|
|
*/
|
|
ptr += 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(NULL, bp);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Read a directory.
|
|
*/
|
|
int
|
|
xfs_readdir(
|
|
struct xfs_inode *dp,
|
|
struct dir_context *ctx,
|
|
size_t bufsize)
|
|
{
|
|
struct xfs_da_args args = { NULL };
|
|
int rval;
|
|
int v;
|
|
|
|
trace_xfs_readdir(dp);
|
|
|
|
if (XFS_FORCED_SHUTDOWN(dp->i_mount))
|
|
return -EIO;
|
|
|
|
ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
|
|
XFS_STATS_INC(dp->i_mount, xs_dir_getdents);
|
|
|
|
args.dp = dp;
|
|
args.geo = dp->i_mount->m_dir_geo;
|
|
|
|
if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
|
|
rval = xfs_dir2_sf_getdents(&args, ctx);
|
|
else if ((rval = xfs_dir2_isblock(&args, &v)))
|
|
;
|
|
else if (v)
|
|
rval = xfs_dir2_block_getdents(&args, ctx);
|
|
else
|
|
rval = xfs_dir2_leaf_getdents(&args, ctx, bufsize);
|
|
|
|
return rval;
|
|
}
|