Line data    Source code

       1             : // SPDX-License-Identifier: GPL-2.0
       2             : /*
       3             :  * Copyright (C) 2010 Red Hat, Inc.
       4             :  * Copyright (c) 2016-2021 Christoph Hellwig.
       5             :  */
       6             : #include <linux/fs.h>
       7             : #include <linux/iomap.h>
       8             : #include "trace.h"
       9             : 
      10             : /*
      11             :  * Advance to the next range we need to map.
      12             :  *
      13             :  * If the iomap is marked IOMAP_F_STALE, it means the existing map was not fully
      14             :  * processed - it was aborted because the extent the iomap spanned may have been
      15             :  * changed during the operation. In this case, the iteration behaviour is to
      16             :  * remap the unprocessed range of the iter, and that means we may need to remap
      17             :  * even when we've made no progress (i.e. iter->processed = 0). Hence the
      18             :  * "finished iterating" case needs to distinguish between
      19             :  * (processed = 0) meaning we are done and (processed = 0 && stale) meaning we
      20             :  * need to remap the entire remaining range.
      21             :  */
      22   924810260 : static inline int iomap_iter_advance(struct iomap_iter *iter)
      23             : {
      24   924810260 :         bool stale = iter->iomap.flags & IOMAP_F_STALE;
      25             : 
      26             :         /* handle the previous iteration (if any) */
      27   924810260 :         if (iter->iomap.length) {
      28   510375373 :                 if (iter->processed < 0)
      29        1368 :                         return iter->processed;
      30   510374005 :                 if (!iter->processed && !stale)
      31             :                         return 0;
      32   510186925 :                 if (WARN_ON_ONCE(iter->processed > iomap_length(iter)))
      33             :                         return -EIO;
      34   510186925 :                 iter->pos += iter->processed;
      35   510186925 :                 iter->len -= iter->processed;
      36   510186925 :                 if (!iter->len)
      37             :                         return 0;
      38             :         }
      39             : 
      40             :         /* clear the state for the next iteration */
      41   511960076 :         iter->processed = 0;
      42   511960076 :         memset(&iter->iomap, 0, sizeof(iter->iomap));
      43   511960076 :         memset(&iter->srcmap, 0, sizeof(iter->srcmap));
      44   511960076 :         return 1;
      45             : }
      46             : 
      47   510380359 : static inline void iomap_iter_done(struct iomap_iter *iter)
      48             : {
      49   510380359 :         WARN_ON_ONCE(iter->iomap.offset > iter->pos);
      50   510380359 :         WARN_ON_ONCE(iter->iomap.length == 0);
      51   510380359 :         WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos);
      52   510380359 :         WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_STALE);
      53             : 
      54   510380359 :         trace_iomap_iter_dstmap(iter->inode, &iter->iomap);
      55   510379149 :         if (iter->srcmap.type != IOMAP_HOLE)
      56     2988108 :                 trace_iomap_iter_srcmap(iter->inode, &iter->srcmap);
      57   510379125 : }
      58             : 
      59             : /**
      60             :  * iomap_iter - iterate over a ranges in a file
      61             :  * @iter: iteration structue
      62             :  * @ops: iomap ops provided by the file system
      63             :  *
      64             :  * Iterate over filesystem-provided space mappings for the provided file range.
      65             :  *
      66             :  * This function handles cleanup of resources acquired for iteration when the
      67             :  * filesystem indicates there are no more space mappings, which means that this
      68             :  * function must be called in a loop that continues as long it returns a
      69             :  * positive value.  If 0 or a negative value is returned, the caller must not
      70             :  * return to the loop body.  Within a loop body, there are two ways to break out
      71             :  * of the loop body:  leave @iter.processed unchanged, or set it to a negative
      72             :  * errno.
      73             :  */
      74   924829966 : int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
      75             : {
      76   924829966 :         int ret;
      77             : 
      78   924829966 :         if (iter->iomap.length && ops->iomap_end) {
      79   117177728 :                 ret = ops->iomap_end(iter->inode, iter->pos, iomap_length(iter),
      80   117177728 :                                 iter->processed > 0 ? iter->processed : 0,
      81             :                                 iter->flags, &iter->iomap);
      82   117169102 :                 if (ret < 0 && !iter->processed)
      83             :                         return ret;
      84             :         }
      85             : 
      86   924821340 :         trace_iomap_iter(iter, ops, _RET_IP_);
      87   924530382 :         ret = iomap_iter_advance(iter);
      88   924840395 :         if (ret <= 0)
      89             :                 return ret;
      90             : 
      91   511990833 :         ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,
      92             :                                &iter->iomap, &iter->srcmap);
      93   512077542 :         if (ret < 0)
      94             :                 return ret;
      95   510364049 :         iomap_iter_done(iter);
      96   510364049 :         return 1;
      97             : }