fs/iomap/seek.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2017 Red Hat, Inc.
   4  * Copyright (c) 2018 Christoph Hellwig.
   5  */
   6 #include <linux/module.h>
   7 #include <linux/compiler.h>
   8 #include <linux/fs.h>
   9 #include <linux/iomap.h>
  10 #include <linux/pagemap.h>
  11 #include <linux/pagevec.h>
  12
  13 static loff_t
  14 iomap_seek_hole_actor(struct inode *inode, loff_t start, loff_t length,
  15                       void *data, struct iomap *iomap, struct iomap *srcmap)
  16 {
  17         loff_t offset = start;
  18
  19         switch (iomap->type) {
  20         case IOMAP_UNWRITTEN:
  21                 offset = mapping_seek_hole_data(inode->i_mapping, start,
  22                                 start + length, SEEK_HOLE);
  23                 if (offset == start + length)
  24                         return length;
  25                 fallthrough;
  26         case IOMAP_HOLE:
  27                 *(loff_t *)data = offset;
  28                 return 0;
  29         default:
  30                 return length;
  31         }
  32 }
  33
  34 loff_t
  35 iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
  36 {
  37         loff_t size = i_size_read(inode);
  38         loff_t length = size - offset;
  39         loff_t ret;
  40
  41         /* Nothing to be found before or beyond the end of the file. */
  42         if (offset < 0 || offset >= size)
  43                 return -ENXIO;
  44
  45         while (length > 0) {
  46                 ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
  47                                   &offset, iomap_seek_hole_actor);
  48                 if (ret < 0)
  49                         return ret;
  50                 if (ret == 0)
  51                         break;
  52
  53                 offset += ret;
  54                 length -= ret;
  55         }
  56
  57         return offset;
  58 }
  59 EXPORT_SYMBOL_GPL(iomap_seek_hole);
  60
  61 static loff_t
  62 iomap_seek_data_actor(struct inode *inode, loff_t start, loff_t length,
  63                       void *data, struct iomap *iomap, struct iomap *srcmap)
  64 {
  65         loff_t offset = start;
  66
  67         switch (iomap->type) {
  68         case IOMAP_HOLE:
  69                 return length;
  70         case IOMAP_UNWRITTEN:
  71                 offset = mapping_seek_hole_data(inode->i_mapping, start,
  72                                 start + length, SEEK_DATA);
  73                 if (offset < 0)
  74                         return length;
  75                 fallthrough;
  76         default:
  77                 *(loff_t *)data = offset;
  78                 return 0;
  79         }
  80 }
  81
  82 loff_t
  83 iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
  84 {
  85         loff_t size = i_size_read(inode);
  86         loff_t length = size - offset;
  87         loff_t ret;
  88
  89         /* Nothing to be found before or beyond the end of the file. */
  90         if (offset < 0 || offset >= size)
  91                 return -ENXIO;
  92
  93         while (length > 0) {
  94                 ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
  95                                   &offset, iomap_seek_data_actor);
  96                 if (ret < 0)
  97                         return ret;
  98                 if (ret == 0)
  99                         break;
 100
 101                 offset += ret;
 102                 length -= ret;
 103         }
 104
 105         if (length <= 0)
 106                 return -ENXIO;
 107         return offset;
 108 }
 109 EXPORT_SYMBOL_GPL(iomap_seek_data);