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/iomap.h> 7 #include "trace.h" 8 9 static inline void iomap_iter_reset_iomap(struct iomap_iter *iter) 10 { 11 iter->status = 0; 12 memset(&iter->iomap, 0, sizeof(iter->iomap)); 13 memset(&iter->srcmap, 0, sizeof(iter->srcmap)); 14 } 15 16 /* 17 * Advance the current iterator position and output the length remaining for the 18 * current mapping. 19 */ 20 int iomap_iter_advance(struct iomap_iter *iter, u64 *count) 21 { 22 if (WARN_ON_ONCE(*count > iomap_length(iter))) 23 return -EIO; 24 iter->pos += *count; 25 iter->len -= *count; 26 *count = iomap_length(iter); 27 return 0; 28 } 29 30 static inline void iomap_iter_done(struct iomap_iter *iter) 31 { 32 WARN_ON_ONCE(iter->iomap.offset > iter->pos); 33 WARN_ON_ONCE(iter->iomap.length == 0); 34 WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos); 35 WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_STALE); 36 37 iter->iter_start_pos = iter->pos; 38 39 trace_iomap_iter_dstmap(iter->inode, &iter->iomap); 40 if (iter->srcmap.type != IOMAP_HOLE) 41 trace_iomap_iter_srcmap(iter->inode, &iter->srcmap); 42 } 43 44 /** 45 * iomap_iter - iterate over a ranges in a file 46 * @iter: iteration structue 47 * @ops: iomap ops provided by the file system 48 * 49 * Iterate over filesystem-provided space mappings for the provided file range. 50 * 51 * This function handles cleanup of resources acquired for iteration when the 52 * filesystem indicates there are no more space mappings, which means that this 53 * function must be called in a loop that continues as long it returns a 54 * positive value. If 0 or a negative value is returned, the caller must not 55 * return to the loop body. Within a loop body, there are two ways to break out 56 * of the loop body: leave @iter.status unchanged, or set it to a negative 57 * errno. 58 */ 59 int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops) 60 { 61 bool stale = iter->iomap.flags & IOMAP_F_STALE; 62 ssize_t advanced; 63 u64 olen; 64 int ret; 65 66 trace_iomap_iter(iter, ops, _RET_IP_); 67 68 if (!iter->iomap.length) 69 goto begin; 70 71 /* 72 * Calculate how far the iter was advanced and the original length bytes 73 * for ->iomap_end(). 74 */ 75 advanced = iter->pos - iter->iter_start_pos; 76 olen = iter->len + advanced; 77 78 if (ops->iomap_end) { 79 ret = ops->iomap_end(iter->inode, iter->iter_start_pos, 80 iomap_length_trim(iter, iter->iter_start_pos, 81 olen), 82 advanced, iter->flags, &iter->iomap); 83 if (ret < 0 && !advanced) 84 return ret; 85 } 86 87 /* detect old return semantics where this would advance */ 88 if (WARN_ON_ONCE(iter->status > 0)) 89 iter->status = -EIO; 90 91 /* 92 * Use iter->len to determine whether to continue onto the next mapping. 93 * Explicitly terminate on error status or if the current iter has not 94 * advanced at all (i.e. no work was done for some reason) unless the 95 * mapping has been marked stale and needs to be reprocessed. 96 */ 97 if (iter->status < 0) 98 ret = iter->status; 99 else if (iter->len == 0 || (!advanced && !stale)) 100 ret = 0; 101 else 102 ret = 1; 103 iomap_iter_reset_iomap(iter); 104 if (ret <= 0) 105 return ret; 106 107 begin: 108 ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags, 109 &iter->iomap, &iter->srcmap); 110 if (ret < 0) 111 return ret; 112 iomap_iter_done(iter); 113 return 1; 114 } 115