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 static inline int iomap_iter_advance(struct iomap_iter *iter) 23 { 24 bool stale = iter->iomap.flags & IOMAP_F_STALE; 25 int ret = 1; 26 27 /* handle the previous iteration (if any) */ 28 if (iter->iomap.length) { 29 if (iter->processed < 0) 30 return iter->processed; 31 if (WARN_ON_ONCE(iter->processed > iomap_length(iter))) 32 return -EIO; 33 iter->pos += iter->processed; 34 iter->len -= iter->processed; 35 if (!iter->len || (!iter->processed && !stale)) 36 ret = 0; 37 } 38 39 /* clear the per iteration state */ 40 iter->processed = 0; 41 memset(&iter->iomap, 0, sizeof(iter->iomap)); 42 memset(&iter->srcmap, 0, sizeof(iter->srcmap)); 43 return ret; 44 } 45 46 static inline void iomap_iter_done(struct iomap_iter *iter) 47 { 48 WARN_ON_ONCE(iter->iomap.offset > iter->pos); 49 WARN_ON_ONCE(iter->iomap.length == 0); 50 WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos); 51 WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_STALE); 52 53 trace_iomap_iter_dstmap(iter->inode, &iter->iomap); 54 if (iter->srcmap.type != IOMAP_HOLE) 55 trace_iomap_iter_srcmap(iter->inode, &iter->srcmap); 56 } 57 58 /** 59 * iomap_iter - iterate over a ranges in a file 60 * @iter: iteration structue 61 * @ops: iomap ops provided by the file system 62 * 63 * Iterate over filesystem-provided space mappings for the provided file range. 64 * 65 * This function handles cleanup of resources acquired for iteration when the 66 * filesystem indicates there are no more space mappings, which means that this 67 * function must be called in a loop that continues as long it returns a 68 * positive value. If 0 or a negative value is returned, the caller must not 69 * return to the loop body. Within a loop body, there are two ways to break out 70 * of the loop body: leave @iter.processed unchanged, or set it to a negative 71 * errno. 72 */ 73 int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops) 74 { 75 int ret; 76 77 if (iter->iomap.length && ops->iomap_end) { 78 ret = ops->iomap_end(iter->inode, iter->pos, iomap_length(iter), 79 iter->processed > 0 ? iter->processed : 0, 80 iter->flags, &iter->iomap); 81 if (ret < 0 && !iter->processed) 82 return ret; 83 } 84 85 trace_iomap_iter(iter, ops, _RET_IP_); 86 ret = iomap_iter_advance(iter); 87 if (ret <= 0) 88 return ret; 89 90 ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags, 91 &iter->iomap, &iter->srcmap); 92 if (ret < 0) 93 return ret; 94 iomap_iter_done(iter); 95 return 1; 96 } 97