fs/iomap/iter.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright (C) 2010 Red Hat, Inc.
0004  * Copyright (c) 2016-2021 Christoph Hellwig.
0005  */
0006 #include <linux/fs.h>
0007 #include <linux/iomap.h>
0008 #include "trace.h"
0009
0010 static inline int iomap_iter_advance(struct iomap_iter *iter)
0011 {
0012     /* handle the previous iteration (if any) */
0013     if (iter->iomap.length) {
0014         if (iter->processed <= 0)
0015             return iter->processed;
0016         if (WARN_ON_ONCE(iter->processed > iomap_length(iter)))
0017             return -EIO;
0018         iter->pos += iter->processed;
0019         iter->len -= iter->processed;
0020         if (!iter->len)
0021             return 0;
0022     }
0023
0024     /* clear the state for the next iteration */
0025     iter->processed = 0;
0026     memset(&iter->iomap, 0, sizeof(iter->iomap));
0027     memset(&iter->srcmap, 0, sizeof(iter->srcmap));
0028     return 1;
0029 }
0030
0031 static inline void iomap_iter_done(struct iomap_iter *iter)
0032 {
0033     WARN_ON_ONCE(iter->iomap.offset > iter->pos);
0034     WARN_ON_ONCE(iter->iomap.length == 0);
0035     WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos);
0036
0037     trace_iomap_iter_dstmap(iter->inode, &iter->iomap);
0038     if (iter->srcmap.type != IOMAP_HOLE)
0039         trace_iomap_iter_srcmap(iter->inode, &iter->srcmap);
0040 }
0041
0042 /**
0043  * iomap_iter - iterate over a ranges in a file
0044  * @iter: iteration structue
0045  * @ops: iomap ops provided by the file system
0046  *
0047  * Iterate over filesystem-provided space mappings for the provided file range.
0048  *
0049  * This function handles cleanup of resources acquired for iteration when the
0050  * filesystem indicates there are no more space mappings, which means that this
0051  * function must be called in a loop that continues as long it returns a
0052  * positive value.  If 0 or a negative value is returned, the caller must not
0053  * return to the loop body.  Within a loop body, there are two ways to break out
0054  * of the loop body:  leave @iter.processed unchanged, or set it to a negative
0055  * errno.
0056  */
0057 int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
0058 {
0059     int ret;
0060
0061     if (iter->iomap.length && ops->iomap_end) {
0062         ret = ops->iomap_end(iter->inode, iter->pos, iomap_length(iter),
0063                 iter->processed > 0 ? iter->processed : 0,
0064                 iter->flags, &iter->iomap);
0065         if (ret < 0 && !iter->processed)
0066             return ret;
0067     }
0068
0069     trace_iomap_iter(iter, ops, _RET_IP_);
0070     ret = iomap_iter_advance(iter);
0071     if (ret <= 0)
0072         return ret;
0073
0074     ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,
0075                    &iter->iomap, &iter->srcmap);
0076     if (ret < 0)
0077         return ret;
0078     iomap_iter_done(iter);
0079     return 1;
0080 }