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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2010 Red Hat, Inc.
* Copyright (c) 2016-2021 Christoph Hellwig.
*/
#include <linux/fs.h>
#include <linux/iomap.h>
#include "trace.h"
static inline void iomap_iter_reset_iomap(struct iomap_iter *iter)
{
iter->processed = 0;
memset(&iter->iomap, 0, sizeof(iter->iomap));
memset(&iter->srcmap, 0, sizeof(iter->srcmap));
}
/*
* Advance to the next range we need to map.
*
* If the iomap is marked IOMAP_F_STALE, it means the existing map was not fully
* processed - it was aborted because the extent the iomap spanned may have been
* changed during the operation. In this case, the iteration behaviour is to
* remap the unprocessed range of the iter, and that means we may need to remap
* even when we've made no progress (i.e. count = 0). Hence the "finished
* iterating" case needs to distinguish between (count = 0) meaning we are done
* and (count = 0 && stale) meaning we need to remap the entire remaining range.
*/
static inline int iomap_iter_advance(struct iomap_iter *iter, s64 count)
{
if (WARN_ON_ONCE(count > iomap_length(iter)))
return -EIO;
iter->pos += count;
iter->len -= count;
return 0;
}
static inline void iomap_iter_done(struct iomap_iter *iter)
{
WARN_ON_ONCE(iter->iomap.offset > iter->pos);
WARN_ON_ONCE(iter->iomap.length == 0);
WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos);
WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_STALE);
trace_iomap_iter_dstmap(iter->inode, &iter->iomap);
if (iter->srcmap.type != IOMAP_HOLE)
trace_iomap_iter_srcmap(iter->inode, &iter->srcmap);
}
/**
* iomap_iter - iterate over a ranges in a file
* @iter: iteration structue
* @ops: iomap ops provided by the file system
*
* Iterate over filesystem-provided space mappings for the provided file range.
*
* This function handles cleanup of resources acquired for iteration when the
* filesystem indicates there are no more space mappings, which means that this
* function must be called in a loop that continues as long it returns a
* positive value. If 0 or a negative value is returned, the caller must not
* return to the loop body. Within a loop body, there are two ways to break out
* of the loop body: leave @iter.processed unchanged, or set it to a negative
* errno.
*/
int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
{
bool stale = iter->iomap.flags & IOMAP_F_STALE;
s64 processed;
int ret;
trace_iomap_iter(iter, ops, _RET_IP_);
if (!iter->iomap.length)
goto begin;
if (ops->iomap_end) {
ret = ops->iomap_end(iter->inode, iter->pos, iomap_length(iter),
iter->processed > 0 ? iter->processed : 0,
iter->flags, &iter->iomap);
if (ret < 0 && !iter->processed)
return ret;
}
processed = iter->processed;
if (processed < 0) {
iomap_iter_reset_iomap(iter);
return processed;
}
/*
* Advance the iter and clear state from the previous iteration. Use
* iter->len to determine whether to continue onto the next mapping.
* Explicitly terminate in the case where the current iter has not
* advanced at all (i.e. no work was done for some reason) unless the
* mapping has been marked stale and needs to be reprocessed.
*/
ret = iomap_iter_advance(iter, processed);
if (!ret && iter->len > 0)
ret = 1;
if (ret > 0 && !iter->processed && !stale)
ret = 0;
iomap_iter_reset_iomap(iter);
if (ret <= 0)
return ret;
begin:
ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,
&iter->iomap, &iter->srcmap);
if (ret < 0)
return ret;
iomap_iter_done(iter);
return 1;
}
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