[PATCH v2 1/7] iomap: split out iomap check and reset logic from iter advance

Brian Foster
2025-01-22T13:32:26Z

In preparation for more granular iomap_iter advancing, break out
some of the logic associated with higher level iteration from
iomap_advance_iter(). Specifically, factor the iomap reset code into
a separate helper and lift the iomap.length check into the calling
code, similar to how ->iomap_end() calls are handled.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/iomap/iter.c | 49 ++++++++++++++++++++++++++-----------------------
1 file changed, 26 insertions(+), 23 deletions(-)

diff --git a/fs/iomap/iter.c b/fs/iomap/iter.c
index 3790918646af..731ea7267f27 100644
--- a/fs/iomap/iter.c
+++ b/fs/iomap/iter.c
@@ -7,6 +7,13 @@
#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.
*
@@ -14,32 +21,24 @@
* 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. iter->processed = 0). Hence the
- * "finished iterating" case needs to distinguish between
- * (processed = 0) meaning we are done and (processed = 0 && stale) meaning we
- * need to remap the entire remaining range.
+ * 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)
+static inline int iomap_iter_advance(struct iomap_iter *iter, s64 count)
{
bool stale = iter->iomap.flags & IOMAP_F_STALE;
int ret = 1;

- /* handle the previous iteration (if any) */
- if (iter->iomap.length) {
- if (iter->processed < 0)
- return iter->processed;
- if (WARN_ON_ONCE(iter->processed > iomap_length(iter)))
- return -EIO;
- iter->pos += iter->processed;
- iter->len -= iter->processed;
- if (!iter->len || (!iter->processed && !stale))
- ret = 0;
- }
+ if (count < 0)
+ return count;
+ if (WARN_ON_ONCE(count > iomap_length(iter)))
+ return -EIO;
+ iter->pos += count;
+ iter->len -= count;
+ if (!iter->len || (!count && !stale))
+ ret = 0;

- /* clear the per iteration state */
- iter->processed = 0;
- memset(&iter->iomap, 0, sizeof(iter->iomap));
- memset(&iter->srcmap, 0, sizeof(iter->srcmap));
return ret;
}

@@ -82,10 +81,14 @@ int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
return ret;
}

+ /* advance and clear state from the previous iteration */
trace_iomap_iter(iter, ops, _RET_IP_);
- ret = iomap_iter_advance(iter);
- if (ret <= 0)
- return ret;
+ if (iter->iomap.length) {
+ ret = iomap_iter_advance(iter, iter->processed);
+ iomap_iter_reset_iomap(iter);
+ if (ret <= 0)
+ return ret;
+ }

ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,
&iter->iomap, &iter->srcmap);
--
2.47.1