[PATCH 01/10] iomap: advance the iter directly on buffered read

Brian Foster
2025-02-12T13:54:50Z

iomap buffered read advances the iter via iter.processed. To
continue separating iter advance from return status, update
iomap_readpage_iter() to advance the iter instead of returning the
number of bytes processed. In turn, drop the offset parameter and
sample the updated iter->pos at the start of the function. Update
the callers to loop based on remaining length in the current
iteration instead of number of bytes processed.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
fs/iomap/buffered-io.c | 44 +++++++++++++++++++-----------------------
1 file changed, 20 insertions(+), 24 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index ec227b45f3aa..44a366736289 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -366,12 +366,12 @@ static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter,
pos >= i_size_read(iter->inode);
}

-static loff_t iomap_readpage_iter(const struct iomap_iter *iter,
- struct iomap_readpage_ctx *ctx, loff_t offset)
+static loff_t iomap_readpage_iter(struct iomap_iter *iter,
+ struct iomap_readpage_ctx *ctx)
{
const struct iomap *iomap = &iter->iomap;
- loff_t pos = iter->pos + offset;
- loff_t length = iomap_length(iter) - offset;
+ loff_t pos = iter->pos;
+ loff_t length = iomap_length(iter);
struct folio *folio = ctx->cur_folio;
struct iomap_folio_state *ifs;
loff_t orig_pos = pos;
@@ -438,25 +438,22 @@ static loff_t iomap_readpage_iter(const struct iomap_iter *iter,
* we can skip trailing ones as they will be handled in the next
* iteration.
*/
- return pos - orig_pos + plen;
+ length = pos - orig_pos + plen;
+ return iomap_iter_advance(iter, &length);
}

-static loff_t iomap_read_folio_iter(const struct iomap_iter *iter,
+static loff_t iomap_read_folio_iter(struct iomap_iter *iter,
struct iomap_readpage_ctx *ctx)
{
- struct folio *folio = ctx->cur_folio;
- size_t offset = offset_in_folio(folio, iter->pos);
- loff_t length = min_t(loff_t, folio_size(folio) - offset,
- iomap_length(iter));
- loff_t done, ret;
-
- for (done = 0; done < length; done += ret) {
- ret = iomap_readpage_iter(iter, ctx, done);
- if (ret <= 0)
+ loff_t ret;
+
+ while (iomap_length(iter)) {
+ ret = iomap_readpage_iter(iter, ctx);
+ if (ret)
return ret;
}

- return done;
+ return 0;
}

int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops)
@@ -493,15 +490,14 @@ int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops)
}
EXPORT_SYMBOL_GPL(iomap_read_folio);

-static loff_t iomap_readahead_iter(const struct iomap_iter *iter,
+static loff_t iomap_readahead_iter(struct iomap_iter *iter,
struct iomap_readpage_ctx *ctx)
{
- loff_t length = iomap_length(iter);
- loff_t done, ret;
+ loff_t ret;

- for (done = 0; done < length; done += ret) {
+ while (iomap_length(iter) > 0) {
if (ctx->cur_folio &&
- offset_in_folio(ctx->cur_folio, iter->pos + done) == 0) {
+ offset_in_folio(ctx->cur_folio, iter->pos) == 0) {
if (!ctx->cur_folio_in_bio)
folio_unlock(ctx->cur_folio);
ctx->cur_folio = NULL;
@@ -510,12 +506,12 @@ static loff_t iomap_readahead_iter(const struct iomap_iter *iter,
ctx->cur_folio = readahead_folio(ctx->rac);
ctx->cur_folio_in_bio = false;
}
- ret = iomap_readpage_iter(iter, ctx, done);
- if (ret <= 0)
+ ret = iomap_readpage_iter(iter, ctx);
+ if (ret)
return ret;
}

- return done;
+ return 0;
}

/**
--
2.48.1