[PATCH v5 4/9] iomap: Add iomap_get_folio helper

Andreas Gruenbacher
2022-12-31T15:11:14Z

Add an iomap_get_folio() helper that gets a folio reference based on
an iomap iterator and an offset into the address space. Use it in
iomap_write_begin().

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
fs/iomap/buffered-io.c | 39 ++++++++++++++++++++++++++++++---------
include/linux/iomap.h | 1 +
2 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 2a9bab4f3c79..b84838d2b5d8 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -457,6 +457,33 @@ bool iomap_is_partially_uptodate(struct folio *folio, size_t from, size_t count)
}
EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);

+/**
+ * iomap_get_folio - get a folio reference for writing
+ * @iter: iteration structure
+ * @pos: start offset of write
+ *
+ * Returns a locked reference to the folio at @pos, or an error pointer if the
+ * folio could not be obtained.
+ */
+struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos)
+{
+ unsigned fgp = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE | FGP_NOFS;
+ struct folio *folio;
+
+ if (iter->flags & IOMAP_NOWAIT)
+ fgp |= FGP_NOWAIT;
+
+ folio = __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
+ fgp, mapping_gfp_mask(iter->inode->i_mapping));
+ if (folio)
+ return folio;
+
+ if (iter->flags & IOMAP_NOWAIT)
+ return ERR_PTR(-EAGAIN);
+ return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL_GPL(iomap_get_folio);
+
bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags)
{
trace_iomap_release_folio(folio->mapping->host, folio_pos(folio),
@@ -603,12 +630,8 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
const struct iomap_page_ops *page_ops = iter->iomap.page_ops;
const struct iomap *srcmap = iomap_iter_srcmap(iter);
struct folio *folio;
- unsigned fgp = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE | FGP_NOFS;
int status = 0;

- if (iter->flags & IOMAP_NOWAIT)
- fgp |= FGP_NOWAIT;
-
BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length);
if (srcmap != &iter->iomap)
BUG_ON(pos + len > srcmap->offset + srcmap->length);
@@ -625,12 +648,10 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
return status;
}

- folio = __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
- fgp, mapping_gfp_mask(iter->inode->i_mapping));
- if (!folio) {
- status = (iter->flags & IOMAP_NOWAIT) ? -EAGAIN : -ENOMEM;
+ folio = iomap_get_folio(iter, pos);
+ if (IS_ERR(folio)) {
iomap_put_folio(iter, pos, 0, NULL);
- return status;
+ return PTR_ERR(folio);
}

/*
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 10ec36f373f4..e5732cc5716b 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -261,6 +261,7 @@ int iomap_file_buffered_write_punch_delalloc(struct inode *inode,
int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops);
void iomap_readahead(struct readahead_control *, const struct iomap_ops *ops);
bool iomap_is_partially_uptodate(struct folio *, size_t from, size_t count);
+struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos);
bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags);
void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len);
int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
--
2.38.1