iomap: Add iomap_get_folio helper

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>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index d4b444e44861cdc50bb1b10f62571aef6fffddec..de4a8e5f721a54d32305109536108c125345516d 100644 (file)
--- 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 ecf815b34d510d96a489d2095540632e5a8983b5..188d14e786a41c87701205e1aea5787e888a721d 100644 (file)
--- 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,