[PATCH v4 09/10] fuse: support large folios for readahead

[Joanne Koong <joannelkoong@xxxxxxxxx>]

Add support for folios larger than one page size for readahead.

Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
 fs/fuse/file.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index a178aee87e74..5c98dcc337d4 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -963,14 +963,13 @@ static void fuse_readpages_end(struct fuse_mount *fm, struct fuse_args *args,
 	fuse_io_free(ia);
 }
 
-static void fuse_send_readpages(struct fuse_io_args *ia, struct file *file)
+static void fuse_send_readpages(struct fuse_io_args *ia, struct file *file,
+				unsigned int count)
 {
 	struct fuse_file *ff = file->private_data;
 	struct fuse_mount *fm = ff->fm;
 	struct fuse_args_pages *ap = &ia->ap;
 	loff_t pos = folio_pos(ap->folios[0]);
-	/* Currently, all folios in FUSE are one page */
-	size_t count = ap->num_folios << PAGE_SHIFT;
 	ssize_t res;
 	int err;
 
@@ -1008,6 +1007,7 @@ static void fuse_readahead(struct readahead_control *rac)
 	unsigned int max_pages, nr_pages;
 	pgoff_t first = readahead_index(rac);
 	pgoff_t last = first + readahead_count(rac) - 1;
+	struct folio *folio = NULL;
 
 	if (fuse_is_bad(inode))
 		return;
@@ -1031,8 +1031,8 @@ static void fuse_readahead(struct readahead_control *rac)
 	while (nr_pages) {
 		struct fuse_io_args *ia;
 		struct fuse_args_pages *ap;
-		struct folio *folio;
 		unsigned cur_pages = min(max_pages, nr_pages);
+		unsigned int pages = 0;
 
 		if (fc->num_background >= fc->congestion_threshold &&
 		    rac->ra->async_size >= readahead_count(rac))
@@ -1047,14 +1047,27 @@ static void fuse_readahead(struct readahead_control *rac)
 			return;
 		ap = &ia->ap;
 
-		while (ap->num_folios < cur_pages) {
-			folio = readahead_folio(rac);
+		while (pages < cur_pages) {
+			unsigned int folio_pages;
+
+			if (!folio)
+				folio = readahead_folio(rac);
+
+			folio_pages = folio_nr_pages(folio);
+			if (folio_pages > cur_pages - pages) {
+				if (!pages)
+					return;
+				break;
+			}
+
 			ap->folios[ap->num_folios] = folio;
 			ap->descs[ap->num_folios].length = folio_size(folio);
 			ap->num_folios++;
+			pages += folio_pages;
+			folio = NULL;
 		}
-		fuse_send_readpages(ia, rac->file);
-		nr_pages -= cur_pages;
+		fuse_send_readpages(ia, rac->file, pages << PAGE_SHIFT);
+		nr_pages -= pages;
 	}
 }
 
-- 
2.43.5