[PATCH v5 3/5] mm/readahead: Make space in struct file_ra_state
From: Ryan Roberts <ryan.roberts@arm.com>
Date: 2025-06-09 09:27:47
Also in:
linux-fsdevel, linux-mm, lkml
Subsystem:
filesystems (vfs and infrastructure), memory management, page cache, the rest · Maintainers:
Alexander Viro, Christian Brauner, Andrew Morton, Matthew Wilcox, Jan Kara, Linus Torvalds
We need to be able to store the preferred folio order associated with a readahead request in the struct file_ra_state so that we can more accurately increase the order across subsequent readahead requests. But struct file_ra_state is per-struct file, so we don't really want to increase it's size. mmap_miss is currently 32 bits but it is only counted up to 10 * MMAP_LOTSAMISS, which is currently defined as 1000. So 16 bits should be plenty. Redefine it to unsigned short, making room for order as unsigned short in follow up commit. Acked-by: David Hildenbrand <redacted> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> --- include/linux/fs.h | 2 +- mm/filemap.c | 11 ++++++----- 2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 05abdabe9db7..87e7d5790e43 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -1052,7 +1052,7 @@ struct file_ra_state { unsigned int size; unsigned int async_size; unsigned int ra_pages; - unsigned int mmap_miss; + unsigned short mmap_miss; loff_t prev_pos; };
diff --git a/mm/filemap.c b/mm/filemap.c
index a6459874bb2a..7bb4ffca8487 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c@@ -3217,7 +3217,7 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) DEFINE_READAHEAD(ractl, file, ra, mapping, vmf->pgoff); struct file *fpin = NULL; unsigned long vm_flags = vmf->vma->vm_flags; - unsigned int mmap_miss; + unsigned short mmap_miss; #ifdef CONFIG_TRANSPARENT_HUGEPAGE /* Use the readahead code, even if readahead is disabled */
@@ -3285,7 +3285,7 @@ static struct file *do_async_mmap_readahead(struct vm_fault *vmf, struct file_ra_state *ra = &file->f_ra; DEFINE_READAHEAD(ractl, file, ra, file->f_mapping, vmf->pgoff); struct file *fpin = NULL; - unsigned int mmap_miss; + unsigned short mmap_miss; /* If we don't want any read-ahead, don't bother */ if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages)
@@ -3605,7 +3605,7 @@ static struct folio *next_uptodate_folio(struct xa_state *xas, static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, struct folio *folio, unsigned long start, unsigned long addr, unsigned int nr_pages, - unsigned long *rss, unsigned int *mmap_miss) + unsigned long *rss, unsigned short *mmap_miss) { vm_fault_t ret = 0; struct page *page = folio_page(folio, start);
@@ -3667,7 +3667,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, static vm_fault_t filemap_map_order0_folio(struct vm_fault *vmf, struct folio *folio, unsigned long addr, - unsigned long *rss, unsigned int *mmap_miss) + unsigned long *rss, unsigned short *mmap_miss) { vm_fault_t ret = 0; struct page *page = &folio->page;
@@ -3709,7 +3709,8 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, struct folio *folio; vm_fault_t ret = 0; unsigned long rss = 0; - unsigned int nr_pages = 0, mmap_miss = 0, mmap_miss_saved, folio_type; + unsigned int nr_pages = 0, folio_type; + unsigned short mmap_miss = 0, mmap_miss_saved; rcu_read_lock(); folio = next_uptodate_folio(&xas, mapping, end_pgoff);
--
2.43.0