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-rw-r--r--include/linux/pagemap.h1
-rw-r--r--mm/filemap.c75
2 files changed, 16 insertions, 60 deletions
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index b477a70cc2e4..bcf909d0de5f 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -239,6 +239,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
#define FGP_WRITE 0x00000008
#define FGP_NOFS 0x00000010
#define FGP_NOWAIT 0x00000020
+#define FGP_FOR_MMAP 0x00000040
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
int fgp_flags, gfp_t cache_gfp_mask);
diff --git a/mm/filemap.c b/mm/filemap.c
index ec6566ffbd90..64d014f940e9 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1587,6 +1587,9 @@ EXPORT_SYMBOL(find_lock_entry);
* @gfp_mask and added to the page cache and the VM's LRU
* list. The page is returned locked and with an increased
* refcount.
+ * - FGP_FOR_MMAP: Similar to FGP_CREAT, only we want to allow the caller to do
+ * its own locking dance if the page is already in cache, or unlock the page
+ * before returning if we had to add the page to pagecache.
*
* If FGP_LOCK or FGP_CREAT are specified then the function may sleep even
* if the GFP flags specified for FGP_CREAT are atomic.
@@ -1641,7 +1644,7 @@ no_page:
if (!page)
return NULL;
- if (WARN_ON_ONCE(!(fgp_flags & FGP_LOCK)))
+ if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
fgp_flags |= FGP_LOCK;
/* Init accessed so avoid atomic mark_page_accessed later */
@@ -1655,6 +1658,13 @@ no_page:
if (err == -EEXIST)
goto repeat;
}
+
+ /*
+ * add_to_page_cache_lru locks the page, and for mmap we expect
+ * an unlocked page.
+ */
+ if (page && (fgp_flags & FGP_FOR_MMAP))
+ unlock_page(page);
}
return page;
@@ -2379,41 +2389,6 @@ out:
EXPORT_SYMBOL(generic_file_read_iter);
#ifdef CONFIG_MMU
-/**
- * page_cache_read - adds requested page to the page cache if not already there
- * @file: file to read
- * @offset: page index
- * @gfp_mask: memory allocation flags
- *
- * This adds the requested page to the page cache if it isn't already there,
- * and schedules an I/O to read in its contents from disk.
- *
- * Return: %0 on success, negative error code otherwise.
- */
-static int page_cache_read(struct file *file, pgoff_t offset, gfp_t gfp_mask)
-{
- struct address_space *mapping = file->f_mapping;
- struct page *page;
- int ret;
-
- do {
- page = __page_cache_alloc(gfp_mask);
- if (!page)
- return -ENOMEM;
-
- ret = add_to_page_cache_lru(page, mapping, offset, gfp_mask);
- if (ret == 0)
- ret = mapping->a_ops->readpage(file, page);
- else if (ret == -EEXIST)
- ret = 0; /* losing race to add is OK */
-
- put_page(page);
-
- } while (ret == AOP_TRUNCATED_PAGE);
-
- return ret;
-}
-
#define MMAP_LOTSAMISS (100)
/*
@@ -2539,9 +2514,11 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
ret = VM_FAULT_MAJOR;
retry_find:
- page = find_get_page(mapping, offset);
+ page = pagecache_get_page(mapping, offset,
+ FGP_CREAT|FGP_FOR_MMAP,
+ vmf->gfp_mask);
if (!page)
- goto no_cached_page;
+ return vmf_error(-ENOMEM);
}
if (!lock_page_or_retry(page, vmf->vma->vm_mm, vmf->flags)) {
@@ -2578,28 +2555,6 @@ retry_find:
vmf->page = page;
return ret | VM_FAULT_LOCKED;
-no_cached_page:
- /*
- * We're only likely to ever get here if MADV_RANDOM is in
- * effect.
- */
- error = page_cache_read(file, offset, vmf->gfp_mask);
-
- /*
- * The page we want has now been added to the page cache.
- * In the unlikely event that someone removed it in the
- * meantime, we'll just come back here and read it again.
- */
- if (error >= 0)
- goto retry_find;
-
- /*
- * An error return from page_cache_read can result if the
- * system is low on memory, or a problem occurs while trying
- * to schedule I/O.
- */
- return vmf_error(error);
-
page_not_uptodate:
/*
* Umm, take care of errors if the page isn't up-to-date.