Commit 60aac486 authored by Vishal Moola (Oracle)'s avatar Vishal Moola (Oracle) Committed by Andrew Morton
Browse files

ramfs: convert ramfs_nommu_get_unmapped_area() to use filemap_get_folios_contig() 

Convert to use folios throughout.  This is in preparation for the removal
for find_get_pages_contig().  Now also supports large folios.

The initial version of this function set the page_address to be returned
after finishing all the checks.  Since folio_batches have a maximum of 15
folios, the function had to be modified to support getting and checking up
to lpages, 15 pages at a time while still returning the initial page
address.  Now the function sets ret as soon as the first batch arrives,
and updates it only if a check fails.

The physical adjacency check utilizes the page frame numbers.  The page
frame number of each folio must be nr_pages away from the first folio.

Link: https://lkml.kernel.org/r/20220824004023.77310-7-vishal.moola@gmail.com


Signed-off-by: default avatarVishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.com>
Cc: David Sterba <dsterb@suse.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 24a1efb4

fs/ramfs/file-nommu.c

+29 −21
Original line number Diff line number Diff line
@@ -203,9 +203,9 @@ static unsigned long ramfs_nommu_get_unmapped_area(struct file *file, 
					    unsigned long addr, unsigned long len,

					    unsigned long pgoff, unsigned long flags)

{

	unsigned long maxpages, lpages, nr, loop, ret;

	unsigned long maxpages, lpages, nr_folios, loop, ret, nr_pages, pfn;

	struct inode *inode = file_inode(file);

	struct page **pages = NULL, **ptr, *page;

	struct folio_batch fbatch;

	loff_t isize;



	/* the mapping mustn't extend beyond the EOF */
@@ -221,31 +221,39 @@ static unsigned long ramfs_nommu_get_unmapped_area(struct file *file, 
		goto out;



	/* gang-find the pages */

	pages = kcalloc(lpages, sizeof(struct page *), GFP_KERNEL);

	if (!pages)

		goto out_free;



	nr = find_get_pages_contig(inode->i_mapping, pgoff, lpages, pages);

	if (nr != lpages)

		goto out_free_pages; /* leave if some pages were missing */

	folio_batch_init(&fbatch);

	nr_pages = 0;

repeat:

	nr_folios = filemap_get_folios_contig(inode->i_mapping, &pgoff,

			ULONG_MAX, &fbatch);

	if (!nr_folios) {

		ret = -ENOSYS;

		return ret;

	}



	if (ret == -ENOSYS) {

		ret = (unsigned long) folio_address(fbatch.folios[0]);

		pfn = folio_pfn(fbatch.folios[0]);

	}

	/* check the pages for physical adjacency */

	ptr = pages;

	page = *ptr++;

	page++;

	for (loop = lpages; loop > 1; loop--)

		if (*ptr++ != page++)

			goto out_free_pages;

	for (loop = 0; loop < nr_folios; loop++) {

		if (pfn + nr_pages != folio_pfn(fbatch.folios[loop])) {

			ret = -ENOSYS;

			goto out_free; /* leave if not physical adjacent */

		}

		nr_pages += folio_nr_pages(fbatch.folios[loop]);

		if (nr_pages >= lpages)

			goto out_free; /* successfully found desired pages*/

	}



	if (nr_pages < lpages) {

		folio_batch_release(&fbatch);

		goto repeat; /* loop if pages are missing */

	}

	/* okay - all conditions fulfilled */

	ret = (unsigned long) page_address(pages[0]);



out_free_pages:

	ptr = pages;

	for (loop = nr; loop > 0; loop--)

		put_page(*ptr++);

out_free:

	kfree(pages);

	folio_batch_release(&fbatch);

out:

	return ret;

}