[PATCH v3 0/7] Convert to filemap_get_folios_contig()

[PATCH v3 0/7] Convert to filemap_get_folios_contig()

[Vishal Moola (Oracle)]

This patch series replaces find_get_pages_contig() with
filemap_get_folios_contig(). I've run xfstests on btrfs. I've also
tested the ramfs changes. I ran some xfstests on nilfs2, and its
seemingly fine although more testing may be beneficial.
---

v2:
  - Removed an unused label in nilfs2
  - Reported-by: kernel test robot <lkp@intel.com>

v3:
  - Fixed minor style issues in btrfs patches
  - Fixed an issue in nilfs2 regarding the block index
  - "nr" renamed to "nr_folios" in nilfs2 and ramfs for clarity
  - Got some Acked-by's

Vishal Moola (Oracle) (7):
  filemap: Add filemap_get_folios_contig()
  btrfs: Convert __process_pages_contig() to use
    filemap_get_folios_contig()
  btrfs: Convert end_compressed_writeback() to use filemap_get_folios()
  btrfs: Convert process_page_range() to use filemap_get_folios_contig()
  nilfs2: Convert nilfs_find_uncommited_extent() to use
    filemap_get_folios_contig()
  ramfs: Convert ramfs_nommu_get_unmapped_area() to use
    filemap_get_folios_contig()
  filemap: Remove find_get_pages_contig()

 fs/btrfs/compression.c           | 31 +++++++-------
 fs/btrfs/extent_io.c             | 33 +++++++--------
 fs/btrfs/subpage.c               |  2 +-
 fs/btrfs/tests/extent-io-tests.c | 32 +++++++-------
 fs/nilfs2/page.c                 | 45 ++++++++------------
 fs/ramfs/file-nommu.c            | 50 ++++++++++++----------
 include/linux/pagemap.h          |  4 +-
 mm/filemap.c                     | 71 +++++++++++++++++++-------------
 8 files changed, 139 insertions(+), 129 deletions(-)

-- 
2.36.1

[PATCH v3 1/7] filemap: Add filemap_get_folios_contig()

[Vishal Moola (Oracle)]

This function is meant to replace find_get_pages_contig().

Unlike find_get_pages_contig(), filemap_get_folios_contig() no
longer takes in a target number of pages to find - It returns up to 15
contiguous folios.

To be more consistent with filemap_get_folios(), filemap_get_folios_contig()
now also updates the start index passed in, and takes an end index.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 include/linux/pagemap.h |  2 ++
 mm/filemap.c            | 73 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index cc9adbaddb59..951936a2be1d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -720,6 +720,8 @@ static inline struct page *find_subpage(struct page *head, pgoff_t index)
 
 unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start,
 		pgoff_t end, struct folio_batch *fbatch);
+unsigned filemap_get_folios_contig(struct address_space *mapping,
+		pgoff_t *start, pgoff_t end, struct folio_batch *fbatch);
 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
 			       unsigned int nr_pages, struct page **pages);
 unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
diff --git a/mm/filemap.c b/mm/filemap.c
index 8ccb868c3d95..8167bcc96e37 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2196,6 +2196,79 @@ bool folio_more_pages(struct folio *folio, pgoff_t index, pgoff_t max)
 	return index < folio->index + folio_nr_pages(folio) - 1;
 }
 
+/**
+ * filemap_get_folios_contig - Get a batch of contiguous folios
+ * @mapping:	The address_space to search
+ * @start:	The starting page index
+ * @end:	The final page index (inclusive)
+ * @fbatch:	The batch to fill
+ *
+ * filemap_get_folios_contig() works exactly like filemap_get_folios(),
+ * except the returned folios are guaranteed to be contiguous. This may
+ * not return all contiguous folios if the batch gets filled up.
+ *
+ * Return: The number of folios found.
+ * Also update @start to be positioned for traversal of the next folio.
+ */
+
+unsigned filemap_get_folios_contig(struct address_space *mapping,
+		pgoff_t *start, pgoff_t end, struct folio_batch *fbatch)
+{
+	XA_STATE(xas, &mapping->i_pages, *start);
+	unsigned long nr;
+	struct folio *folio;
+
+	rcu_read_lock();
+
+	for (folio = xas_load(&xas); folio && xas.xa_index <= end;
+			folio = xas_next(&xas)) {
+		if (xas_retry(&xas, folio))
+			continue;
+		/*
+		 * If the entry has been swapped out, we can stop looking.
+		 * No current caller is looking for DAX entries.
+		 */
+		if (xa_is_value(folio))
+			goto update_start;
+
+		if (!folio_try_get_rcu(folio))
+			goto retry;
+
+		if (unlikely(folio != xas_reload(&xas)))
+			goto put_folio;
+
+		if (!folio_batch_add(fbatch, folio)) {
+			nr = folio_nr_pages(folio);
+
+			if (folio_test_hugetlb(folio))
+				nr = 1;
+			*start = folio->index + nr;
+			goto out;
+		}
+		continue;
+put_folio:
+		folio_put(folio);
+
+retry:
+		xas_reset(&xas);
+	}
+
+update_start:
+	nr = folio_batch_count(fbatch);
+
+	if (nr) {
+		folio = fbatch->folios[nr - 1];
+		if (folio_test_hugetlb(folio))
+			*start = folio->index + 1;
+		else
+			*start = folio->index + folio_nr_pages(folio);
+	}
+out:
+	rcu_read_unlock();
+	return folio_batch_count(fbatch);
+}
+EXPORT_SYMBOL(filemap_get_folios_contig);
+
 /**
  * find_get_pages_contig - gang contiguous pagecache lookup
  * @mapping:	The address_space to search
-- 
2.36.1

[PATCH v3 2/7] btrfs: Convert __process_pages_contig() to use filemap_get_folios_contig()

[Vishal Moola (Oracle)]

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

Since we may receive more than nr_pages pages, nr_pages may underflow.
Since nr_pages > 0 is equivalent to index <= end_index, we replaced it
with this check instead.

Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 fs/btrfs/extent_io.c | 33 +++++++++++++++------------------
 1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 8f6b544ae616..f16929bc531b 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1882,9 +1882,8 @@ static int __process_pages_contig(struct address_space *mapping,
 	pgoff_t start_index = start >> PAGE_SHIFT;
 	pgoff_t end_index = end >> PAGE_SHIFT;
 	pgoff_t index = start_index;
-	unsigned long nr_pages = end_index - start_index + 1;
 	unsigned long pages_processed = 0;
-	struct page *pages[16];
+	struct folio_batch fbatch;
 	int err = 0;
 	int i;
 
@@ -1893,16 +1892,17 @@ static int __process_pages_contig(struct address_space *mapping,
 		ASSERT(processed_end && *processed_end == start);
 	}
 
-	if ((page_ops & PAGE_SET_ERROR) && nr_pages > 0)
+	if ((page_ops & PAGE_SET_ERROR) && start_index <= end_index)
 		mapping_set_error(mapping, -EIO);
 
-	while (nr_pages > 0) {
-		int found_pages;
+	folio_batch_init(&fbatch);
+	while (index <= end_index) {
+		int found_folios;
+
+		found_folios = filemap_get_folios_contig(mapping, &index,
+				end_index, &fbatch);
 
-		found_pages = find_get_pages_contig(mapping, index,
-				     min_t(unsigned long,
-				     nr_pages, ARRAY_SIZE(pages)), pages);
-		if (found_pages == 0) {
+		if (found_folios == 0) {
 			/*
 			 * Only if we're going to lock these pages, we can find
 			 * nothing at @index.
@@ -1912,23 +1912,20 @@ static int __process_pages_contig(struct address_space *mapping,
 			goto out;
 		}
 
-		for (i = 0; i < found_pages; i++) {
+		for (i = 0; i < found_folios; i++) {
 			int process_ret;
-
+			struct folio *folio = fbatch.folios[i];
 			process_ret = process_one_page(fs_info, mapping,
-					pages[i], locked_page, page_ops,
+					&folio->page, locked_page, page_ops,
 					start, end);
 			if (process_ret < 0) {
-				for (; i < found_pages; i++)
-					put_page(pages[i]);
 				err = -EAGAIN;
+				folio_batch_release(&fbatch);
 				goto out;
 			}
-			put_page(pages[i]);
-			pages_processed++;
+			pages_processed += folio_nr_pages(folio);
 		}
-		nr_pages -= found_pages;
-		index += found_pages;
+		folio_batch_release(&fbatch);
 		cond_resched();
 	}
 out:
-- 
2.36.1

[PATCH v3 3/7] btrfs: Convert end_compressed_writeback() to use filemap_get_folios()

[Vishal Moola (Oracle)]

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

Since we may receive more than nr_pages pages, nr_pages may underflow.
Since nr_pages > 0 is equivalent to index <= end_index, we replaced it
with this check instead.

Also this function does not care about the pages being contiguous so we
can just use filemap_get_folios() to be more efficient.

Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 fs/btrfs/compression.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index f4564f32f6d9..e0f8839cdd94 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -8,6 +8,7 @@
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/pagemap.h>
+#include <linux/pagevec.h>
 #include <linux/highmem.h>
 #include <linux/kthread.h>
 #include <linux/time.h>
@@ -339,8 +340,7 @@ static noinline void end_compressed_writeback(struct inode *inode,
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	unsigned long index = cb->start >> PAGE_SHIFT;
 	unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT;
-	struct page *pages[16];
-	unsigned long nr_pages = end_index - index + 1;
+	struct folio_batch fbatch;
 	const int errno = blk_status_to_errno(cb->status);
 	int i;
 	int ret;
@@ -348,24 +348,23 @@ static noinline void end_compressed_writeback(struct inode *inode,
 	if (errno)
 		mapping_set_error(inode->i_mapping, errno);
 
-	while (nr_pages > 0) {
-		ret = find_get_pages_contig(inode->i_mapping, index,
-				     min_t(unsigned long,
-				     nr_pages, ARRAY_SIZE(pages)), pages);
-		if (ret == 0) {
-			nr_pages -= 1;
-			index += 1;
-			continue;
-		}
+	folio_batch_init(&fbatch);
+	while (index <= end_index) {
+		ret = filemap_get_folios(inode->i_mapping, &index, end_index,
+				&fbatch);
+
+		if (ret == 0)
+			return;
+
 		for (i = 0; i < ret; i++) {
+			struct folio *folio = fbatch.folios[i];
+
 			if (errno)
-				SetPageError(pages[i]);
-			btrfs_page_clamp_clear_writeback(fs_info, pages[i],
+				folio_set_error(folio);
+			btrfs_page_clamp_clear_writeback(fs_info, &folio->page,
 							 cb->start, cb->len);
-			put_page(pages[i]);
 		}
-		nr_pages -= ret;
-		index += ret;
+		folio_batch_release(&fbatch);
 	}
 	/* the inode may be gone now */
 }
-- 
2.36.1

[PATCH v3 4/7] btrfs: Convert process_page_range() to use filemap_get_folios_contig()

[Vishal Moola (Oracle)]

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

Since we may receive more than nr_pages pages, nr_pages may underflow.
Since nr_pages > 0 is equivalent to index <= end_index, we replaced it
with this check instead.

Also minor comment renaming for consistency in subpage.

Acked-by: David Sterba <dsterb@suse.com>
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 fs/btrfs/subpage.c               |  2 +-
 fs/btrfs/tests/extent-io-tests.c | 32 +++++++++++++++++---------------
 2 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c
index a105b291444f..6418c38c4b30 100644
--- a/fs/btrfs/subpage.c
+++ b/fs/btrfs/subpage.c
@@ -337,7 +337,7 @@ bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,
  *
  * Even with 0 returned, the page still need extra check to make sure
  * it's really the correct page, as the caller is using
- * find_get_pages_contig(), which can race with page invalidating.
+ * filemap_get_folios_contig(), which can race with page invalidating.
  */
 int btrfs_page_start_writer_lock(const struct btrfs_fs_info *fs_info,
 		struct page *page, u64 start, u32 len)
diff --git a/fs/btrfs/tests/extent-io-tests.c b/fs/btrfs/tests/extent-io-tests.c
index a232b15b8021..26b0c99f54b8 100644
--- a/fs/btrfs/tests/extent-io-tests.c
+++ b/fs/btrfs/tests/extent-io-tests.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/pagemap.h>
+#include <linux/pagevec.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/sizes.h>
@@ -20,39 +21,40 @@ static noinline int process_page_range(struct inode *inode, u64 start, u64 end,
 				       unsigned long flags)
 {
 	int ret;
-	struct page *pages[16];
+	struct folio_batch fbatch;
 	unsigned long index = start >> PAGE_SHIFT;
 	unsigned long end_index = end >> PAGE_SHIFT;
-	unsigned long nr_pages = end_index - index + 1;
 	int i;
 	int count = 0;
 	int loops = 0;
 
-	while (nr_pages > 0) {
-		ret = find_get_pages_contig(inode->i_mapping, index,
-				     min_t(unsigned long, nr_pages,
-				     ARRAY_SIZE(pages)), pages);
+	folio_batch_init(&fbatch);
+
+	while (index <= end_index) {
+		ret = filemap_get_folios_contig(inode->i_mapping, &index,
+				end_index, &fbatch);
 		for (i = 0; i < ret; i++) {
+			struct folio *folio = fbatch.folios[i];
+
 			if (flags & PROCESS_TEST_LOCKED &&
-			    !PageLocked(pages[i]))
+			    !folio_test_locked(folio))
 				count++;
-			if (flags & PROCESS_UNLOCK && PageLocked(pages[i]))
-				unlock_page(pages[i]);
-			put_page(pages[i]);
+			if (flags & PROCESS_UNLOCK && folio_test_locked(folio))
+				folio_unlock(folio);
 			if (flags & PROCESS_RELEASE)
-				put_page(pages[i]);
+				folio_put(folio);
 		}
-		nr_pages -= ret;
-		index += ret;
+		folio_batch_release(&fbatch);
 		cond_resched();
 		loops++;
 		if (loops > 100000) {
 			printk(KERN_ERR
-		"stuck in a loop, start %llu, end %llu, nr_pages %lu, ret %d\n",
-				start, end, nr_pages, ret);
+		"stuck in a loop, start %llu, end %llu, ret %d\n",
+				start, end, ret);
 			break;
 		}
 	}
+
 	return count;
 }
 
-- 
2.36.1

[PATCH v3 5/7] nilfs2: Convert nilfs_find_uncommited_extent() to use filemap_get_folios_contig()

[Vishal Moola (Oracle)]

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

Also cleaned up an unnecessary if statement - pvec.pages[0]->index > index
will always evaluate to false, and filemap_get_folios_contig() returns 0 if
there is no folio found at index.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 fs/nilfs2/page.c | 45 ++++++++++++++++++---------------------------
 1 file changed, 18 insertions(+), 27 deletions(-)

diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c
index 3267e96c256c..39b7eea2642a 100644
--- a/fs/nilfs2/page.c
+++ b/fs/nilfs2/page.c
@@ -480,41 +480,36 @@ unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
 					    sector_t start_blk,
 					    sector_t *blkoff)
 {
-	unsigned int i;
+	unsigned int i, nr_folios;
 	pgoff_t index;
-	unsigned int nblocks_in_page;
 	unsigned long length = 0;
-	sector_t b;
-	struct pagevec pvec;
-	struct page *page;
+	struct folio_batch fbatch;
+	struct folio *folio;
 
 	if (inode->i_mapping->nrpages == 0)
 		return 0;
 
 	index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
-	nblocks_in_page = 1U << (PAGE_SHIFT - inode->i_blkbits);
 
-	pagevec_init(&pvec);
+	folio_batch_init(&fbatch);
 
 repeat:
-	pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
-					pvec.pages);
-	if (pvec.nr == 0)
+	nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
+			&fbatch);
+	if (nr_folios == 0)
 		return length;
 
-	if (length > 0 && pvec.pages[0]->index > index)
-		goto out;
-
-	b = pvec.pages[0]->index << (PAGE_SHIFT - inode->i_blkbits);
 	i = 0;
 	do {
-		page = pvec.pages[i];
+		folio = fbatch.folios[i];
 
-		lock_page(page);
-		if (page_has_buffers(page)) {
+		folio_lock(folio);
+		if (folio_buffers(folio)) {
 			struct buffer_head *bh, *head;
+			sector_t b;
 
-			bh = head = page_buffers(page);
+			b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
+			bh = head = folio_buffers(folio);
 			do {
 				if (b < start_blk)
 					continue;
@@ -529,21 +524,17 @@ unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
 		} else {
 			if (length > 0)
 				goto out_locked;
-
-			b += nblocks_in_page;
 		}
-		unlock_page(page);
+		folio_unlock(folio);
 
-	} while (++i < pagevec_count(&pvec));
+	} while (++i < nr_folios);
 
-	index = page->index + 1;
-	pagevec_release(&pvec);
+	folio_batch_release(&fbatch);
 	cond_resched();
 	goto repeat;
 
 out_locked:
-	unlock_page(page);
-out:
-	pagevec_release(&pvec);
+	folio_unlock(folio);
+	folio_batch_release(&fbatch);
 	return length;
 }
-- 
2.36.1

[PATCH v3 6/7] ramfs: Convert ramfs_nommu_get_unmapped_area() to use filemap_get_folios_contig()

[Vishal Moola (Oracle)]

Converted 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.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
---
 fs/ramfs/file-nommu.c | 50 +++++++++++++++++++++++++------------------
 1 file changed, 29 insertions(+), 21 deletions(-)

diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
index ba3525ccc27e..cb240eac5036 100644
--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -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;
 }
-- 
2.36.1

[PATCH v3 7/7] filemap: Remove find_get_pages_contig()

[Vishal Moola (Oracle)]

All callers of find_get_pages_contig() have been removed, so it is no
longer needed.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 include/linux/pagemap.h |  2 --
 mm/filemap.c            | 60 -----------------------------------------
 2 files changed, 62 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 951936a2be1d..a04a645b64e9 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -722,8 +722,6 @@ unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start,
 		pgoff_t end, struct folio_batch *fbatch);
 unsigned filemap_get_folios_contig(struct address_space *mapping,
 		pgoff_t *start, pgoff_t end, struct folio_batch *fbatch);
-unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
-			       unsigned int nr_pages, struct page **pages);
 unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
 			pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
 			struct page **pages);
diff --git a/mm/filemap.c b/mm/filemap.c
index 8167bcc96e37..af5a4b5f866d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2269,66 +2269,6 @@ unsigned filemap_get_folios_contig(struct address_space *mapping,
 }
 EXPORT_SYMBOL(filemap_get_folios_contig);
 
-/**
- * find_get_pages_contig - gang contiguous pagecache lookup
- * @mapping:	The address_space to search
- * @index:	The starting page index
- * @nr_pages:	The maximum number of pages
- * @pages:	Where the resulting pages are placed
- *
- * find_get_pages_contig() works exactly like find_get_pages_range(),
- * except that the returned number of pages are guaranteed to be
- * contiguous.
- *
- * Return: the number of pages which were found.
- */
-unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
-			       unsigned int nr_pages, struct page **pages)
-{
-	XA_STATE(xas, &mapping->i_pages, index);
-	struct folio *folio;
-	unsigned int ret = 0;
-
-	if (unlikely(!nr_pages))
-		return 0;
-
-	rcu_read_lock();
-	for (folio = xas_load(&xas); folio; folio = xas_next(&xas)) {
-		if (xas_retry(&xas, folio))
-			continue;
-		/*
-		 * If the entry has been swapped out, we can stop looking.
-		 * No current caller is looking for DAX entries.
-		 */
-		if (xa_is_value(folio))
-			break;
-
-		if (!folio_try_get_rcu(folio))
-			goto retry;
-
-		if (unlikely(folio != xas_reload(&xas)))
-			goto put_page;
-
-again:
-		pages[ret] = folio_file_page(folio, xas.xa_index);
-		if (++ret == nr_pages)
-			break;
-		if (folio_more_pages(folio, xas.xa_index, ULONG_MAX)) {
-			xas.xa_index++;
-			folio_ref_inc(folio);
-			goto again;
-		}
-		continue;
-put_page:
-		folio_put(folio);
-retry:
-		xas_reset(&xas);
-	}
-	rcu_read_unlock();
-	return ret;
-}
-EXPORT_SYMBOL(find_get_pages_contig);
-
 /**
  * find_get_pages_range_tag - Find and return head pages matching @tag.
  * @mapping:	the address_space to search
-- 
2.36.1

Re: [PATCH v3 5/7] nilfs2: Convert nilfs_find_uncommited_extent() to use filemap_get_folios_contig()

[Ryusuke Konishi]

On Wed, Aug 24, 2022 at 9:43 AM Vishal Moola (Oracle)  wrote:
>
> Converted function to use folios throughout. This is in preparation for
> the removal of find_get_pages_contig(). Now also supports large folios.
>
> Also cleaned up an unnecessary if statement - pvec.pages[0]->index > index
> will always evaluate to false, and filemap_get_folios_contig() returns 0 if
> there is no folio found at index.
>
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> ---
>  fs/nilfs2/page.c | 45 ++++++++++++++++++---------------------------
>  1 file changed, 18 insertions(+), 27 deletions(-)

Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>

Looks good, thank you!


Ryusuke Konishi