+ buffer-return-bool-from-grow_dev_folio.patch added to mm-unstable branch

+ buffer-return-bool-from-grow_dev_folio.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: buffer: return bool from grow_dev_folio()
has been added to the -mm mm-unstable branch.  Its filename is
     buffer-return-bool-from-grow_dev_folio.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/buffer-return-bool-from-grow_dev_folio.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: buffer: return bool from grow_dev_folio()
Date: Mon, 16 Oct 2023 21:10:48 +0100

Patch series "Finish the create_empty_buffers() transition", v2.

Pankaj recently added folio_create_empty_buffers() as the folio equivalent
to create_empty_buffers().  This patch set finishes the conversion by
first converting all remaining filesystems to call
folio_create_empty_buffers(), then renaming it back to
create_empty_buffers().  I took the opportunity to make a few
simplifications like making folio_create_empty_buffers() return the head
buffer and extracting get_nth_bh() from nilfs2.

A few of the patches in this series aren't directly related to
create_empty_buffers(), but I saw them while I was working on this and
thought they'd be easy enough to add to this series.  Compile-tested only,
other than ext4.


This patch (of 27):

Rename grow_dev_page() to grow_dev_folio() and make it return a bool. 
Document what that bool means; it's more subtle than it first appears. 
Also rename the 'failed' label to 'unlock' beacuse it's not exactly
'failed'.  It just hasn't succeeded.

Link: https://lkml.kernel.org/r/20231016201114.1928083-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20231016201114.1928083-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/buffer.c |   39 ++++++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 17 deletions(-)

--- a/fs/buffer.c~buffer-return-bool-from-grow_dev_folio
+++ a/fs/buffer.c
@@ -1024,24 +1024,26 @@ static sector_t folio_init_buffers(struc
 }
 
 /*
- * Create the page-cache page that contains the requested block.
+ * Create the page-cache folio that contains the requested block.
  *
  * This is used purely for blockdev mappings.
+ *
+ * Returns false if we have a 'permanent' failure.  Returns true if
+ * we succeeded, or the caller should retry.
  */
-static int
-grow_dev_page(struct block_device *bdev, sector_t block,
+static bool grow_dev_folio(struct block_device *bdev, sector_t block,
 	      pgoff_t index, int size, int sizebits, gfp_t gfp)
 {
 	struct inode *inode = bdev->bd_inode;
 	struct folio *folio;
 	struct buffer_head *bh;
 	sector_t end_block;
-	int ret = 0;
+	bool ret;
 
 	folio = __filemap_get_folio(inode->i_mapping, index,
 			FGP_LOCK | FGP_ACCESSED | FGP_CREAT, gfp);
 	if (IS_ERR(folio))
-		return PTR_ERR(folio);
+		return false;
 
 	bh = folio_buffers(folio);
 	if (bh) {
@@ -1050,14 +1052,17 @@ grow_dev_page(struct block_device *bdev,
 					(sector_t)index << sizebits, size);
 			goto done;
 		}
+
+		/* Caller should retry if this call fails */
+		ret = true;
 		if (!try_to_free_buffers(folio))
-			goto failed;
+			goto unlock;
 	}
 
-	ret = -ENOMEM;
+	ret = false;
 	bh = folio_alloc_buffers(folio, size, gfp | __GFP_ACCOUNT);
 	if (!bh)
-		goto failed;
+		goto unlock;
 
 	/*
 	 * Link the folio to the buffers and initialise them.  Take the
@@ -1070,19 +1075,19 @@ grow_dev_page(struct block_device *bdev,
 			(sector_t)index << sizebits, size);
 	spin_unlock(&inode->i_mapping->private_lock);
 done:
-	ret = (block < end_block) ? 1 : -ENXIO;
-failed:
+	ret = block < end_block;
+unlock:
 	folio_unlock(folio);
 	folio_put(folio);
 	return ret;
 }
 
 /*
- * Create buffers for the specified block device block's page.  If
- * that page was dirty, the buffers are set dirty also.
+ * Create buffers for the specified block device block's folio.  If
+ * that folio was dirty, the buffers are set dirty also.
  */
-static int
-grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp)
+static bool grow_buffers(struct block_device *bdev, sector_t block,
+		int size, gfp_t gfp)
 {
 	pgoff_t index;
 	int sizebits;
@@ -1099,11 +1104,11 @@ grow_buffers(struct block_device *bdev,
 			"device %pg\n",
 			__func__, (unsigned long long)block,
 			bdev);
-		return -EIO;
+		return false;
 	}
 
-	/* Create a page with the proper size buffers.. */
-	return grow_dev_page(bdev, block, index, size, sizebits, gfp);
+	/* Create a folio with the proper size buffers.. */
+	return grow_dev_folio(bdev, block, index, size, sizebits, gfp);
 }
 
 static struct buffer_head *
_

Patches currently in -mm which might be from willy@infradead.org are

mm-make-lock_folio_maybe_drop_mmap-vma-lock-aware.patch
mm-call-wp_page_copy-under-the-vma-lock.patch
mm-handle-shared-faults-under-the-vma-lock.patch
mm-handle-cow-faults-under-the-vma-lock.patch
mm-handle-read-faults-under-the-vma-lock.patch
mm-handle-write-faults-to-ro-pages-under-the-vma-lock.patch
iomap-hold-state_lock-over-call-to-ifs_set_range_uptodate.patch
iomap-protect-read_bytes_pending-with-the-state_lock.patch
mm-add-folio_end_read.patch
ext4-use-folio_end_read.patch
buffer-use-folio_end_read.patch
iomap-use-folio_end_read.patch
bitops-add-xor_unlock_is_negative_byte.patch
alpha-implement-xor_unlock_is_negative_byte.patch
m68k-implement-xor_unlock_is_negative_byte.patch
mips-implement-xor_unlock_is_negative_byte.patch
powerpc-implement-arch_xor_unlock_is_negative_byte-on-32-bit.patch
riscv-implement-xor_unlock_is_negative_byte.patch
s390-implement-arch_xor_unlock_is_negative_byte.patch
mm-delete-checks-for-xor_unlock_is_negative_byte.patch
mm-add-folio_xor_flags_has_waiters.patch
mm-make-__end_folio_writeback-return-void.patch
mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback.patch
filemap-remove-use-of-wait-bookmarks.patch
sched-remove-wait-bookmarks.patch
buffer-return-bool-from-grow_dev_folio.patch
buffer-make-folio_create_empty_buffers-return-a-buffer_head.patch
mpage-convert-map_buffer_to_folio-to-folio_create_empty_buffers.patch
ext4-convert-to-folio_create_empty_buffers.patch
buffer-add-get_nth_bh.patch
gfs2-convert-inode-unstuffing-to-use-a-folio.patch
gfs2-convert-gfs2_getbuf-to-folios.patch
gfs2-convert-gfs2_getjdatabuf-to-use-a-folio.patch
gfs2-convert-gfs2_write_buf_to_page-to-use-a-folio.patch
nilfs2-convert-nilfs_mdt_freeze_buffer-to-use-a-folio.patch
nilfs2-convert-nilfs_grab_buffer-to-use-a-folio.patch
nilfs2-convert-nilfs_copy_page-to-nilfs_copy_folio.patch
nilfs2-convert-nilfs_mdt_forget_block-to-use-a-folio.patch
nilfs2-convert-nilfs_mdt_get_frozen_buffer-to-use-a-folio.patch
nilfs2-remove-nilfs_page_get_nth_block.patch
nilfs2-convert-nilfs_lookup_dirty_data_buffers-to-use-folio_create_empty_buffers.patch
ntfs-convert-ntfs_read_block-to-use-a-folio.patch
ntfs-convert-ntfs_writepage-to-use-a-folio.patch
ntfs-convert-ntfs_prepare_pages_for_non_resident_write-to-folios.patch
ntfs3-convert-ntfs_zero_range-to-use-a-folio.patch
ocfs2-convert-ocfs2_map_page_blocks-to-use-a-folio.patch
reiserfs-convert-writepage-to-use-a-folio.patch
ufs-add-ufs_get_locked_folio-and-ufs_put_locked_folio.patch
ufs-use-ufs_get_locked_folio-in-ufs_alloc_lastblock.patch
ufs-convert-ufs_change_blocknr-to-use-folios.patch
ufs-remove-ufs_get_locked_page.patch
buffer-remove-folio_create_empty_buffers.patch

+ buffer-return-bool-from-grow_dev_folio.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: buffer: return bool from grow_dev_folio()
has been added to the -mm mm-unstable branch.  Its filename is
     buffer-return-bool-from-grow_dev_folio.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/buffer-return-bool-from-grow_dev_folio.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: buffer: return bool from grow_dev_folio()
Date: Thu, 9 Nov 2023 21:06:02 +0000

Patch series "More buffer_head cleanups", v2.

The first patch is a left-over from last cycle.  The rest fix "obvious"
block size > PAGE_SIZE problems.  I haven't tested with a large block size
setup (but I have done an ext4 xfstests run).


This patch (of 7):

Rename grow_dev_page() to grow_dev_folio() and make it return a bool. 
Document what that bool means; it's more subtle than it first appears. 
Also rename the 'failed' label to 'unlock' beacuse it's not exactly
'failed'.  It just hasn't succeeded.

Link: https://lkml.kernel.org/r/20231109210608.2252323-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/buffer.c |   50 +++++++++++++++++++++++++-------------------------
 1 file changed, 25 insertions(+), 25 deletions(-)

--- a/fs/buffer.c~buffer-return-bool-from-grow_dev_folio
+++ a/fs/buffer.c
@@ -1024,40 +1024,43 @@ static sector_t folio_init_buffers(struc
 }
 
 /*
- * Create the page-cache page that contains the requested block.
+ * Create the page-cache folio that contains the requested block.
  *
  * This is used purely for blockdev mappings.
+ *
+ * Returns false if we have a 'permanent' failure.  Returns true if
+ * we succeeded, or the caller should retry.
  */
-static int
-grow_dev_page(struct block_device *bdev, sector_t block,
-	      pgoff_t index, int size, int sizebits, gfp_t gfp)
+static bool grow_dev_folio(struct block_device *bdev, sector_t block,
+		pgoff_t index, unsigned size, int sizebits, gfp_t gfp)
 {
 	struct inode *inode = bdev->bd_inode;
 	struct folio *folio;
 	struct buffer_head *bh;
-	sector_t end_block;
-	int ret = 0;
+	sector_t end_block = 0;
 
 	folio = __filemap_get_folio(inode->i_mapping, index,
 			FGP_LOCK | FGP_ACCESSED | FGP_CREAT, gfp);
 	if (IS_ERR(folio))
-		return PTR_ERR(folio);
+		return false;
 
 	bh = folio_buffers(folio);
 	if (bh) {
 		if (bh->b_size == size) {
 			end_block = folio_init_buffers(folio, bdev,
 					(sector_t)index << sizebits, size);
-			goto done;
+			goto unlock;
 		}
+
+		/* Caller should retry if this call fails */
+		end_block = ~0ULL;
 		if (!try_to_free_buffers(folio))
-			goto failed;
+			goto unlock;
 	}
 
-	ret = -ENOMEM;
 	bh = folio_alloc_buffers(folio, size, gfp | __GFP_ACCOUNT);
 	if (!bh)
-		goto failed;
+		goto unlock;
 
 	/*
 	 * Link the folio to the buffers and initialise them.  Take the
@@ -1069,20 +1072,19 @@ grow_dev_page(struct block_device *bdev,
 	end_block = folio_init_buffers(folio, bdev,
 			(sector_t)index << sizebits, size);
 	spin_unlock(&inode->i_mapping->private_lock);
-done:
-	ret = (block < end_block) ? 1 : -ENXIO;
-failed:
+unlock:
 	folio_unlock(folio);
 	folio_put(folio);
-	return ret;
+	return block < end_block;
 }
 
 /*
- * Create buffers for the specified block device block's page.  If
- * that page was dirty, the buffers are set dirty also.
+ * Create buffers for the specified block device block's folio.  If
+ * that folio was dirty, the buffers are set dirty also.  Returns false
+ * if we've hit a permanent error.
  */
-static int
-grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp)
+static bool grow_buffers(struct block_device *bdev, sector_t block,
+		unsigned size, gfp_t gfp)
 {
 	pgoff_t index;
 	int sizebits;
@@ -1099,11 +1101,11 @@ grow_buffers(struct block_device *bdev,
 			"device %pg\n",
 			__func__, (unsigned long long)block,
 			bdev);
-		return -EIO;
+		return false;
 	}
 
-	/* Create a page with the proper size buffers.. */
-	return grow_dev_page(bdev, block, index, size, sizebits, gfp);
+	/* Create a folio with the proper size buffers */
+	return grow_dev_folio(bdev, block, index, size, sizebits, gfp);
 }
 
 static struct buffer_head *
@@ -1124,14 +1126,12 @@ __getblk_slow(struct block_device *bdev,
 
 	for (;;) {
 		struct buffer_head *bh;
-		int ret;
 
 		bh = __find_get_block(bdev, block, size);
 		if (bh)
 			return bh;
 
-		ret = grow_buffers(bdev, block, size, gfp);
-		if (ret < 0)
+		if (!grow_buffers(bdev, block, size, gfp))
 			return NULL;
 	}
 }
_

Patches currently in -mm which might be from willy@infradead.org are

mm-add-folio_zero_tail-and-use-it-in-ext4.patch
mm-add-folio_fill_tail-and-use-it-in-iomap.patch
gfs2-convert-stuffed_readpage-to-stuffed_read_folio.patch
mm-remove-test_set_page_writeback.patch
afs-do-not-test-the-return-value-of-folio_start_writeback.patch
smb-do-not-test-the-return-value-of-folio_start_writeback.patch
mm-return-void-from-folio_start_writeback-and-related-functions.patch
mm-make-mapping_evict_folio-the-preferred-way-to-evict-clean-folios.patch
mm-convert-__do_fault-to-use-a-folio.patch
mm-use-mapping_evict_folio-in-truncate_error_page.patch
mm-convert-soft_offline_in_use_page-to-use-a-folio.patch
mm-convert-isolate_page-to-mf_isolate_folio.patch
mm-remove-invalidate_inode_page.patch
buffer-return-bool-from-grow_dev_folio.patch
buffer-calculate-block-number-inside-folio_init_buffers.patch
buffer-fix-grow_buffers-for-block-size-page_size.patch
buffer-cast-block-to-loff_t-before-shifting-it.patch
buffer-fix-various-functions-for-block-size-page_size.patch
buffer-handle-large-folios-in-__block_write_begin_int.patch
buffer-fix-more-functions-for-block-size-page_size.patch