Commit 2943fdbc authored by Ritesh Harjani's avatar Ritesh Harjani Committed by Theodore Ts'o
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ext4: Refactor mpage_map_and_submit_buffers function 



This patch refactors mpage_map_and_submit_buffers to take
out the page buffers processing, as a separate function.
This will be required to add support for blocksize < pagesize
for dioread_nolock feature.

No functionality change in this patch.

Signed-off-by: default avatarRitesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20191016073711.4141-4-riteshh@linux.ibm.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent a00713ea

fs/ext4/inode.c

+83 −42
Original line number Diff line number Diff line
@@ -2340,6 +2340,75 @@ static int mpage_process_page_bufs(struct mpage_da_data *mpd, 
	return lblk < blocks;

}



/*

 * mpage_process_page - update page buffers corresponding to changed extent and

 *		       may submit fully mapped page for IO

 *

 * @mpd		- description of extent to map, on return next extent to map

 * @m_lblk	- logical block mapping.

 * @m_pblk	- corresponding physical mapping.

 * @map_bh	- determines on return whether this page requires any further

 *		  mapping or not.

 * Scan given page buffers corresponding to changed extent and update buffer

 * state according to new extent state.

 * We map delalloc buffers to their physical location, clear unwritten bits.

 * If the given page is not fully mapped, we update @map to the next extent in

 * the given page that needs mapping & return @map_bh as true.

 */

static int mpage_process_page(struct mpage_da_data *mpd, struct page *page,

			      ext4_lblk_t *m_lblk, ext4_fsblk_t *m_pblk,

			      bool *map_bh)

{

	struct buffer_head *head, *bh;

	ext4_io_end_t *io_end = mpd->io_submit.io_end;

	ext4_lblk_t lblk = *m_lblk;

	ext4_fsblk_t pblock = *m_pblk;

	int err = 0;



	bh = head = page_buffers(page);

	do {

		if (lblk < mpd->map.m_lblk)

			continue;

		if (lblk >= mpd->map.m_lblk + mpd->map.m_len) {

			/*

			 * Buffer after end of mapped extent.

			 * Find next buffer in the page to map.

			 */

			mpd->map.m_len = 0;

			mpd->map.m_flags = 0;



			/*

			 * FIXME: If dioread_nolock supports

			 * blocksize < pagesize, we need to make

			 * sure we add size mapped so far to

			 * io_end->size as the following call

			 * can submit the page for IO.

			 */

			err = mpage_process_page_bufs(mpd, head, bh, lblk);

			if (err > 0)

				err = 0;

			*map_bh = true;

			goto out;

		}

		if (buffer_delay(bh)) {

			clear_buffer_delay(bh);

			bh->b_blocknr = pblock++;

		}

		clear_buffer_unwritten(bh);

	} while (lblk++, (bh = bh->b_this_page) != head);

	/*

	 * FIXME: This is going to break if dioread_nolock

	 * supports blocksize < pagesize as we will try to

	 * convert potentially unmapped parts of inode.

	 */

	io_end->size += PAGE_SIZE;

	*map_bh = false;

out:

	*m_lblk = lblk;

	*m_pblk = pblock;

	return err;

}



/*

 * mpage_map_buffers - update buffers corresponding to changed extent and

 *		       submit fully mapped pages for IO
@@ -2359,12 +2428,12 @@ static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd) 
	struct pagevec pvec;

	int nr_pages, i;

	struct inode *inode = mpd->inode;

	struct buffer_head *head, *bh;

	int bpp_bits = PAGE_SHIFT - inode->i_blkbits;

	pgoff_t start, end;

	ext4_lblk_t lblk;

	sector_t pblock;

	ext4_fsblk_t pblock;

	int err;

	bool map_bh = false;



	start = mpd->map.m_lblk >> bpp_bits;

	end = (mpd->map.m_lblk + mpd->map.m_len - 1) >> bpp_bits;
@@ -2380,50 +2449,19 @@ static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd) 
		for (i = 0; i < nr_pages; i++) {

			struct page *page = pvec.pages[i];



			bh = head = page_buffers(page);

			do {

				if (lblk < mpd->map.m_lblk)

					continue;

				if (lblk >= mpd->map.m_lblk + mpd->map.m_len) {

					/*

					 * Buffer after end of mapped extent.

					 * Find next buffer in the page to map.

					 */

					mpd->map.m_len = 0;

					mpd->map.m_flags = 0;

					/*

					 * FIXME: If dioread_nolock supports

					 * blocksize < pagesize, we need to make

					 * sure we add size mapped so far to

					 * io_end->size as the following call

					 * can submit the page for IO.

					 */

					err = mpage_process_page_bufs(mpd, head,

								      bh, lblk);

					pagevec_release(&pvec);

					if (err > 0)

						err = 0;

					return err;

				}

				if (buffer_delay(bh)) {

					clear_buffer_delay(bh);

					bh->b_blocknr = pblock++;

				}

				clear_buffer_unwritten(bh);

			} while (lblk++, (bh = bh->b_this_page) != head);



			err = mpage_process_page(mpd, page, &lblk, &pblock,

						 &map_bh);

			/*

			 * FIXME: This is going to break if dioread_nolock

			 * supports blocksize < pagesize as we will try to

			 * convert potentially unmapped parts of inode.

			 * If map_bh is true, means page may require further bh

			 * mapping, or maybe the page was submitted for IO.

			 * So we return to call further extent mapping.

			 */

			mpd->io_submit.io_end->size += PAGE_SIZE;

			if (err < 0 || map_bh == true)

				goto out;

			/* Page fully mapped - let IO run! */

			err = mpage_submit_page(mpd, page);

			if (err < 0) {

				pagevec_release(&pvec);

				return err;

			}

			if (err < 0)

				goto out;

		}

		pagevec_release(&pvec);

	}
@@ -2431,6 +2469,9 @@ static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd) 
	mpd->map.m_len = 0;

	mpd->map.m_flags = 0;

	return 0;

out:

	pagevec_release(&pvec);

	return err;

}



static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)

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