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Message-Id: <20191016073711.4141-4-riteshh@linux.ibm.com>
Date: Wed, 16 Oct 2019 13:07:09 +0530
From: Ritesh Harjani <riteshh@...ux.ibm.com>
To: tytso@....edu, jack@...e.cz, linux-ext4@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org, mbobrowski@...browski.org,
riteshh@...ux.ibm.com
Subject: [RFC 3/5] 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: Ritesh Harjani <riteshh@...ux.ibm.com>
---
fs/ext4/inode.c | 125 ++++++++++++++++++++++++++++++++----------------
1 file changed, 83 insertions(+), 42 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 123e3dee7733..3204a7d35581 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -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)
--
2.21.0
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