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Message-Id: <1498487118-6564-4-git-send-email-agruenba@redhat.com>
Date: Mon, 26 Jun 2017 16:25:16 +0200
From: Andreas Gruenbacher <agruenba@...hat.com>
To: linux-fsdevel@...r.kernel.org
Cc: Andreas Gruenbacher <agruenba@...hat.com>,
linux-xfs@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: [PATCH v3 3/5] xfs: Switch to page_cache_seek_hole_data
Fix SEEK_HOLE / SEEK_DATA when a page fits more than two filesystem
blocks (see the commit that introduces page_cache_seek_hole_data).
Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
---
fs/xfs/xfs_file.c | 197 +++---------------------------------------------------
1 file changed, 9 insertions(+), 188 deletions(-)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 86701a0..962dafd 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -981,191 +981,6 @@ xfs_file_readdir(
}
/*
- * This type is designed to indicate the type of offset we would like
- * to search from page cache for xfs_seek_hole_data().
- */
-enum {
- HOLE_OFF = 0,
- DATA_OFF,
-};
-
-/*
- * Lookup the desired type of offset from the given page.
- *
- * On success, return true and the offset argument will point to the
- * start of the region that was found. Otherwise this function will
- * return false and keep the offset argument unchanged.
- */
-STATIC bool
-xfs_lookup_buffer_offset(
- struct page *page,
- loff_t *offset,
- unsigned int type)
-{
- loff_t lastoff = page_offset(page);
- bool found = false;
- struct buffer_head *bh, *head;
-
- bh = head = page_buffers(page);
- do {
- /*
- * Unwritten extents that have data in the page
- * cache covering them can be identified by the
- * BH_Unwritten state flag. Pages with multiple
- * buffers might have a mix of holes, data and
- * unwritten extents - any buffer with valid
- * data in it should have BH_Uptodate flag set
- * on it.
- */
- if (buffer_unwritten(bh) ||
- buffer_uptodate(bh)) {
- if (type == DATA_OFF)
- found = true;
- } else {
- if (type == HOLE_OFF)
- found = true;
- }
-
- if (found) {
- *offset = lastoff;
- break;
- }
- lastoff += bh->b_size;
- } while ((bh = bh->b_this_page) != head);
-
- return found;
-}
-
-/*
- * This routine is called to find out and return a data or hole offset
- * from the page cache for unwritten extents according to the desired
- * type for xfs_seek_hole_data().
- *
- * The argument offset is used to tell where we start to search from the
- * page cache. Map is used to figure out the end points of the range to
- * lookup pages.
- *
- * Return true if the desired type of offset was found, and the argument
- * offset is filled with that address. Otherwise, return false and keep
- * offset unchanged.
- */
-STATIC bool
-xfs_find_get_desired_pgoff(
- struct inode *inode,
- struct xfs_bmbt_irec *map,
- unsigned int type,
- loff_t *offset)
-{
- struct xfs_inode *ip = XFS_I(inode);
- struct xfs_mount *mp = ip->i_mount;
- struct pagevec pvec;
- pgoff_t index;
- pgoff_t end;
- loff_t endoff;
- loff_t startoff = *offset;
- loff_t lastoff = startoff;
- bool found = false;
-
- pagevec_init(&pvec, 0);
-
- index = startoff >> PAGE_SHIFT;
- endoff = XFS_FSB_TO_B(mp, map->br_startoff + map->br_blockcount);
- end = (endoff - 1) >> PAGE_SHIFT;
- do {
- int want;
- unsigned nr_pages;
- unsigned int i;
-
- want = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1;
- nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
- want);
- if (nr_pages == 0)
- break;
-
- for (i = 0; i < nr_pages; i++) {
- struct page *page = pvec.pages[i];
- loff_t b_offset;
-
- /*
- * At this point, the page may be truncated or
- * invalidated (changing page->mapping to NULL),
- * or even swizzled back from swapper_space to tmpfs
- * file mapping. However, page->index will not change
- * because we have a reference on the page.
- *
- * If current page offset is beyond where we've ended,
- * we've found a hole.
- */
- if (type == HOLE_OFF && lastoff < endoff &&
- lastoff < page_offset(pvec.pages[i])) {
- found = true;
- *offset = lastoff;
- goto out;
- }
- /* Searching done if the page index is out of range. */
- if (page->index > end)
- goto out;
-
- lock_page(page);
- /*
- * Page truncated or invalidated(page->mapping == NULL).
- * We can freely skip it and proceed to check the next
- * page.
- */
- if (unlikely(page->mapping != inode->i_mapping)) {
- unlock_page(page);
- continue;
- }
-
- if (!page_has_buffers(page)) {
- unlock_page(page);
- continue;
- }
-
- found = xfs_lookup_buffer_offset(page, &b_offset, type);
- if (found) {
- /*
- * The found offset may be less than the start
- * point to search if this is the first time to
- * come here.
- */
- *offset = max_t(loff_t, startoff, b_offset);
- unlock_page(page);
- goto out;
- }
-
- /*
- * We either searching data but nothing was found, or
- * searching hole but found a data buffer. In either
- * case, probably the next page contains the desired
- * things, update the last offset to it so.
- */
- lastoff = page_offset(page) + PAGE_SIZE;
- unlock_page(page);
- }
-
- /*
- * The number of returned pages less than our desired, search
- * done.
- */
- if (nr_pages < want)
- break;
-
- index = pvec.pages[i - 1]->index + 1;
- pagevec_release(&pvec);
- } while (index <= end);
-
- /* No page at lastoff and we are not done - we found a hole. */
- if (type == HOLE_OFF && lastoff < endoff) {
- *offset = lastoff;
- found = true;
- }
-out:
- pagevec_release(&pvec);
- return found;
-}
-
-/*
* caller must lock inode with xfs_ilock_data_map_shared,
* can we craft an appropriate ASSERT?
*
@@ -1236,10 +1051,16 @@ __xfs_seek_hole_data(
* for hole or data from page cache.
*/
if (map[i].br_state == XFS_EXT_UNWRITTEN) {
- if (xfs_find_get_desired_pgoff(inode, &map[i],
- whence == SEEK_HOLE ? HOLE_OFF : DATA_OFF,
- &offset))
+ xfs_fileoff_t endoff = map[i].br_startoff +
+ map[i].br_blockcount;
+ loff_t length = XFS_FSB_TO_B(mp, endoff) - offset;
+ loff_t ret;
+
+ ret = page_cache_seek_hole_data(inode, offset, length, whence);
+ if (ret >= 0) {
+ offset = ret;
goto out;
+ }
}
}
--
2.7.5
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