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@@ -36,6 +36,7 @@
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#include <linux/dcache.h>
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#include <linux/falloc.h>
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+#include <linux/pagevec.h>
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static const struct vm_operations_struct xfs_file_vm_ops;
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@@ -959,17 +960,232 @@ xfs_vm_page_mkwrite(
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return block_page_mkwrite(vma, vmf, xfs_get_blocks);
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}
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+/*
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+ * This type is designed to indicate the type of offset we would like
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+ * to search from page cache for either xfs_seek_data() or xfs_seek_hole().
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+ */
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+enum {
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+ HOLE_OFF = 0,
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+ DATA_OFF,
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+};
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+
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+/*
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+ * Lookup the desired type of offset from the given page.
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+ *
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+ * On success, return true and the offset argument will point to the
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+ * start of the region that was found. Otherwise this function will
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+ * return false and keep the offset argument unchanged.
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+ */
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+STATIC bool
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+xfs_lookup_buffer_offset(
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+ struct page *page,
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+ loff_t *offset,
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+ unsigned int type)
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+{
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+ loff_t lastoff = page_offset(page);
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+ bool found = false;
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+ struct buffer_head *bh, *head;
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+
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+ bh = head = page_buffers(page);
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+ do {
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+ /*
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+ * Unwritten extents that have data in the page
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+ * cache covering them can be identified by the
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+ * BH_Unwritten state flag. Pages with multiple
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+ * buffers might have a mix of holes, data and
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+ * unwritten extents - any buffer with valid
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+ * data in it should have BH_Uptodate flag set
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+ * on it.
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+ */
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+ if (buffer_unwritten(bh) ||
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+ buffer_uptodate(bh)) {
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+ if (type == DATA_OFF)
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+ found = true;
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+ } else {
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+ if (type == HOLE_OFF)
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+ found = true;
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+ }
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+
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+ if (found) {
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+ *offset = lastoff;
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+ break;
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+ }
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+ lastoff += bh->b_size;
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+ } while ((bh = bh->b_this_page) != head);
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+
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+ return found;
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+}
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+
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+/*
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+ * This routine is called to find out and return a data or hole offset
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+ * from the page cache for unwritten extents according to the desired
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+ * type for xfs_seek_data() or xfs_seek_hole().
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+ *
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+ * The argument offset is used to tell where we start to search from the
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+ * page cache. Map is used to figure out the end points of the range to
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+ * lookup pages.
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+ *
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+ * Return true if the desired type of offset was found, and the argument
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+ * offset is filled with that address. Otherwise, return false and keep
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+ * offset unchanged.
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+ */
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+STATIC bool
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+xfs_find_get_desired_pgoff(
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+ struct inode *inode,
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+ struct xfs_bmbt_irec *map,
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+ unsigned int type,
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+ loff_t *offset)
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+{
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+ struct xfs_inode *ip = XFS_I(inode);
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+ struct xfs_mount *mp = ip->i_mount;
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+ struct pagevec pvec;
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+ pgoff_t index;
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+ pgoff_t end;
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+ loff_t endoff;
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+ loff_t startoff = *offset;
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+ loff_t lastoff = startoff;
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+ bool found = false;
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+
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+ pagevec_init(&pvec, 0);
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+
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+ index = startoff >> PAGE_CACHE_SHIFT;
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+ endoff = XFS_FSB_TO_B(mp, map->br_startoff + map->br_blockcount);
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+ end = endoff >> PAGE_CACHE_SHIFT;
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+ do {
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+ int want;
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+ unsigned nr_pages;
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+ unsigned int i;
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+
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+ want = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
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+ nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
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+ want);
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+ /*
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+ * No page mapped into given range. If we are searching holes
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+ * and if this is the first time we got into the loop, it means
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+ * that the given offset is landed in a hole, return it.
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+ *
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+ * If we have already stepped through some block buffers to find
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+ * holes but they all contains data. In this case, the last
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+ * offset is already updated and pointed to the end of the last
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+ * mapped page, if it does not reach the endpoint to search,
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+ * that means there should be a hole between them.
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+ */
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+ if (nr_pages == 0) {
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+ /* Data search found nothing */
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+ if (type == DATA_OFF)
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+ break;
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+
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+ ASSERT(type == HOLE_OFF);
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+ if (lastoff == startoff || lastoff < endoff) {
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+ found = true;
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+ *offset = lastoff;
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+ }
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+ break;
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+ }
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+
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+ /*
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+ * At lease we found one page. If this is the first time we
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+ * step into the loop, and if the first page index offset is
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+ * greater than the given search offset, a hole was found.
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+ */
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+ if (type == HOLE_OFF && lastoff == startoff &&
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+ lastoff < page_offset(pvec.pages[0])) {
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+ found = true;
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+ break;
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+ }
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+
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+ for (i = 0; i < nr_pages; i++) {
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+ struct page *page = pvec.pages[i];
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+ loff_t b_offset;
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+
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+ /*
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+ * At this point, the page may be truncated or
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+ * invalidated (changing page->mapping to NULL),
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+ * or even swizzled back from swapper_space to tmpfs
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+ * file mapping. However, page->index will not change
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+ * because we have a reference on the page.
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+ *
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+ * Searching done if the page index is out of range.
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+ * If the current offset is not reaches the end of
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+ * the specified search range, there should be a hole
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+ * between them.
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+ */
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+ if (page->index > end) {
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+ if (type == HOLE_OFF && lastoff < endoff) {
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+ *offset = lastoff;
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+ found = true;
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+ }
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+ goto out;
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+ }
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+
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+ lock_page(page);
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+ /*
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+ * Page truncated or invalidated(page->mapping == NULL).
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+ * We can freely skip it and proceed to check the next
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+ * page.
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+ */
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+ if (unlikely(page->mapping != inode->i_mapping)) {
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+ unlock_page(page);
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+ continue;
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+ }
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+
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+ if (!page_has_buffers(page)) {
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+ unlock_page(page);
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+ continue;
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+ }
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+
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+ found = xfs_lookup_buffer_offset(page, &b_offset, type);
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+ if (found) {
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+ /*
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+ * The found offset may be less than the start
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+ * point to search if this is the first time to
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+ * come here.
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+ */
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+ *offset = max_t(loff_t, startoff, b_offset);
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+ unlock_page(page);
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+ goto out;
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+ }
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+
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+ /*
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+ * We either searching data but nothing was found, or
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+ * searching hole but found a data buffer. In either
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+ * case, probably the next page contains the desired
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+ * things, update the last offset to it so.
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+ */
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+ lastoff = page_offset(page) + PAGE_SIZE;
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+ unlock_page(page);
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+ }
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+
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+ /*
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+ * The number of returned pages less than our desired, search
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+ * done. In this case, nothing was found for searching data,
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+ * but we found a hole behind the last offset.
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+ */
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+ if (nr_pages < want) {
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+ if (type == HOLE_OFF) {
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+ *offset = lastoff;
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+ found = true;
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+ }
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+ break;
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+ }
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+
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+ index = pvec.pages[i - 1]->index + 1;
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+ pagevec_release(&pvec);
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+ } while (index <= end);
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+
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+out:
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+ pagevec_release(&pvec);
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+ return found;
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+}
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+
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STATIC loff_t
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xfs_seek_data(
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struct file *file,
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- loff_t start,
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- u32 type)
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+ loff_t start)
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{
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struct inode *inode = file->f_mapping->host;
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struct xfs_inode *ip = XFS_I(inode);
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struct xfs_mount *mp = ip->i_mount;
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- struct xfs_bmbt_irec map[2];
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- int nmap = 2;
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loff_t uninitialized_var(offset);
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xfs_fsize_t isize;
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xfs_fileoff_t fsbno;
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@@ -985,36 +1201,74 @@ xfs_seek_data(
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goto out_unlock;
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}
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- fsbno = XFS_B_TO_FSBT(mp, start);
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-
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/*
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* Try to read extents from the first block indicated
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* by fsbno to the end block of the file.
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*/
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+ fsbno = XFS_B_TO_FSBT(mp, start);
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end = XFS_B_TO_FSB(mp, isize);
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+ for (;;) {
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+ struct xfs_bmbt_irec map[2];
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+ int nmap = 2;
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+ unsigned int i;
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- error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
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- XFS_BMAPI_ENTIRE);
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- if (error)
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- goto out_unlock;
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+ error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
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+ XFS_BMAPI_ENTIRE);
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+ if (error)
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+ goto out_unlock;
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- /*
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- * Treat unwritten extent as data extent since it might
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- * contains dirty data in page cache.
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- */
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- if (map[0].br_startblock != HOLESTARTBLOCK) {
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- offset = max_t(loff_t, start,
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- XFS_FSB_TO_B(mp, map[0].br_startoff));
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- } else {
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+ /* No extents at given offset, must be beyond EOF */
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+ if (nmap == 0) {
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+ error = ENXIO;
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+ goto out_unlock;
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+ }
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+
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+ for (i = 0; i < nmap; i++) {
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+ offset = max_t(loff_t, start,
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+ XFS_FSB_TO_B(mp, map[i].br_startoff));
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+
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+ /* Landed in a data extent */
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+ if (map[i].br_startblock == DELAYSTARTBLOCK ||
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+ (map[i].br_state == XFS_EXT_NORM &&
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+ !isnullstartblock(map[i].br_startblock)))
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+ goto out;
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+
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+ /*
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+ * Landed in an unwritten extent, try to search data
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+ * from page cache.
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+ */
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+ if (map[i].br_state == XFS_EXT_UNWRITTEN) {
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+ if (xfs_find_get_desired_pgoff(inode, &map[i],
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+ DATA_OFF, &offset))
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+ goto out;
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+ }
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+ }
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+
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+ /*
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+ * map[0] is hole or its an unwritten extent but
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+ * without data in page cache. Probably means that
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+ * we are reading after EOF if nothing in map[1].
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+ */
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if (nmap == 1) {
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error = ENXIO;
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goto out_unlock;
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}
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- offset = max_t(loff_t, start,
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- XFS_FSB_TO_B(mp, map[1].br_startoff));
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+ ASSERT(i > 1);
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+
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+ /*
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+ * Nothing was found, proceed to the next round of search
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+ * if reading offset not beyond or hit EOF.
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+ */
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+ fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
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+ start = XFS_FSB_TO_B(mp, fsbno);
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+ if (start >= isize) {
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+ error = ENXIO;
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+ goto out_unlock;
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+ }
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}
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+out:
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if (offset != file->f_pos)
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file->f_pos = offset;
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@@ -1029,16 +1283,15 @@ out_unlock:
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STATIC loff_t
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xfs_seek_hole(
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struct file *file,
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- loff_t start,
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- u32 type)
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+ loff_t start)
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{
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struct inode *inode = file->f_mapping->host;
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struct xfs_inode *ip = XFS_I(inode);
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struct xfs_mount *mp = ip->i_mount;
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loff_t uninitialized_var(offset);
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- loff_t holeoff;
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xfs_fsize_t isize;
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xfs_fileoff_t fsbno;
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+ xfs_filblks_t end;
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uint lock;
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int error;
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@@ -1054,21 +1307,77 @@ xfs_seek_hole(
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}
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fsbno = XFS_B_TO_FSBT(mp, start);
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- error = xfs_bmap_first_unused(NULL, ip, 1, &fsbno, XFS_DATA_FORK);
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- if (error)
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- goto out_unlock;
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+ end = XFS_B_TO_FSB(mp, isize);
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+
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+ for (;;) {
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+ struct xfs_bmbt_irec map[2];
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+ int nmap = 2;
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+ unsigned int i;
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+
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+ error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
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+ XFS_BMAPI_ENTIRE);
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+ if (error)
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+ goto out_unlock;
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+
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+ /* No extents at given offset, must be beyond EOF */
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+ if (nmap == 0) {
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+ error = ENXIO;
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+ goto out_unlock;
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+ }
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+
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+ for (i = 0; i < nmap; i++) {
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+ offset = max_t(loff_t, start,
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+ XFS_FSB_TO_B(mp, map[i].br_startoff));
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+
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+ /* Landed in a hole */
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+ if (map[i].br_startblock == HOLESTARTBLOCK)
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+ goto out;
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+
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+ /*
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+ * Landed in an unwritten extent, try to search hole
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+ * from page cache.
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+ */
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+ if (map[i].br_state == XFS_EXT_UNWRITTEN) {
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+ if (xfs_find_get_desired_pgoff(inode, &map[i],
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+ HOLE_OFF, &offset))
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+ goto out;
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+ }
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+ }
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+
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+ /*
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+ * map[0] contains data or its unwritten but contains
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+ * data in page cache, probably means that we are
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+ * reading after EOF. We should fix offset to point
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+ * to the end of the file(i.e., there is an implicit
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+ * hole at the end of any file).
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+ */
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+ if (nmap == 1) {
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+ offset = isize;
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+ break;
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+ }
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+
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+ ASSERT(i > 1);
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- holeoff = XFS_FSB_TO_B(mp, fsbno);
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- if (holeoff <= start)
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- offset = start;
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- else {
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/*
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- * xfs_bmap_first_unused() could return a value bigger than
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- * isize if there are no more holes past the supplied offset.
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+ * Both mappings contains data, proceed to the next round of
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+ * search if the current reading offset not beyond or hit EOF.
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*/
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- offset = min_t(loff_t, holeoff, isize);
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+ fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
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+ start = XFS_FSB_TO_B(mp, fsbno);
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|
+ if (start >= isize) {
|
|
|
+ offset = isize;
|
|
|
+ break;
|
|
|
+ }
|
|
|
}
|
|
|
|
|
|
+out:
|
|
|
+ /*
|
|
|
+ * At this point, we must have found a hole. However, the returned
|
|
|
+ * offset may be bigger than the file size as it may be aligned to
|
|
|
+ * page boundary for unwritten extents, we need to deal with this
|
|
|
+ * situation in particular.
|
|
|
+ */
|
|
|
+ offset = min_t(loff_t, offset, isize);
|
|
|
if (offset != file->f_pos)
|
|
|
file->f_pos = offset;
|
|
|
|
|
@@ -1092,9 +1401,9 @@ xfs_file_llseek(
|
|
|
case SEEK_SET:
|
|
|
return generic_file_llseek(file, offset, origin);
|
|
|
case SEEK_DATA:
|
|
|
- return xfs_seek_data(file, offset, origin);
|
|
|
+ return xfs_seek_data(file, offset);
|
|
|
case SEEK_HOLE:
|
|
|
- return xfs_seek_hole(file, offset, origin);
|
|
|
+ return xfs_seek_hole(file, offset);
|
|
|
default:
|
|
|
return -EINVAL;
|
|
|
}
|