fs: use ->is_partially_uptodate in page_cache_seek_hole_data

This way the implementation doesn't depend on buffer_head internals.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/iomap.c b/fs/iomap.c
index 2a20d50..206539d 100644 (file)
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -595,34 +595,53 @@ EXPORT_SYMBOL_GPL(iomap_fiemap);
 
 /*
  * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.
- *
- * Returns the offset within the file on success, and -ENOENT otherwise.
+ * Returns true if found and updates @lastoff to the offset in file.
  */
-static loff_t
-page_seek_hole_data(struct page *page, loff_t lastoff, int whence)
+static bool
+page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,
+               int whence)
 {
-       loff_t offset = page_offset(page);
-       struct buffer_head *bh, *head;
+       const struct address_space_operations *ops = inode->i_mapping->a_ops;
+       unsigned int bsize = i_blocksize(inode), off;
        bool seek_data = whence == SEEK_DATA;
+       loff_t poff = page_offset(page);
 
-       if (lastoff < offset)
-               lastoff = offset;
-
-       bh = head = page_buffers(page);
-       do {
-               offset += bh->b_size;
-               if (lastoff >= offset)
-                       continue;
+       if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE))
+               return false;
 
+       if (*lastoff < poff) {
                /*
-                * Any buffer with valid data in it should have BH_Uptodate set.
+                * Last offset smaller than the start of the page means we found
+                * a hole:
                 */
-               if (buffer_uptodate(bh) == seek_data)
-                       return lastoff;
+               if (whence == SEEK_HOLE)
+                       return true;
+               *lastoff = poff;
+       }
 
-               lastoff = offset;
-       } while ((bh = bh->b_this_page) != head);
-       return -ENOENT;
+       /*
+        * Just check the page unless we can and should check block ranges:
+        */
+       if (bsize == PAGE_SIZE || !ops->is_partially_uptodate)
+               return PageUptodate(page) == seek_data;
+
+       lock_page(page);
+       if (unlikely(page->mapping != inode->i_mapping))
+               goto out_unlock_not_found;
+
+       for (off = 0; off < PAGE_SIZE; off += bsize) {
+               if ((*lastoff & ~PAGE_MASK) >= off + bsize)
+                       continue;
+               if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {
+                       unlock_page(page);
+                       return true;
+               }
+               *lastoff = poff + off + bsize;
+       }
+
+out_unlock_not_found:
+       unlock_page(page);
+       return false;
 }
 
 /*
@@ -659,30 +678,8 @@ page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
                for (i = 0; i < nr_pages; i++) {
                        struct page *page = pvec.pages[i];
 
-                       /*
-                        * 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 (whence == SEEK_HOLE &&
-                           lastoff < page_offset(page))
+                       if (page_seek_hole_data(inode, page, &lastoff, whence))
                                goto check_range;
-
-                       lock_page(page);
-                       if (likely(page->mapping == inode->i_mapping) &&
-                           page_has_buffers(page)) {
-                               lastoff = page_seek_hole_data(page, lastoff, whence);
-                               if (lastoff >= 0) {
-                                       unlock_page(page);
-                                       goto check_range;
-                               }
-                       }
-                       unlock_page(page);
                        lastoff = page_offset(page) + PAGE_SIZE;
                }
                pagevec_release(&pvec);