Merge tag 'dma-mapping-5.13' of git://git.infradead.org/users/hch/dma-mapping

[linux-2.6-microblaze.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index 151090f..5be57ba 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -635,6 +635,49 @@ static bool mapping_needs_writeback(struct address_space *mapping)
        return mapping->nrpages;
 }
 
+/**
+ * filemap_range_needs_writeback - check if range potentially needs writeback
+ * @mapping:           address space within which to check
+ * @start_byte:        offset in bytes where the range starts
+ * @end_byte:          offset in bytes where the range ends (inclusive)
+ *
+ * Find at least one page in the range supplied, usually used to check if
+ * direct writing in this range will trigger a writeback. Used by O_DIRECT
+ * read/write with IOCB_NOWAIT, to see if the caller needs to do
+ * filemap_write_and_wait_range() before proceeding.
+ *
+ * Return: %true if the caller should do filemap_write_and_wait_range() before
+ * doing O_DIRECT to a page in this range, %false otherwise.
+ */
+bool filemap_range_needs_writeback(struct address_space *mapping,
+                                  loff_t start_byte, loff_t end_byte)
+{
+       XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
+       pgoff_t max = end_byte >> PAGE_SHIFT;
+       struct page *page;
+
+       if (!mapping_needs_writeback(mapping))
+               return false;
+       if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
+           !mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK))
+               return false;
+       if (end_byte < start_byte)
+               return false;
+
+       rcu_read_lock();
+       xas_for_each(&xas, page, max) {
+               if (xas_retry(&xas, page))
+                       continue;
+               if (xa_is_value(page))
+                       continue;
+               if (PageDirty(page) || PageLocked(page) || PageWriteback(page))
+                       break;
+       }
+       rcu_read_unlock();
+       return page != NULL;
+}
+EXPORT_SYMBOL_GPL(filemap_range_needs_writeback);
+
 /**
  * filemap_write_and_wait_range - write out & wait on a file range
  * @mapping:   the address_space for the pages
@@ -1724,7 +1767,7 @@ EXPORT_SYMBOL(page_cache_prev_miss);
  * @mapping: the address_space to search
  * @index: The page cache index.
  *
- * Looks up the page cache slot at @mapping & @offset.  If there is a
+ * Looks up the page cache slot at @mapping & @index.  If there is a
  * page cache page, the head page is returned with an increased refcount.
  *
  * If the slot holds a shadow entry of a previously evicted page, or a
@@ -2305,8 +2348,6 @@ static int filemap_read_page(struct file *file, struct address_space *mapping,
                return error;
        if (PageUptodate(page))
                return 0;
-       if (!page->mapping)     /* page truncated */
-               return AOP_TRUNCATED_PAGE;
        shrink_readahead_size_eio(&file->f_ra);
        return -EIO;
 }
@@ -2638,8 +2679,8 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 
                size = i_size_read(inode);
                if (iocb->ki_flags & IOCB_NOWAIT) {
-                       if (filemap_range_has_page(mapping, iocb->ki_pos,
-                                                  iocb->ki_pos + count - 1))
+                       if (filemap_range_needs_writeback(mapping, iocb->ki_pos,
+                                               iocb->ki_pos + count - 1))
                                return -EAGAIN;
                } else {
                        retval = filemap_write_and_wait_range(mapping,
@@ -2937,7 +2978,6 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
        struct file *file = vmf->vma->vm_file;
        struct file *fpin = NULL;
        struct address_space *mapping = file->f_mapping;
-       struct file_ra_state *ra = &file->f_ra;
        struct inode *inode = mapping->host;
        pgoff_t offset = vmf->pgoff;
        pgoff_t max_off;
@@ -3024,14 +3064,8 @@ page_not_uptodate:
         * because there really aren't any performance issues here
         * and we need to check for errors.
         */
-       ClearPageError(page);
        fpin = maybe_unlock_mmap_for_io(vmf, fpin);
-       error = mapping->a_ops->readpage(file, page);
-       if (!error) {
-               wait_on_page_locked(page);
-               if (!PageUptodate(page))
-                       error = -EIO;
-       }
+       error = filemap_read_page(file, mapping, page);
        if (fpin)
                goto out_retry;
        put_page(page);
@@ -3039,7 +3073,6 @@ page_not_uptodate:
        if (!error || error == AOP_TRUNCATED_PAGE)
                goto retry_find;
 
-       shrink_readahead_size_eio(ra);
        return VM_FAULT_SIGBUS;
 
 out_retry: