dax: move writeback calls into the filesystems

Previously calls to dax_writeback_mapping_range() for all DAX filesystems
(ext2, ext4 & xfs) were centralized in filemap_write_and_wait_range().

dax_writeback_mapping_range() needs a struct block_device, and it used
to get that from inode->i_sb->s_bdev.  This is correct for normal inodes
mounted on ext2, ext4 and XFS filesystems, but is incorrect for DAX raw
block devices and for XFS real-time files.

Instead, call dax_writeback_mapping_range() directly from the filesystem
->writepages function so that it can supply us with a valid block
device.  This also fixes DAX code to properly flush caches in response
to sync(2).

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 31c6d10..826b164 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1697,13 +1697,24 @@ static int blkdev_releasepage(struct page *page, gfp_t wait)
        return try_to_free_buffers(page);
 }
 
+static int blkdev_writepages(struct address_space *mapping,
+                            struct writeback_control *wbc)
+{
+       if (dax_mapping(mapping)) {
+               struct block_device *bdev = I_BDEV(mapping->host);
+
+               return dax_writeback_mapping_range(mapping, bdev, wbc);
+       }
+       return generic_writepages(mapping, wbc);
+}
+
 static const struct address_space_operations def_blk_aops = {
        .readpage       = blkdev_readpage,
        .readpages      = blkdev_readpages,
        .writepage      = blkdev_writepage,
        .write_begin    = blkdev_write_begin,
        .write_end      = blkdev_write_end,
-       .writepages     = generic_writepages,
+       .writepages     = blkdev_writepages,
        .releasepage    = blkdev_releasepage,
        .direct_IO      = blkdev_direct_IO,
        .is_dirty_writeback = buffer_check_dirty_writeback,

diff --git a/fs/dax.c b/fs/dax.c
index 9a173dd..7111724 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -484,11 +484,10 @@ static int dax_writeback_one(struct block_device *bdev,
  * end]. This is required by data integrity operations to ensure file data is
  * on persistent storage prior to completion of the operation.
  */
-int dax_writeback_mapping_range(struct address_space *mapping, loff_t start,
-               loff_t end)
+int dax_writeback_mapping_range(struct address_space *mapping,
+               struct block_device *bdev, struct writeback_control *wbc)
 {
        struct inode *inode = mapping->host;
-       struct block_device *bdev = inode->i_sb->s_bdev;
        pgoff_t start_index, end_index, pmd_index;
        pgoff_t indices[PAGEVEC_SIZE];
        struct pagevec pvec;
@@ -499,8 +498,11 @@ int dax_writeback_mapping_range(struct address_space *mapping, loff_t start,
        if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT))
                return -EIO;
 
-       start_index = start >> PAGE_CACHE_SHIFT;
-       end_index = end >> PAGE_CACHE_SHIFT;
+       if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL)
+               return 0;
+
+       start_index = wbc->range_start >> PAGE_CACHE_SHIFT;
+       end_index = wbc->range_end >> PAGE_CACHE_SHIFT;
        pmd_index = DAX_PMD_INDEX(start_index);
 
        rcu_read_lock();

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 4467cbd..6bd58e6 100644 (file)
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -876,6 +876,14 @@ ext2_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
 static int
 ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
 {
+#ifdef CONFIG_FS_DAX
+       if (dax_mapping(mapping)) {
+               return dax_writeback_mapping_range(mapping,
+                                                  mapping->host->i_sb->s_bdev,
+                                                  wbc);
+       }
+#endif
+
        return mpage_writepages(mapping, wbc, ext2_get_block);
 }
 

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 5708e68..aee960b 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2478,6 +2478,10 @@ static int ext4_writepages(struct address_space *mapping,
 
        trace_ext4_writepages(inode, wbc);
 
+       if (dax_mapping(mapping))
+               return dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,
+                                                  wbc);
+
        /*
         * No pages to write? This is mainly a kludge to avoid starting
         * a transaction for special inodes like journal inode on last iput()

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index fc20518..a9ebabf 100644 (file)
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1208,6 +1208,10 @@ xfs_vm_writepages(
        struct writeback_control *wbc)
 {
        xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
+       if (dax_mapping(mapping))
+               return dax_writeback_mapping_range(mapping,
+                               xfs_find_bdev_for_inode(mapping->host), wbc);
+
        return generic_writepages(mapping, wbc);
 }
 

diff --git a/include/linux/dax.h b/include/linux/dax.h
index 7b6bced..636dd59 100644 (file)
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -52,6 +52,8 @@ static inline bool dax_mapping(struct address_space *mapping)
 {
        return mapping->host && IS_DAX(mapping->host);
 }
-int dax_writeback_mapping_range(struct address_space *mapping, loff_t start,
-               loff_t end);
+
+struct writeback_control;
+int dax_writeback_mapping_range(struct address_space *mapping,
+               struct block_device *bdev, struct writeback_control *wbc);
 #endif

diff --git a/mm/filemap.c b/mm/filemap.c
index 23edcce..3461d97 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -446,7 +446,8 @@ int filemap_write_and_wait(struct address_space *mapping)
 {
        int err = 0;
 
-       if (mapping->nrpages) {
+       if ((!dax_mapping(mapping) && mapping->nrpages) ||
+           (dax_mapping(mapping) && mapping->nrexceptional)) {
                err = filemap_fdatawrite(mapping);
                /*
                 * Even if the above returned error, the pages may be
@@ -482,13 +483,8 @@ int filemap_write_and_wait_range(struct address_space *mapping,
 {
        int err = 0;
 
-       if (dax_mapping(mapping) && mapping->nrexceptional) {
-               err = dax_writeback_mapping_range(mapping, lstart, lend);
-               if (err)
-                       return err;
-       }
-
-       if (mapping->nrpages) {
+       if ((!dax_mapping(mapping) && mapping->nrpages) ||
+           (dax_mapping(mapping) && mapping->nrexceptional)) {
                err = __filemap_fdatawrite_range(mapping, lstart, lend,
                                                 WB_SYNC_ALL);
                /* See comment of filemap_write_and_wait() */