dax: remove buffer_size_valid()

Now that ext4 properly sets bh.b_size when we call get_block() for a hole,
rely on that value and remove the buffer_size_valid() sanity check.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/dax.c b/fs/dax.c
index 014defd2e744e00b4df273e88d2a7026a3db4ff9..b09817ac6f875f454a6a206f703de0ec78484dac 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -123,19 +123,6 @@ static bool buffer_written(struct buffer_head *bh)
        return buffer_mapped(bh) && !buffer_unwritten(bh);
 }
 
-/*
- * When ext4 encounters a hole, it returns without modifying the buffer_head
- * which means that we can't trust b_size.  To cope with this, we set b_state
- * to 0 before calling get_block and, if any bit is set, we know we can trust
- * b_size.  Unfortunate, really, since ext4 knows precisely how long a hole is
- * and would save us time calling get_block repeatedly.
- */
-static bool buffer_size_valid(struct buffer_head *bh)
-{
-       return bh->b_state != 0;
-}
-
-
 static sector_t to_sector(const struct buffer_head *bh,
                const struct inode *inode)
 {
@@ -177,8 +164,6 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
                                rc = get_block(inode, block, bh, rw == WRITE);
                                if (rc)
                                        break;
-                               if (!buffer_size_valid(bh))
-                                       bh->b_size = 1 << blkbits;
                                bh_max = pos - first + bh->b_size;
                                bdev = bh->b_bdev;
                                /*
@@ -1012,12 +997,7 @@ int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 
        bdev = bh.b_bdev;
 
-       /*
-        * If the filesystem isn't willing to tell us the length of a hole,
-        * just fall back to PTEs.  Calling get_block 512 times in a loop
-        * would be silly.
-        */
-       if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) {
+       if (bh.b_size < PMD_SIZE) {
                dax_pmd_dbg(&bh, address, "allocated block too small");
                return VM_FAULT_FALLBACK;
        }