xfs: support returning partial reflink results

Back when the XFS reflink code only supported clone_file_range, we were
only able to return zero or negative error codes to userspace.  However,
now that copy_file_range (which returns bytes copied) can use XFS'
clone_file_range, we have the opportunity to return partial results.
For example, if userspace sends a 1GB clone request and we run out of
space halfway through, we at least can tell userspace that we completed
512M of that request like a regular write.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 38fde4e11714860428ac30a472ce8795e2aa0db6..7d42ab8fe6e1ef40124d23a88e465e124a6bf1bc 100644 (file)
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -928,14 +928,11 @@ xfs_file_remap_range(
        loff_t          len,
        unsigned int    remap_flags)
 {
-       int             ret;
-
        if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
                return -EINVAL;
 
-       ret = xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
+       return xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
                        len, remap_flags);
-       return ret < 0 ? ret : len;
 }
 
 STATIC int

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 79dec457f7fb3cab6dd42a74e7614d339e1b2490..4abb2aea8f314bcf20db07c2f0df09fd7d93fb3d 100644 (file)
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1122,13 +1122,15 @@ xfs_reflink_remap_blocks(
        loff_t                  pos_in,
        struct xfs_inode        *dest,
        loff_t                  pos_out,
-       loff_t                  remap_len)
+       loff_t                  remap_len,
+       loff_t                  *remapped)
 {
        struct xfs_bmbt_irec    imap;
        xfs_fileoff_t           srcoff;
        xfs_fileoff_t           destoff;
        xfs_filblks_t           len;
        xfs_filblks_t           range_len;
+       xfs_filblks_t           remapped_len = 0;
        xfs_off_t               new_isize = pos_out + remap_len;
        int                     nimaps;
        int                     error = 0;
@@ -1175,10 +1177,13 @@ xfs_reflink_remap_blocks(
                srcoff += range_len;
                destoff += range_len;
                len -= range_len;
+               remapped_len += range_len;
        }
 
        if (error)
                trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
+       *remapped = min_t(loff_t, remap_len,
+                         XFS_FSB_TO_B(src->i_mount, remapped_len));
        return error;
 }
 
@@ -1387,7 +1392,7 @@ xfs_reflink_remap_prep(
 /*
  * Link a range of blocks from one file to another.
  */
-int
+loff_t
 xfs_reflink_remap_range(
        struct file             *file_in,
        loff_t                  pos_in,
@@ -1401,8 +1406,9 @@ xfs_reflink_remap_range(
        struct inode            *inode_out = file_inode(file_out);
        struct xfs_inode        *dest = XFS_I(inode_out);
        struct xfs_mount        *mp = src->i_mount;
+       loff_t                  remapped = 0;
        xfs_extlen_t            cowextsize;
-       ssize_t                 ret;
+       int                     ret;
 
        if (!xfs_sb_version_hasreflink(&mp->m_sb))
                return -EOPNOTSUPP;
@@ -1418,7 +1424,8 @@ xfs_reflink_remap_range(
 
        trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out);
 
-       ret = xfs_reflink_remap_blocks(src, pos_in, dest, pos_out, len);
+       ret = xfs_reflink_remap_blocks(src, pos_in, dest, pos_out, len,
+                       &remapped);
        if (ret)
                goto out_unlock;
 
@@ -1441,7 +1448,7 @@ xfs_reflink_remap_range(
        xfs_reflink_remap_unlock(file_in, file_out);
        if (ret)
                trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
-       return ret;
+       return remapped > 0 ? remapped : ret;
 }
 
 /*

diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
index c3c46c276fe18a2eef81c870329831993cb3b84c..cbc26ff79a8f3bc6705d03966f58843405b37833 100644 (file)
--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -27,7 +27,7 @@ extern int xfs_reflink_cancel_cow_range(struct xfs_inode *ip, xfs_off_t offset,
 extern int xfs_reflink_end_cow(struct xfs_inode *ip, xfs_off_t offset,
                xfs_off_t count);
 extern int xfs_reflink_recover_cow(struct xfs_mount *mp);
-extern int xfs_reflink_remap_range(struct file *file_in, loff_t pos_in,
+extern loff_t xfs_reflink_remap_range(struct file *file_in, loff_t pos_in,
                struct file *file_out, loff_t pos_out, loff_t len,
                unsigned int remap_flags);
 extern int xfs_reflink_inode_has_shared_extents(struct xfs_trans *tp,