1 files changed, 14 insertions, 8 deletions

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index f96c8ffce5f4..c08253e11545 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -934,11 +934,13 @@ error_on_bmapi_transaction:
         return error;
 }
 
-static inline bool imap_needs_alloc(struct xfs_bmbt_irec *imap, int nimaps)
+static inline bool imap_needs_alloc(struct inode *inode,
+                struct xfs_bmbt_irec *imap, int nimaps)
 {
         return !nimaps ||
                 imap->br_startblock == HOLESTARTBLOCK ||
-                imap->br_startblock == DELAYSTARTBLOCK;
+                imap->br_startblock == DELAYSTARTBLOCK ||
+                (IS_DAX(inode) && ISUNWRITTEN(imap));
 }
 
 static int
@@ -954,16 +956,18 @@ xfs_file_iomap_begin(
         struct xfs_bmbt_irec    imap;
         xfs_fileoff_t           offset_fsb, end_fsb;
         int                     nimaps = 1, error = 0;
+        unsigned                lockmode;
 
         if (XFS_FORCED_SHUTDOWN(mp))
                 return -EIO;
 
-        if ((flags & IOMAP_WRITE) && !xfs_get_extsz_hint(ip)) {
+        if ((flags & IOMAP_WRITE) &&
+            !IS_DAX(inode) && !xfs_get_extsz_hint(ip)) {
                 return xfs_file_iomap_begin_delay(inode, offset, length, flags,
                                 iomap);
         }
 
-        xfs_ilock(ip, XFS_ILOCK_EXCL);
+        lockmode = xfs_ilock_data_map_shared(ip);
 
         ASSERT(offset <= mp->m_super->s_maxbytes);
         if ((xfs_fsize_t)offset + length > mp->m_super->s_maxbytes)
@@ -974,11 +978,11 @@ xfs_file_iomap_begin(
         error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
                                &nimaps, XFS_BMAPI_ENTIRE);
         if (error) {
-                xfs_iunlock(ip, XFS_ILOCK_EXCL);
+                xfs_iunlock(ip, lockmode);
                 return error;
         }
 
-        if ((flags & IOMAP_WRITE) && imap_needs_alloc(&imap, nimaps)) {
+        if ((flags & IOMAP_WRITE) && imap_needs_alloc(inode, &imap, nimaps)) {
                 /*
                  * We cap the maximum length we map here to MAX_WRITEBACK_PAGES
                  * pages to keep the chunks of work done where somewhat symmetric
@@ -994,17 +998,19 @@ xfs_file_iomap_begin(
                  * xfs_iomap_write_direct() expects the shared lock. It
                  * is unlocked on return.
                  */
-                xfs_ilock_demote(ip, XFS_ILOCK_EXCL);
+                if (lockmode == XFS_ILOCK_EXCL)
+                        xfs_ilock_demote(ip, lockmode);
                 error = xfs_iomap_write_direct(ip, offset, length, &imap,
                                 nimaps);
                 if (error)
                         return error;
 
+                iomap->flags = IOMAP_F_NEW;
                 trace_xfs_iomap_alloc(ip, offset, length, 0, &imap);
         } else {
                 ASSERT(nimaps);
 
-                xfs_iunlock(ip, XFS_ILOCK_EXCL);
+                xfs_iunlock(ip, lockmode);
                 trace_xfs_iomap_found(ip, offset, length, 0, &imap);
         }