1 files changed, 46 insertions, 18 deletions

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 3b65f67bb38e..aa3a4ddb834e 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -366,8 +366,15 @@ static int gfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
         unsigned int data_blocks, ind_blocks, rblocks;
         struct gfs2_holder gh;
         struct gfs2_alloc *al;
+        loff_t size;
         int ret;
 
+        /* Wait if fs is frozen. This is racy so we check again later on
+         * and retry if the fs has been frozen after the page lock has
+         * been acquired
+         */
+        vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+
         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
         ret = gfs2_glock_nq(&gh);
         if (ret)
@@ -376,8 +383,15 @@ static int gfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
         set_bit(GLF_DIRTY, &ip->i_gl->gl_flags);
         set_bit(GIF_SW_PAGED, &ip->i_flags);
 
-        if (!gfs2_write_alloc_required(ip, pos, PAGE_CACHE_SIZE))
+        if (!gfs2_write_alloc_required(ip, pos, PAGE_CACHE_SIZE)) {
+                lock_page(page);
+                if (!PageUptodate(page) || page->mapping != inode->i_mapping) {
+                        ret = -EAGAIN;
+                        unlock_page(page);
+                }
                 goto out_unlock;
+        }
+
         ret = -ENOMEM;
         al = gfs2_alloc_get(ip);
         if (al == NULL)
@@ -405,21 +419,29 @@ static int gfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 
         lock_page(page);
         ret = -EINVAL;
-        last_index = ip->i_inode.i_size >> PAGE_CACHE_SHIFT;
-        if (page->index > last_index)
-                goto out_unlock_page;
+        size = i_size_read(inode);
+        last_index = (size - 1) >> PAGE_CACHE_SHIFT;
+        /* Check page index against inode size */
+        if (size == 0 || (page->index > last_index))
+                goto out_trans_end;
+
+        ret = -EAGAIN;
+        /* If truncated, we must retry the operation, we may have raced
+         * with the glock demotion code.
+         */
+        if (!PageUptodate(page) || page->mapping != inode->i_mapping)
+                goto out_trans_end;
+
+        /* Unstuff, if required, and allocate backing blocks for page */
         ret = 0;
-        if (!PageUptodate(page) || page->mapping != ip->i_inode.i_mapping)
-                goto out_unlock_page;
-        if (gfs2_is_stuffed(ip)) {
+        if (gfs2_is_stuffed(ip))
                 ret = gfs2_unstuff_dinode(ip, page);
-                if (ret)
-                        goto out_unlock_page;
-        }
-        ret = gfs2_allocate_page_backing(page);
+        if (ret == 0)
+                ret = gfs2_allocate_page_backing(page);
 
-out_unlock_page:
-        unlock_page(page);
+out_trans_end:
+        if (ret)
+                unlock_page(page);
         gfs2_trans_end(sdp);
 out_trans_fail:
         gfs2_inplace_release(ip);
@@ -431,11 +453,17 @@ out_unlock:
         gfs2_glock_dq(&gh);
 out:
         gfs2_holder_uninit(&gh);
-        if (ret == -ENOMEM)
-                ret = VM_FAULT_OOM;
-        else if (ret)
-                ret = VM_FAULT_SIGBUS;
-        return ret;
+        if (ret == 0) {
+                set_page_dirty(page);
+                /* This check must be post dropping of transaction lock */
+                if (inode->i_sb->s_frozen == SB_UNFROZEN) {
+                        wait_on_page_writeback(page);
+                } else {
+                        ret = -EAGAIN;
+                        unlock_page(page);
+                }
+        }
+        return block_page_mkwrite_return(ret);
 }
 
 static const struct vm_operations_struct gfs2_vm_ops = {