Btrfs: set i_size properly when fallocating and we already

xfstests exposed a problem with preallocate when it fallocates a range that
already has an extent.  We don't set the new i_size properly because we see that
we already have an extent.  This isn't right and we should update i_size if the
space already exists.  With this patch we now pass xfstests 075.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 0705d15542c6..15e5a1cd8764 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1631,11 +1631,15 @@ static long btrfs_fallocate(struct file *file, int mode,
 
         cur_offset = alloc_start;
         while (1) {
+                u64 actual_end;
+
                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
                                       alloc_end - cur_offset, 0);
                 BUG_ON(IS_ERR_OR_NULL(em));
                 last_byte = min(extent_map_end(em), alloc_end);
+                actual_end = min_t(u64, extent_map_end(em), offset + len);
                 last_byte = (last_byte + mask) & ~mask;
+
                 if (em->block_start == EXTENT_MAP_HOLE ||
                     (cur_offset >= inode->i_size &&
                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
@@ -1648,6 +1652,16 @@ static long btrfs_fallocate(struct file *file, int mode,
                                 free_extent_map(em);
                                 break;
                         }
+                } else if (actual_end > inode->i_size &&
+                           !(mode & FALLOC_FL_KEEP_SIZE)) {
+                        /*
+                         * We didn't need to allocate any more space, but we
+                         * still extended the size of the file so we need to
+                         * update i_size.
+                         */
+                        inode->i_ctime = CURRENT_TIME;
+                        i_size_write(inode, actual_end);
+                        btrfs_ordered_update_i_size(inode, actual_end, NULL);
                 }
                 free_extent_map(em);