bcachefs: fix truncate without a size change

Do not attempt to shortcut a truncate when the given new size is
the same as the current size. There may be blocks allocated to the
file that extend beyond the i_size. The ctime and mtime should
not be updated in this case.

Signed-off-by: Dan Robertson <dan@dlrobertson.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/fs-io.c b/fs/bcachefs/fs-io.c
index a25c3b70ef7407f733689aec717a9fdaa7d10fc3..bcf954a2394f1cc91685680eb91654edd1a47ea1 100644 (file)
--- a/fs/bcachefs/fs-io.c
+++ b/fs/bcachefs/fs-io.c
@@ -2305,16 +2305,17 @@ int bch2_truncate(struct mnt_idmap *idmap,
        int ret = 0;
 
        /*
-        * Don't update timestamps if we're not doing anything:
+        * If the truncate call with change the size of the file, the
+        * cmtimes should be updated. If the size will not change, we
+        * do not need to update the cmtimes.
         */
-       if (iattr->ia_size == inode->v.i_size)
-               return 0;
-
-       if (!(iattr->ia_valid & ATTR_MTIME))
-               ktime_get_coarse_real_ts64(&iattr->ia_mtime);
-       if (!(iattr->ia_valid & ATTR_CTIME))
-               ktime_get_coarse_real_ts64(&iattr->ia_ctime);
-       iattr->ia_valid |= ATTR_MTIME|ATTR_CTIME;
+       if (iattr->ia_size != inode->v.i_size) {
+               if (!(iattr->ia_valid & ATTR_MTIME))
+                       ktime_get_coarse_real_ts64(&iattr->ia_mtime);
+               if (!(iattr->ia_valid & ATTR_CTIME))
+                       ktime_get_coarse_real_ts64(&iattr->ia_ctime);
+               iattr->ia_valid |= ATTR_MTIME|ATTR_CTIME;
+       }
 
        inode_dio_wait(&inode->v);
        bch2_pagecache_block_get(&inode->ei_pagecache_lock);