Btrfs: fix leaf corruption caused by ENOSPC while hole punching

[platform/kernel/linux-rpi.git] / fs / btrfs / file.c

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index ae6af07..3029925 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -780,6 +780,18 @@ next_slot:
                        extent_end = search_start;
                }
 
+               /*
+                * Don't skip extent items representing 0 byte lengths. They
+                * used to be created (bug) if while punching holes we hit
+                * -ENOSPC condition. So if we find one here, just ensure we
+                * delete it, otherwise we would insert a new file extent item
+                * with the same key (offset) as that 0 bytes length file
+                * extent item in the call to setup_items_for_insert() later
+                * in this function.
+                */
+               if (extent_end == key.offset && extent_end >= search_start)
+                       goto delete_extent_item;
+
                if (extent_end <= search_start) {
                        path->slots[0]++;
                        goto next_slot;
@@ -893,6 +905,7 @@ next_slot:
                 *    | ------ extent ------ |
                 */
                if (start <= key.offset && end >= extent_end) {
+delete_extent_item:
                        if (del_nr == 0) {
                                del_slot = path->slots[0];
                                del_nr = 1;
@@ -2187,13 +2200,14 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
        bool same_page = ((offset >> PAGE_CACHE_SHIFT) ==
                          ((offset + len - 1) >> PAGE_CACHE_SHIFT));
        bool no_holes = btrfs_fs_incompat(root->fs_info, NO_HOLES);
-       u64 ino_size = round_up(inode->i_size, PAGE_CACHE_SIZE);
+       u64 ino_size;
 
        ret = btrfs_wait_ordered_range(inode, offset, len);
        if (ret)
                return ret;
 
        mutex_lock(&inode->i_mutex);
+       ino_size = round_up(inode->i_size, PAGE_CACHE_SIZE);
        /*
         * We needn't truncate any page which is beyond the end of the file
         * because we are sure there is no data there.
@@ -2347,7 +2361,12 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
        }
 
        trans->block_rsv = &root->fs_info->trans_block_rsv;
-       if (cur_offset < ino_size) {
+       /*
+        * Don't insert file hole extent item if it's for a range beyond eof
+        * (because it's useless) or if it represents a 0 bytes range (when
+        * cur_offset == drop_end).
+        */
+       if (cur_offset < ino_size && cur_offset < drop_end) {
                ret = fill_holes(trans, inode, path, cur_offset, drop_end);
                if (ret) {
                        err = ret;