ext4: Properly initialize the buffer_head state
These struct buffer_heads are allocated on the stack (and hence are
initialized with stack garbage). They are only used to call a
get_blocks() function, so that's mostly OK, but b_state must be
initialized to be 0 so we don't have any unexpected BH_* flags set by
accident, such as BH_Unwritten or BH_Delay.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2a9ffd5..d7ad0bb 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2055,7 +2055,20 @@
if ((mpd->b_state & (1 << BH_Mapped)) &&
!(mpd->b_state & (1 << BH_Delay)))
return 0;
- new.b_state = mpd->b_state;
+ /*
+ * We need to make sure the BH_Delay flag is passed down to
+ * ext4_da_get_block_write(), since it calls
+ * ext4_get_blocks_wrap() with the EXT4_DELALLOC_RSVED flag.
+ * This flag causes ext4_get_blocks_wrap() to call
+ * ext4_da_update_reserve_space() if the passed buffer head
+ * has the BH_Delay flag set. In the future, once we clean up
+ * the interfaces to ext4_get_blocks_wrap(), we should pass in
+ * a separate flag which requests that the delayed allocation
+ * statistics should be updated, instead of depending on the
+ * state information getting passed down via the map_bh's
+ * state bitmasks plus the magic EXT4_DELALLOC_RSVED flag.
+ */
+ new.b_state = mpd->b_state & (1 << BH_Delay);
new.b_blocknr = 0;
new.b_size = mpd->b_size;
next = mpd->b_blocknr;