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authorAmir Goldstein <amir73il@gmail.com>2011-03-20 20:08:48 -0400
committerTheodore Ts'o <tytso@mit.edu>2011-03-20 20:08:48 -0400
commitc2cc7028e41c76e44b6e247c4b495c7523b23c87 (patch)
tree747b3152285a95ec9727463cc3ae8cee2509521c
parent688f869ce3bdc892daa993534dc6df18c95df931 (diff)
downloadop-kernel-dev-c2cc7028e41c76e44b6e247c4b495c7523b23c87.zip
op-kernel-dev-c2cc7028e41c76e44b6e247c4b495c7523b23c87.tar.gz
jbd2: add the b_cow_tid field to journal_head struct
The b_cow_tid field will be used by the ext4 snapshots code to store the transaction id when the buffer was last cowed. Merging this patch to mainline will allow users to test ext4 snapshots as a standalone module, without the need to patch and install a development kernel. On 64bit machines this field uses fills in a padding "hole" and does not increase the size of the struct. On a 32bit machine this patch increases the size of the struct from 60 to 64 bytes. Signed-off-by: Amir Goldstein <amir73il@users.sf.net> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
-rw-r--r--include/linux/journal-head.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/journal-head.h b/include/linux/journal-head.h
index 525aac3..44e95d0 100644
--- a/include/linux/journal-head.h
+++ b/include/linux/journal-head.h
@@ -41,6 +41,13 @@ struct journal_head {
unsigned b_modified;
/*
+ * This feild tracks the last transaction id in which this buffer
+ * has been cowed
+ * [jbd_lock_bh_state()]
+ */
+ unsigned b_cow_tid;
+
+ /*
* Copy of the buffer data frozen for writing to the log.
* [jbd_lock_bh_state()]
*/
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