From c2cc7028e41c76e44b6e247c4b495c7523b23c87 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Sun, 20 Mar 2011 20:08:48 -0400 Subject: 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 Signed-off-by: "Theodore Ts'o" --- include/linux/journal-head.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux') diff --git a/include/linux/journal-head.h b/include/linux/journal-head.h index 525aac3c97df..44e95d0a721f 100644 --- a/include/linux/journal-head.h +++ b/include/linux/journal-head.h @@ -40,6 +40,13 @@ 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()] -- cgit v1.2.3 From 93737456d68ddcb86232f669b83da673dd12e351 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Sun, 20 Mar 2011 21:13:43 -0400 Subject: jbd2: add COW fields to struct jbd2_journal_handle Add fields needed for the copy-on-write ext4 development work. The h_cowing flag is used by ext4 snapshots code to mark the task in COWING state. The h_XXX_credits fields are used to track buffer credits usage (accounted by COW and non-COW operations). The h_cow_XXX fields are used as per task debugging counters. Merging this commit into mainline will allow users to test ext4 snapshots as a standalone module, without the need to patch and install a development kernel. Signed-off-by: Amir Goldstein Signed-off-by: "Theodore Ts'o" --- include/linux/jbd2.h | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 27e79c27ba08..a32dcaec04e1 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -432,13 +432,35 @@ struct jbd2_journal_handle int h_err; /* Flags [no locking] */ - unsigned int h_sync: 1; /* sync-on-close */ - unsigned int h_jdata: 1; /* force data journaling */ - unsigned int h_aborted: 1; /* fatal error on handle */ + unsigned int h_sync:1; /* sync-on-close */ + unsigned int h_jdata:1; /* force data journaling */ + unsigned int h_aborted:1; /* fatal error on handle */ + unsigned int h_cowing:1; /* COWing block to snapshot */ + + /* Number of buffers requested by user: + * (before adding the COW credits factor) */ + unsigned int h_base_credits:14; + + /* Number of buffers the user is allowed to dirty: + * (counts only buffers dirtied when !h_cowing) */ + unsigned int h_user_credits:14; + #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map h_lockdep_map; #endif + +#ifdef CONFIG_JBD2_DEBUG + /* COW debugging counters: */ + unsigned int h_cow_moved; /* blocks moved to snapshot */ + unsigned int h_cow_copied; /* blocks copied to snapshot */ + unsigned int h_cow_ok_jh; /* blocks already COWed during current + transaction */ + unsigned int h_cow_ok_bitmap; /* blocks not set in COW bitmap */ + unsigned int h_cow_ok_mapped;/* blocks already mapped in snapshot */ + unsigned int h_cow_bitmaps; /* COW bitmaps created */ + unsigned int h_cow_excluded; /* blocks set in exclude bitmap */ +#endif }; -- cgit v1.2.3