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 patch to kernel 2.6.39, will allow users to test ext4 snapshots as a standalone module (with debug counters enabled), without the need to patch and install a development kernel. With CONFIG_JBD2_DEBUG not defined, this patch doesn't change the size of the struct. With CONFIG_JBD2_DEBUG defined, the struct grows by 7 int fields, but since CONFIG_JBD2_DEBUG is mostly defined on development kernels, and since the size of objects associated with a task is much larger that 7 ints, that doesn't seem to be a big problem. Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxxxxx> --- include/linux/jbd2.h | 22 ++++++++++++++++++++++ 1 files changed, 22 insertions(+), 0 deletions(-) diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 27e79c2..1f22e43 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -435,10 +435,32 @@ struct jbd2_journal_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 }; -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
