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Commit 93737456 authored by Amir Goldstein's avatar Amir Goldstein Committed by Theodore Ts'o
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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: default avatarAmir Goldstein <amir73il@users.sf.net>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent c2cc7028

include/linux/jbd2.h

+25 −3
Original line number Diff line number Diff line
@@ -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

};