GitHub-Mirror/linux-bl808
2
0
Fork 0
mirror of https://github.com/Fishwaldo/linux-bl808.git synced 2025-06-17 20:25:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

jbd2: cleanup needed free block estimates when starting a transaction

Browse source 
__jbd2_log_space_left() and jbd_space_needed() were kind of odd.
jbd_space_needed() accounted also credits needed for currently
committing transaction while it didn't account for credits needed for
control blocks.  __jbd2_log_space_left() then accounted for control
blocks as a fraction of free space.  Since results of these two
functions are always only compared against each other, this works
correct but is somewhat strange.  Move the estimates so that
jbd_space_needed() returns number of blocks needed for a transaction
including control blocks and __jbd2_log_space_left() returns free
space in the journal (with the committing transaction already
subtracted).  Rename functions to jbd2_log_space_left() and
jbd2_space_needed() while we are changing them.

Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Jan Kara 2013-06-04 12:12:57 -04:00 • committed by Theodore Ts'o
parent 2f387f849b
commit 76c3990456
4 changed files with 35 additions and 43 deletions
Download patch file Download diff file Expand all files Collapse all files

32
include/linux/jbd2.h
View file

@ -1220,7 +1220,6 @@ extern void jbd2_clear_buffer_revoked_flags(journal_t *journal);
* transitions on demand.
*/
int __jbd2_log_space_left(journal_t *); /* Called with journal locked */
int jbd2_log_start_commit(journal_t *journal, tid_t tid);
int __jbd2_log_start_commit(journal_t *journal, tid_t tid);
int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
@ -1290,17 +1289,38 @@ static inline int tid_geq(tid_t x, tid_t y)
extern int jbd2_journal_blocks_per_page(struct inode *inode);
extern size_t journal_tag_bytes(journal_t *journal);
/*
* We reserve t_outstanding_credits >> JBD2_CONTROL_BLOCKS_SHIFT for
* transaction control blocks.
*/
#define JBD2_CONTROL_BLOCKS_SHIFT 5
/*
* Return the minimum number of blocks which must be free in the journal
* before a new transaction may be started. Must be called under j_state_lock.
*/
static inline int jbd_space_needed(journal_t *journal)
static inline int jbd2_space_needed(journal_t *journal)
{
int nblocks = journal->j_max_transaction_buffers;
if (journal->j_committing_transaction)
nblocks += atomic_read(&journal->j_committing_transaction->
t_outstanding_credits);
return nblocks;
return nblocks + (nblocks >> JBD2_CONTROL_BLOCKS_SHIFT);
}
/*
* Return number of free blocks in the log. Must be called under j_state_lock.
*/
static inline unsigned long jbd2_log_space_left(journal_t *journal)
{
/* Allow for rounding errors */
unsigned long free = journal->j_free - 32;
if (journal->j_committing_transaction) {
unsigned long committing = atomic_read(&journal->
j_committing_transaction->t_outstanding_credits);
/* Transaction + control blocks */
free -= committing + (committing >> JBD2_CONTROL_BLOCKS_SHIFT);
}
return free;
}
/*