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| author | Jan Kara <jack@suse.cz> | 2013-06-04 20:12:57 +0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2013-06-04 20:12:57 +0400 |
| commit | 76c39904561004ac8675f858a290129e439d5168 (patch) | |
| tree | 46b2c2800ffbad5dd2ebd4ceb66893414630df2b /include/linux/jbd2.h | |
| parent | 2f387f849b6a5be5b4b914c43a8af0406279db11 (diff) | |
| download | linux-76c39904561004ac8675f858a290129e439d5168.tar.xz | |
jbd2: cleanup needed free block estimates when starting a transaction
__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>
Diffstat (limited to 'include/linux/jbd2.h')
| -rw-r--r-- | include/linux/jbd2.h | 32 |
1 files changed, 26 insertions, 6 deletions
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index e33e84b3d5c8..7a1f6cd864c8 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -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); @@ -1291,16 +1290,37 @@ 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; } /* |