Commit 9bd23c31 authored by Harshad Shirwadkar's avatar Harshad Shirwadkar Committed by Theodore Ts'o
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jbd2: add a helper to find out number of fast commit blocks 



Add a helper to read number of fast commit blocks from jbd2 superblock
and also rename the JBD2_MIN_FC_BLKS to
JBD2_DEFAULT_FAST_COMMIT_BLOCKS since this constant is just the
default number of fast commit blocks to use in case number of fast
commit blocks isn't set in jbd2 superblock.

Signed-off-by: default avatarHarshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201120202232.2240293-2-harshadshirwadkar@gmail.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 941ba122

fs/jbd2/journal.c

+2 −6
Original line number Diff line number Diff line
@@ -1869,9 +1869,7 @@ static int load_superblock(journal_t *journal) 


	if (jbd2_has_feature_fast_commit(journal)) {

		journal->j_fc_last = be32_to_cpu(sb->s_maxlen);

		num_fc_blocks = be32_to_cpu(sb->s_num_fc_blks);

		if (!num_fc_blocks)

			num_fc_blocks = JBD2_MIN_FC_BLOCKS;

		num_fc_blocks = jbd2_journal_get_num_fc_blks(sb);

		if (journal->j_last - num_fc_blocks >= JBD2_MIN_JOURNAL_BLOCKS)

			journal->j_last = journal->j_fc_last - num_fc_blocks;

		journal->j_fc_first = journal->j_last + 1;
@@ -2102,9 +2100,7 @@ jbd2_journal_initialize_fast_commit(journal_t *journal) 
	journal_superblock_t *sb = journal->j_superblock;

	unsigned long long num_fc_blks;



	num_fc_blks = be32_to_cpu(sb->s_num_fc_blks);

	if (num_fc_blks == 0)

		num_fc_blks = JBD2_MIN_FC_BLOCKS;

	num_fc_blks = jbd2_journal_get_num_fc_blks(sb);

	if (journal->j_last - num_fc_blks < JBD2_MIN_JOURNAL_BLOCKS)

		return -ENOSPC;

include/linux/jbd2.h

+8 −1
Original line number Diff line number Diff line
@@ -68,7 +68,7 @@ extern void *jbd2_alloc(size_t size, gfp_t flags); 
extern void jbd2_free(void *ptr, size_t size);



#define JBD2_MIN_JOURNAL_BLOCKS 1024

#define JBD2_MIN_FC_BLOCKS	256

#define JBD2_DEFAULT_FAST_COMMIT_BLOCKS 256



#ifdef __KERNEL__
@@ -1692,6 +1692,13 @@ static inline int jbd2_journal_has_csum_v2or3(journal_t *journal) 
	return journal->j_chksum_driver != NULL;

}



static inline int jbd2_journal_get_num_fc_blks(journal_superblock_t *jsb)

{

	int num_fc_blocks = be32_to_cpu(jsb->s_num_fc_blks);



	return num_fc_blocks ? num_fc_blocks : JBD2_DEFAULT_FAST_COMMIT_BLOCKS;

}



/*

 * Return number of free blocks in the log. Must be called under j_state_lock.

 */

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