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xfs: add a helper to figure out the space log reservation per item

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Add a new helper xfs_calc_buf_res() to calcuate out the transaction space
reservations per item.  xfs_buf_log_overhead() is used to figure out the
extra space for struct xfs_buf_log_format that gets written into the log
for every buffer as well as a log opheader, i.e. struct xlog_op_header.

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
CC: Dave Chinner <david@fromorbit.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
This commit is contained in:
Jeff Liu 2013-01-28 21:25:35 +08:00 committed by Ben Myers
parent 2729423cf2
commit 4f3b57832b
1 changed files with 31 additions and 0 deletions
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31
fs/xfs/xfs_trans.c
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@ -37,14 +37,45 @@
#include "xfs_extent_busy.h"
#include "xfs_bmap.h"
#include "xfs_quota.h"
#include "xfs_qm.h"
#include "xfs_trans_priv.h"
#include "xfs_trans_space.h"
#include "xfs_inode_item.h"
#include "xfs_log_priv.h"
#include "xfs_buf_item.h"
#include "xfs_trace.h"
kmem_zone_t *xfs_trans_zone;
kmem_zone_t *xfs_log_item_desc_zone;
/*
* A buffer has a format structure overhead in the log in addition
* to the data, so we need to take this into account when reserving
* space in a transaction for a buffer. Round the space required up
* to a multiple of 128 bytes so that we don't change the historical
* reservation that has been used for this overhead.
*/
STATIC uint
xfs_buf_log_overhead(void)
{
return round_up(sizeof(struct xlog_op_header) +
sizeof(struct xfs_buf_log_format), 128);
}
/*
* Calculate out transaction log reservation per item in bytes.
*
* The nbufs argument is used to indicate the number of items that
* will be changed in a transaction. size is used to tell how many
* bytes should be reserved per item.
*/
STATIC uint
xfs_calc_buf_res(
uint nbufs,
uint size)
{
return nbufs * (size + xfs_buf_log_overhead());
}
/*
* Various log reservation values.