From 4f3b57832ba39223c6f8823d07b9fb206e282ced Mon Sep 17 00:00:00 2001 From: Jeff Liu Date: Mon, 28 Jan 2013 21:25:35 +0800 Subject: xfs: add a helper to figure out the space log reservation per item 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 CC: Dave Chinner Reviewed-by: Mark Tinguely Signed-off-by: Ben Myers --- fs/xfs/xfs_trans.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'fs/xfs') diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c index 06ed520a767f..6c601ea77a9e 100644 --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c @@ -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. -- cgit v1.2.3-58-ga151