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xfs: combine grant heads into a single 64 bit integer

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Prepare for switching the grant heads to atomic variables by
combining the two 32 bit values that make up the grant head into a
single 64 bit variable.  Provide wrapper functions to combine and
split the grant heads appropriately for calculations and use them as
necessary.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Dave Chinner
2010-12-21 12:08:20 +11:00
committed by Dave Chinner
parent 663e496a72
commit a69ed03c24
4 changed files with 119 additions and 91 deletions
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26
fs/xfs/xfs_log_priv.h
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@@ -518,10 +518,8 @@ typedef struct log {
spinlock_t l_grant_lock ____cacheline_aligned_in_smp;
struct list_head l_reserveq;
struct list_head l_writeq;
int l_grant_reserve_cycle;
int l_grant_reserve_bytes;
int l_grant_write_cycle;
int l_grant_write_bytes;
int64_t l_grant_reserve_head;
int64_t l_grant_write_head;
/* The following field are used for debugging; need to hold icloglock */
#ifdef DEBUG
@@ -560,6 +558,26 @@ int xlog_write(struct log *log, struct xfs_log_vec *log_vector,
struct xlog_ticket *tic, xfs_lsn_t *start_lsn,
xlog_in_core_t **commit_iclog, uint flags);
/*
* When we crack the grrant head, we sample it first so that the value will not
* change while we are cracking it into the component values. This means we
* will always get consistent component values to work from.
*/
static inline void
xlog_crack_grant_head(int64_t *head, int *cycle, int *space)
{
int64_t val = *head;
*cycle = val >> 32;
*space = val & 0xffffffff;
}
static inline void
xlog_assign_grant_head(int64_t *head, int cycle, int space)
{
*head = ((int64_t)cycle << 32) | space;
}
/*
* Committed Item List interfaces
*/