/*
* This returns the number of log iovecs needed to log the given buf log item.
*
* It calculates this as 1 iovec for the buf log format structure and 1 for each
* stretch of non-contiguous chunks to be logged. Contiguous chunks are logged
* in a single iovec.
*
* Discontiguous buffers need a format structure per region that that is being
* logged. This makes the changes in the buffer appear to log recovery as though
* they came from separate buffers, just like would occur if multiple buffers
* were used instead of a single discontiguous buffer. This enables
* discontiguous buffers to be in-memory constructs, completely transparent to
* what ends up on disk.
*
* If the XFS_BLI_STALE flag has been set, then log nothing but the buf log
* format structures.
*/
STATIC void
xfs_buf_item_size(
struct xfs_log_item *lip,
int *nvecs,
int *nbytes)
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
int i;
ASSERT(atomic_read(&bip->bli_refcount) > 0);
if (bip->bli_flags & XFS_BLI_STALE) {
/*
* The buffer is stale, so all we need to log
* is the buf log format structure with the
* cancel flag in it.
*/
trace_xfs_buf_item_size_stale(bip);
ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
*nvecs += bip->bli_format_count;
for (i = 0; i < bip->bli_format_count; i++) {
*nbytes += xfs_buf_log_format_size(&bip->bli_formats[i]);
}
return;
}
ASSERT(bip->bli_flags & XFS_BLI_LOGGED);
if (bip->bli_flags & XFS_BLI_ORDERED) {
/*
* The buffer has been logged just to order it.
* It is not being included in the transaction
* commit, so no vectors are used at all.
*/
trace_xfs_buf_item_size_ordered(bip);
*nvecs = XFS_LOG_VEC_ORDERED;
return;
}
/*
* the vector count is based on the number of buffer vectors we have
* dirty bits in. This will only be greater than one when we have a
* compound buffer with more than one segment dirty. Hence for compound
* buffers we need to track which segment the dirty bits correspond to,
* and when we move from one segment to the next increment the vector
* count for the extra buf log format structure that will need to be
* written.
*/
for (i = 0; i < bip->bli_format_count; i++) {
xfs_buf_item_size_segment(bip, &bip->bli_formats[i],
nvecs, nbytes);
}
trace_xfs_buf_item_size(bip);
}
/*
* This returns the number of log iovecs needed to log the given buf log item.
*
* It calculates this as 1 iovec for the buf log format structure and 1 for each
* stretch of non-contiguous chunks to be logged. Contiguous chunks are logged
* in a single iovec.
*
* Discontiguous buffers need a format structure per region that that is being
* logged. This makes the changes in the buffer appear to log recovery as though
* they came from separate buffers, just like would occur if multiple buffers
* were used instead of a single discontiguous buffer. This enables
* discontiguous buffers to be in-memory constructs, completely transparent to
* what ends up on disk.
*
* If the XFS_BLI_STALE flag has been set, then log nothing but the buf log
* format structures.
*/
STATIC uint
xfs_buf_item_size(
struct xfs_log_item *lip)
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
uint nvecs;
int i;
ASSERT(atomic_read(&bip->bli_refcount) > 0);
if (bip->bli_flags & XFS_BLI_STALE) {
/*
* The buffer is stale, so all we need to log
* is the buf log format structure with the
* cancel flag in it.
*/
trace_xfs_buf_item_size_stale(bip);
ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
return bip->bli_format_count;
}
ASSERT(bip->bli_flags & XFS_BLI_LOGGED);
/*
* the vector count is based on the number of buffer vectors we have
* dirty bits in. This will only be greater than one when we have a
* compound buffer with more than one segment dirty. Hence for compound
* buffers we need to track which segment the dirty bits correspond to,
* and when we move from one segment to the next increment the vector
* count for the extra buf log format structure that will need to be
* written.
*/
nvecs = 0;
for (i = 0; i < bip->bli_format_count; i++) {
nvecs += xfs_buf_item_size_segment(bip, &bip->bli_formats[i]);
}
trace_xfs_buf_item_size(bip);
return nvecs;
}
/*
* This returns the number of log iovecs needed to log the
* given buf log item.
*
* It calculates this as 1 iovec for the buf log format structure
* and 1 for each stretch of non-contiguous chunks to be logged.
* Contiguous chunks are logged in a single iovec.
*
* If the XFS_BLI_STALE flag has been set, then log nothing.
*/
STATIC uint
xfs_buf_item_size(
struct xfs_log_item *lip)
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
struct xfs_buf *bp = bip->bli_buf;
uint nvecs;
int next_bit;
int last_bit;
ASSERT(atomic_read(&bip->bli_refcount) > 0);
if (bip->bli_flags & XFS_BLI_STALE) {
/*
* The buffer is stale, so all we need to log
* is the buf log format structure with the
* cancel flag in it.
*/
trace_xfs_buf_item_size_stale(bip);
ASSERT(bip->bli_format.blf_flags & XFS_BLF_CANCEL);
return 1;
}
ASSERT(bip->bli_flags & XFS_BLI_LOGGED);
nvecs = 1;
last_bit = xfs_next_bit(bip->bli_format.blf_data_map,
bip->bli_format.blf_map_size, 0);
ASSERT(last_bit != -1);
nvecs++;
while (last_bit != -1) {
/*
* This takes the bit number to start looking from and
* returns the next set bit from there. It returns -1
* if there are no more bits set or the start bit is
* beyond the end of the bitmap.
*/
next_bit = xfs_next_bit(bip->bli_format.blf_data_map,
bip->bli_format.blf_map_size,
last_bit + 1);
/*
* If we run out of bits, leave the loop,
* else if we find a new set of bits bump the number of vecs,
* else keep scanning the current set of bits.
*/
if (next_bit == -1) {
last_bit = -1;
} else if (next_bit != last_bit + 1) {
last_bit = next_bit;
nvecs++;
} else if (xfs_buf_offset(bp, next_bit * XFS_BLF_CHUNK) !=
(xfs_buf_offset(bp, last_bit * XFS_BLF_CHUNK) +
XFS_BLF_CHUNK)) {
last_bit = next_bit;
nvecs++;
} else {
last_bit++;
}
}
trace_xfs_buf_item_size(bip);
return nvecs;
}
