biodoc.txt
- Notes on the Generic Block Layer Rewrite in Linux 2.5
capability.txt
- - Generic Block Device Capability (/sys/block/<disk>/capability)
+ - Generic Block Device Capability (/sys/block/<device>/capability)
+cfq-iosched.txt
+ - CFQ IO scheduler tunables
+data-integrity.txt
+ - Block data integrity
deadline-iosched.txt
- Deadline IO scheduler tunables
ioprio.txt
- Block io priorities (in CFQ scheduler)
+queue-sysfs.txt
+ - Queue's sysfs entries
request.txt
- The members of struct request (in include/linux/blkdev.h)
stat.txt
- - Block layer statistics in /sys/block/<dev>/stat
+ - Block layer statistics in /sys/block/<device>/stat
switching-sched.txt
- Switching I/O schedulers at runtime
writeback_cache_control.txt
+CFQ (Complete Fairness Queueing)
+===============================
+
+The main aim of CFQ scheduler is to provide a fair allocation of the disk
+I/O bandwidth for all the processes which requests an I/O operation.
+
+CFQ maintains the per process queue for the processes which request I/O
+operation(syncronous requests). In case of asynchronous requests, all the
+requests from all the processes are batched together according to their
+process's I/O priority.
+
CFQ ioscheduler tunables
========================
controller or for storage arrays), setting slice_idle=0 might end up in better
throughput and acceptable latencies.
+back_seek_max
+-------------
+This specifies, given in Kbytes, the maximum "distance" for backward seeking.
+The distance is the amount of space from the current head location to the
+sectors that are backward in terms of distance.
+
+This parameter allows the scheduler to anticipate requests in the "backward"
+direction and consider them as being the "next" if they are within this
+distance from the current head location.
+
+back_seek_penalty
+-----------------
+This parameter is used to compute the cost of backward seeking. If the
+backward distance of request is just 1/back_seek_penalty from a "front"
+request, then the seeking cost of two requests is considered equivalent.
+
+So scheduler will not bias toward one or the other request (otherwise scheduler
+will bias toward front request). Default value of back_seek_penalty is 2.
+
+fifo_expire_async
+-----------------
+This parameter is used to set the timeout of asynchronous requests. Default
+value of this is 248ms.
+
+fifo_expire_sync
+----------------
+This parameter is used to set the timeout of synchronous requests. Default
+value of this is 124ms. In case to favor synchronous requests over asynchronous
+one, this value should be decreased relative to fifo_expire_async.
+
+slice_async
+-----------
+This parameter is same as of slice_sync but for asynchronous queue. The
+default value is 40ms.
+
+slice_async_rq
+--------------
+This parameter is used to limit the dispatching of asynchronous request to
+device request queue in queue's slice time. The maximum number of request that
+are allowed to be dispatched also depends upon the io priority. Default value
+for this is 2.
+
+slice_sync
+----------
+When a queue is selected for execution, the queues IO requests are only
+executed for a certain amount of time(time_slice) before switching to another
+queue. This parameter is used to calculate the time slice of synchronous
+queue.
+
+time_slice is computed using the below equation:-
+time_slice = slice_sync + (slice_sync/5 * (4 - prio)). To increase the
+time_slice of synchronous queue, increase the value of slice_sync. Default
+value is 100ms.
+
+quantum
+-------
+This specifies the number of request dispatched to the device queue. In a
+queue's time slice, a request will not be dispatched if the number of request
+in the device exceeds this parameter. This parameter is used for synchronous
+request.
+
+In case of storage with several disk, this setting can limit the parallel
+processing of request. Therefore, increasing the value can imporve the
+performace although this can cause the latency of some I/O to increase due
+to more number of requests.
+
CFQ IOPS Mode for group scheduling
===================================
Basic CFQ design is to provide priority based time slices. Higher priority
Files denoted with a RO postfix are readonly and the RW postfix means
read-write.
+add_random (RW)
+----------------
+This file allows to trun off the disk entropy contribution. Default
+value of this file is '1'(on).
+
+discard_granularity (RO)
+-----------------------
+This shows the size of internal allocation of the device in bytes, if
+reported by the device. A value of '0' means device does not support
+the discard functionality.
+
+discard_max_bytes (RO)
+----------------------
+Devices that support discard functionality may have internal limits on
+the number of bytes that can be trimmed or unmapped in a single operation.
+The discard_max_bytes parameter is set by the device driver to the maximum
+number of bytes that can be discarded in a single operation. Discard
+requests issued to the device must not exceed this limit. A discard_max_bytes
+value of 0 means that the device does not support discard functionality.
+
+discard_zeroes_data (RO)
+------------------------
+When read, this file will show if the discarded block are zeroed by the
+device or not. If its value is '1' the blocks are zeroed otherwise not.
+
hw_sector_size (RO)
-------------------
This is the hardware sector size of the device, in bytes.
+iostats (RW)
+-------------
+This file is used to control (on/off) the iostats accounting of the
+disk.
+
+logical_block_size (RO)
+-----------------------
+This is the logcal block size of the device, in bytes.
+
max_hw_sectors_kb (RO)
----------------------
This is the maximum number of kilobytes supported in a single data transfer.
+max_integrity_segments (RO)
+---------------------------
+When read, this file shows the max limit of integrity segments as
+set by block layer which a hardware controller can handle.
+
max_sectors_kb (RW)
-------------------
This is the maximum number of kilobytes that the block layer will allow
for a filesystem request. Must be smaller than or equal to the maximum
size allowed by the hardware.
+max_segments (RO)
+-----------------
+Maximum number of segments of the device.
+
+max_segment_size (RO)
+---------------------
+Maximum segment size of the device.
+
+minimum_io_size (RO)
+--------------------
+This is the smallest preferred io size reported by the device.
+
nomerges (RW)
-------------
This enables the user to disable the lookup logic involved with IO
each request queue may have upto N request pools, each independently
regulated by nr_requests.
+optimal_io_size (RO)
+--------------------
+This is the optimal io size reported by the device.
+
+physical_block_size (RO)
+------------------------
+This is the physical block size of device, in bytes.
+
read_ahead_kb (RW)
------------------
Maximum number of kilobytes to read-ahead for filesystems on this block
device.
+rotational (RW)
+---------------
+This file is used to stat if the device is of rotational type or
+non-rotational type.
+
rq_affinity (RW)
----------------
If this option is '1', the block layer will migrate request completions to the
struct request_queue *q = bdev_get_queue(bdev);
int type = REQ_WRITE | REQ_DISCARD;
unsigned int max_discard_sectors;
+ unsigned int granularity, alignment, mask;
struct bio_batch bb;
struct bio *bio;
int ret = 0;
if (!blk_queue_discard(q))
return -EOPNOTSUPP;
+ /* Zero-sector (unknown) and one-sector granularities are the same. */
+ granularity = max(q->limits.discard_granularity >> 9, 1U);
+ mask = granularity - 1;
+ alignment = (bdev_discard_alignment(bdev) >> 9) & mask;
+
/*
* Ensure that max_discard_sectors is of the proper
- * granularity
+ * granularity, so that requests stay aligned after a split.
*/
max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
+ max_discard_sectors = round_down(max_discard_sectors, granularity);
if (unlikely(!max_discard_sectors)) {
/* Avoid infinite loop below. Being cautious never hurts. */
return -EOPNOTSUPP;
- } else if (q->limits.discard_granularity) {
- unsigned int disc_sects = q->limits.discard_granularity >> 9;
-
- max_discard_sectors &= ~(disc_sects - 1);
}
if (flags & BLKDEV_DISCARD_SECURE) {
bb.wait = &wait;
while (nr_sects) {
+ unsigned int req_sects;
+ sector_t end_sect;
+
bio = bio_alloc(gfp_mask, 1);
if (!bio) {
ret = -ENOMEM;
break;
}
+ req_sects = min_t(sector_t, nr_sects, max_discard_sectors);
+
+ /*
+ * If splitting a request, and the next starting sector would be
+ * misaligned, stop the discard at the previous aligned sector.
+ */
+ end_sect = sector + req_sects;
+ if (req_sects < nr_sects && (end_sect & mask) != alignment) {
+ end_sect =
+ round_down(end_sect - alignment, granularity)
+ + alignment;
+ req_sects = end_sect - sector;
+ }
+
bio->bi_sector = sector;
bio->bi_end_io = bio_batch_end_io;
bio->bi_bdev = bdev;
bio->bi_private = &bb;
- if (nr_sects > max_discard_sectors) {
- bio->bi_size = max_discard_sectors << 9;
- nr_sects -= max_discard_sectors;
- sector += max_discard_sectors;
- } else {
- bio->bi_size = nr_sects << 9;
- nr_sects = 0;
- }
+ bio->bi_size = req_sects << 9;
+ nr_sects -= req_sects;
+ sector = end_sect;
atomic_inc(&bb.done);
submit_bio(type, bio);
return 0;
}
+static void
+__blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec,
+ struct scatterlist *sglist, struct bio_vec **bvprv,
+ struct scatterlist **sg, int *nsegs, int *cluster)
+{
+
+ int nbytes = bvec->bv_len;
+
+ if (*bvprv && *cluster) {
+ if ((*sg)->length + nbytes > queue_max_segment_size(q))
+ goto new_segment;
+
+ if (!BIOVEC_PHYS_MERGEABLE(*bvprv, bvec))
+ goto new_segment;
+ if (!BIOVEC_SEG_BOUNDARY(q, *bvprv, bvec))
+ goto new_segment;
+
+ (*sg)->length += nbytes;
+ } else {
+new_segment:
+ if (!*sg)
+ *sg = sglist;
+ else {
+ /*
+ * If the driver previously mapped a shorter
+ * list, we could see a termination bit
+ * prematurely unless it fully inits the sg
+ * table on each mapping. We KNOW that there
+ * must be more entries here or the driver
+ * would be buggy, so force clear the
+ * termination bit to avoid doing a full
+ * sg_init_table() in drivers for each command.
+ */
+ (*sg)->page_link &= ~0x02;
+ *sg = sg_next(*sg);
+ }
+
+ sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset);
+ (*nsegs)++;
+ }
+ *bvprv = bvec;
+}
+
/*
* map a request to scatterlist, return number of sg entries setup. Caller
* must make sure sg can hold rq->nr_phys_segments entries
bvprv = NULL;
sg = NULL;
rq_for_each_segment(bvec, rq, iter) {
- int nbytes = bvec->bv_len;
-
- if (bvprv && cluster) {
- if (sg->length + nbytes > queue_max_segment_size(q))
- goto new_segment;
-
- if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
- goto new_segment;
- if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
- goto new_segment;
-
- sg->length += nbytes;
- } else {
-new_segment:
- if (!sg)
- sg = sglist;
- else {
- /*
- * If the driver previously mapped a shorter
- * list, we could see a termination bit
- * prematurely unless it fully inits the sg
- * table on each mapping. We KNOW that there
- * must be more entries here or the driver
- * would be buggy, so force clear the
- * termination bit to avoid doing a full
- * sg_init_table() in drivers for each command.
- */
- sg->page_link &= ~0x02;
- sg = sg_next(sg);
- }
-
- sg_set_page(sg, bvec->bv_page, nbytes, bvec->bv_offset);
- nsegs++;
- }
- bvprv = bvec;
+ __blk_segment_map_sg(q, bvec, sglist, &bvprv, &sg,
+ &nsegs, &cluster);
} /* segments in rq */
}
EXPORT_SYMBOL(blk_rq_map_sg);
+/**
+ * blk_bio_map_sg - map a bio to a scatterlist
+ * @q: request_queue in question
+ * @bio: bio being mapped
+ * @sglist: scatterlist being mapped
+ *
+ * Note:
+ * Caller must make sure sg can hold bio->bi_phys_segments entries
+ *
+ * Will return the number of sg entries setup
+ */
+int blk_bio_map_sg(struct request_queue *q, struct bio *bio,
+ struct scatterlist *sglist)
+{
+ struct bio_vec *bvec, *bvprv;
+ struct scatterlist *sg;
+ int nsegs, cluster;
+ unsigned long i;
+
+ nsegs = 0;
+ cluster = blk_queue_cluster(q);
+
+ bvprv = NULL;
+ sg = NULL;
+ bio_for_each_segment(bvec, bio, i) {
+ __blk_segment_map_sg(q, bvec, sglist, &bvprv, &sg,
+ &nsegs, &cluster);
+ } /* segments in bio */
+
+ if (sg)
+ sg_mark_end(sg);
+
+ BUG_ON(bio->bi_phys_segments && nsegs > bio->bi_phys_segments);
+ return nsegs;
+}
+EXPORT_SYMBOL(blk_bio_map_sg);
+
static inline int ll_new_hw_segment(struct request_queue *q,
struct request *req,
struct bio *bio)
static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
{
- static void *p;
+ void *p;
p = disk_seqf_start(seqf, pos);
if (!IS_ERR_OR_NULL(p) && !*pos)
unsigned int done;
unsigned flags;
#define BM_AIO_COPY_PAGES 1
+#define BM_WRITE_ALL_PAGES 2
int error;
struct kref kref;
};
if (lazy_writeout_upper_idx && i == lazy_writeout_upper_idx)
break;
if (rw & WRITE) {
- if (bm_test_page_unchanged(b->bm_pages[i])) {
+ if (!(flags & BM_WRITE_ALL_PAGES) &&
+ bm_test_page_unchanged(b->bm_pages[i])) {
dynamic_dev_dbg(DEV, "skipped bm write for idx %u\n", i);
continue;
}
}
/**
+ * drbd_bm_write_all() - Write the whole bitmap to its on disk location.
+ * @mdev: DRBD device.
+ *
+ * Will write all pages.
+ */
+int drbd_bm_write_all(struct drbd_conf *mdev) __must_hold(local)
+{
+ return bm_rw(mdev, WRITE, BM_WRITE_ALL_PAGES, 0);
+}
+
+/**
* drbd_bm_lazy_write_out() - Write bitmap pages 0 to @upper_idx-1, if they have changed.
* @mdev: DRBD device.
* @upper_idx: 0: write all changed pages; +ve: page index to stop scanning for changed pages
extern int drbd_bm_write_page(struct drbd_conf *mdev, unsigned int idx) __must_hold(local);
extern int drbd_bm_read(struct drbd_conf *mdev) __must_hold(local);
extern int drbd_bm_write(struct drbd_conf *mdev) __must_hold(local);
+extern int drbd_bm_write_all(struct drbd_conf *mdev) __must_hold(local);
extern int drbd_bm_write_copy_pages(struct drbd_conf *mdev) __must_hold(local);
extern unsigned long drbd_bm_ALe_set_all(struct drbd_conf *mdev,
unsigned long al_enr);
static void md_sync_timer_fn(unsigned long data);
static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused);
static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused);
+static void _tl_clear(struct drbd_conf *mdev);
MODULE_AUTHOR("Philipp Reisner <phil@linbit.com>, "
"Lars Ellenberg <lars@linbit.com>");
/* Actions operating on the disk state, also want to work on
requests that got barrier acked. */
- switch (what) {
- case fail_frozen_disk_io:
- case restart_frozen_disk_io:
- list_for_each_safe(le, tle, &mdev->barrier_acked_requests) {
- req = list_entry(le, struct drbd_request, tl_requests);
- _req_mod(req, what);
- }
- case connection_lost_while_pending:
- case resend:
- break;
- default:
- dev_err(DEV, "what = %d in _tl_restart()\n", what);
+ list_for_each_safe(le, tle, &mdev->barrier_acked_requests) {
+ req = list_entry(le, struct drbd_request, tl_requests);
+ _req_mod(req, what);
}
}
*/
void tl_clear(struct drbd_conf *mdev)
{
+ spin_lock_irq(&mdev->req_lock);
+ _tl_clear(mdev);
+ spin_unlock_irq(&mdev->req_lock);
+}
+
+static void _tl_clear(struct drbd_conf *mdev)
+{
struct list_head *le, *tle;
struct drbd_request *r;
- spin_lock_irq(&mdev->req_lock);
-
_tl_restart(mdev, connection_lost_while_pending);
/* we expect this list to be empty. */
memset(mdev->app_reads_hash, 0, APP_R_HSIZE*sizeof(void *));
- spin_unlock_irq(&mdev->req_lock);
}
void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
if (ns.susp_fen) {
/* case1: The outdate peer handler is successful: */
if (os.pdsk > D_OUTDATED && ns.pdsk <= D_OUTDATED) {
- tl_clear(mdev);
if (test_bit(NEW_CUR_UUID, &mdev->flags)) {
drbd_uuid_new_current(mdev);
clear_bit(NEW_CUR_UUID, &mdev->flags);
}
spin_lock_irq(&mdev->req_lock);
+ _tl_clear(mdev);
_drbd_set_state(_NS(mdev, susp_fen, 0), CS_VERBOSE, NULL);
spin_unlock_irq(&mdev->req_lock);
}
la_size_changed && md_moved ? "size changed and md moved" :
la_size_changed ? "size changed" : "md moved");
/* next line implicitly does drbd_suspend_io()+drbd_resume_io() */
- err = drbd_bitmap_io(mdev, &drbd_bm_write,
- "size changed", BM_LOCKED_MASK);
+ err = drbd_bitmap_io(mdev, md_moved ? &drbd_bm_write_all : &drbd_bm_write,
+ "size changed", BM_LOCKED_MASK);
if (err) {
rv = dev_size_error;
goto out;
break;
case resend:
+ /* Simply complete (local only) READs. */
+ if (!(req->rq_state & RQ_WRITE) && !req->w.cb) {
+ _req_may_be_done(req, m);
+ break;
+ }
+
/* If RQ_NET_OK is already set, we got a P_WRITE_ACK or P_RECV_ACK
before the connection loss (B&C only); only P_BARRIER_ACK was missing.
Trowing them out of the TL here by pretending we got a BARRIER_ACK
req->private_bio = NULL;
}
if (rw == WRITE) {
- remote = 1;
+ /* Need to replicate writes. Unless it is an empty flush,
+ * which is better mapped to a DRBD P_BARRIER packet,
+ * also for drbd wire protocol compatibility reasons. */
+ if (unlikely(size == 0)) {
+ /* The only size==0 bios we expect are empty flushes. */
+ D_ASSERT(bio->bi_rw & REQ_FLUSH);
+ remote = 0;
+ } else
+ remote = 1;
} else {
/* READ || READA */
if (local) {
* extent. This waits for any resync activity in the corresponding
* resync extent to finish, and, if necessary, pulls in the target
* extent into the activity log, which involves further disk io because
- * of transactional on-disk meta data updates. */
- if (rw == WRITE && local && !test_bit(AL_SUSPENDED, &mdev->flags)) {
+ * of transactional on-disk meta data updates.
+ * Empty flushes don't need to go into the activity log, they can only
+ * flush data for pending writes which are already in there. */
+ if (rw == WRITE && local && size
+ && !test_bit(AL_SUSPENDED, &mdev->flags)) {
req->rq_state |= RQ_IN_ACT_LOG;
drbd_al_begin_io(mdev, sector);
}
if (rw == WRITE && _req_conflicts(req))
goto fail_conflicting;
- list_add_tail(&req->tl_requests, &mdev->newest_tle->requests);
+ /* no point in adding empty flushes to the transfer log,
+ * they are mapped to drbd barriers already. */
+ if (likely(size!=0))
+ list_add_tail(&req->tl_requests, &mdev->newest_tle->requests);
/* NOTE remote first: to get the concurrent write detection right,
* we must register the request before start of local IO. */
mdev->net_conf->on_congestion != OC_BLOCK && mdev->agreed_pro_version >= 96)
maybe_pull_ahead(mdev);
+ /* If this was a flush, queue a drbd barrier/start a new epoch.
+ * Unless the current epoch was empty anyways, or we are not currently
+ * replicating, in which case there is no point. */
+ if (unlikely(bio->bi_rw & REQ_FLUSH)
+ && mdev->newest_tle->n_writes
+ && drbd_should_do_remote(mdev->state))
+ queue_barrier(mdev);
+
spin_unlock_irq(&mdev->req_lock);
kfree(b); /* if someone else has beaten us to it... */
{
unsigned int sz = sizeof(struct bio) + extra_size;
struct kmem_cache *slab = NULL;
- struct bio_slab *bslab;
+ struct bio_slab *bslab, *new_bio_slabs;
unsigned int i, entry = -1;
mutex_lock(&bio_slab_lock);
if (bio_slab_nr == bio_slab_max && entry == -1) {
bio_slab_max <<= 1;
- bio_slabs = krealloc(bio_slabs,
- bio_slab_max * sizeof(struct bio_slab),
- GFP_KERNEL);
- if (!bio_slabs)
+ new_bio_slabs = krealloc(bio_slabs,
+ bio_slab_max * sizeof(struct bio_slab),
+ GFP_KERNEL);
+ if (!new_bio_slabs)
goto out_unlock;
+ bio_slabs = new_bio_slabs;
}
if (entry == -1)
entry = bio_slab_nr++;
unsigned long nr_segs, loff_t pos)
{
struct file *file = iocb->ki_filp;
+ struct blk_plug plug;
ssize_t ret;
BUG_ON(iocb->ki_pos != pos);
+ blk_start_plug(&plug);
ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
if (ret > 0 || ret == -EIOCBQUEUED) {
ssize_t err;
if (err < 0 && ret > 0)
ret = err;
}
+ blk_finish_plug(&plug);
return ret;
}
EXPORT_SYMBOL_GPL(blkdev_aio_write);
/*
* Initialise the state of a blockdev page's buffers.
*/
-static void
+static sector_t
init_page_buffers(struct page *page, struct block_device *bdev,
sector_t block, int size)
{
block++;
bh = bh->b_this_page;
} while (bh != head);
+
+ /*
+ * Caller needs to validate requested block against end of device.
+ */
+ return end_block;
}
/*
* Create the page-cache page that contains the requested block.
*
- * This is user purely for blockdev mappings.
+ * This is used purely for blockdev mappings.
*/
-static struct page *
+static int
grow_dev_page(struct block_device *bdev, sector_t block,
- pgoff_t index, int size)
+ pgoff_t index, int size, int sizebits)
{
struct inode *inode = bdev->bd_inode;
struct page *page;
struct buffer_head *bh;
+ sector_t end_block;
+ int ret = 0; /* Will call free_more_memory() */
page = find_or_create_page(inode->i_mapping, index,
(mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE);
if (!page)
- return NULL;
+ return ret;
BUG_ON(!PageLocked(page));
if (page_has_buffers(page)) {
bh = page_buffers(page);
if (bh->b_size == size) {
- init_page_buffers(page, bdev, block, size);
- return page;
+ end_block = init_page_buffers(page, bdev,
+ index << sizebits, size);
+ goto done;
}
if (!try_to_free_buffers(page))
goto failed;
*/
spin_lock(&inode->i_mapping->private_lock);
link_dev_buffers(page, bh);
- init_page_buffers(page, bdev, block, size);
+ end_block = init_page_buffers(page, bdev, index << sizebits, size);
spin_unlock(&inode->i_mapping->private_lock);
- return page;
-
+done:
+ ret = (block < end_block) ? 1 : -ENXIO;
failed:
unlock_page(page);
page_cache_release(page);
- return NULL;
+ return ret;
}
/*
static int
grow_buffers(struct block_device *bdev, sector_t block, int size)
{
- struct page *page;
pgoff_t index;
int sizebits;
bdevname(bdev, b));
return -EIO;
}
- block = index << sizebits;
+
/* Create a page with the proper size buffers.. */
- page = grow_dev_page(bdev, block, index, size);
- if (!page)
- return 0;
- unlock_page(page);
- page_cache_release(page);
- return 1;
+ return grow_dev_page(bdev, block, index, size, sizebits);
}
static struct buffer_head *
__getblk_slow(struct block_device *bdev, sector_t block, int size)
{
- int ret;
- struct buffer_head *bh;
-
/* Size must be multiple of hard sectorsize */
if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
(size < 512 || size > PAGE_SIZE))) {
return NULL;
}
-retry:
- bh = __find_get_block(bdev, block, size);
- if (bh)
- return bh;
+ for (;;) {
+ struct buffer_head *bh;
+ int ret;
- ret = grow_buffers(bdev, block, size);
- if (ret == 0) {
- free_more_memory();
- goto retry;
- } else if (ret > 0) {
bh = __find_get_block(bdev, block, size);
if (bh)
return bh;
+
+ ret = grow_buffers(bdev, block, size);
+ if (ret < 0)
+ return NULL;
+ if (ret == 0)
+ free_more_memory();
}
- return NULL;
}
/*
* which corresponds to the passed block_device, block and size. The
* returned buffer has its reference count incremented.
*
- * __getblk() cannot fail - it just keeps trying. If you pass it an
- * illegal block number, __getblk() will happily return a buffer_head
- * which represents the non-existent block. Very weird.
- *
* __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
* attempt is failing. FIXME, perhaps?
*/
unsigned long user_addr;
size_t bytes;
struct buffer_head map_bh = { 0, };
+ struct blk_plug plug;
if (rw & WRITE)
rw = WRITE_ODIRECT;
PAGE_SIZE - user_addr / PAGE_SIZE);
}
+ blk_start_plug(&plug);
+
for (seg = 0; seg < nr_segs; seg++) {
user_addr = (unsigned long)iov[seg].iov_base;
sdio.size += bytes = iov[seg].iov_len;
if (sdio.bio)
dio_bio_submit(dio, &sdio);
+ blk_finish_plug(&plug);
+
/*
* It is possible that, we return short IO due to end of file.
* In that case, we need to release all the pages we got hold on.
* it already be started by driver.
*/
#define RQ_NOMERGE_FLAGS \
- (REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA)
+ (REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA | REQ_DISCARD)
#define rq_mergeable(rq) \
(!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && \
(((rq)->cmd_flags & REQ_DISCARD) || \
extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
+extern int blk_bio_map_sg(struct request_queue *q, struct bio *bio,
+ struct scatterlist *sglist);
extern void blk_dump_rq_flags(struct request *, char *);
extern long nr_blockdev_pages(void);
& (lim->discard_granularity - 1);
}
+static inline int bdev_discard_alignment(struct block_device *bdev)
+{
+ struct request_queue *q = bdev_get_queue(bdev);
+
+ if (bdev != bdev->bd_contains)
+ return bdev->bd_part->discard_alignment;
+
+ return q->limits.discard_alignment;
+}
+
static inline unsigned int queue_discard_zeroes_data(struct request_queue *q)
{
if (q->limits.max_discard_sectors && q->limits.discard_zeroes_data == 1)
retval = filemap_write_and_wait_range(mapping, pos,
pos + iov_length(iov, nr_segs) - 1);
if (!retval) {
- struct blk_plug plug;
-
- blk_start_plug(&plug);
retval = mapping->a_ops->direct_IO(READ, iocb,
iov, pos, nr_segs);
- blk_finish_plug(&plug);
}
if (retval > 0) {
*ppos = pos + retval;
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
- struct blk_plug plug;
ssize_t ret;
BUG_ON(iocb->ki_pos != pos);
sb_start_write(inode->i_sb);
mutex_lock(&inode->i_mutex);
- blk_start_plug(&plug);
ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
mutex_unlock(&inode->i_mutex);
if (err < 0 && ret > 0)
ret = err;
}
- blk_finish_plug(&plug);
sb_end_write(inode->i_sb);
return ret;
}
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