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authorLinus Torvalds <torvalds@linux-foundation.org>2012-08-01 20:02:41 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-08-01 20:02:41 +0400
commit8cf1a3fce0b95050b63d451c9d561da0da2aa4d6 (patch)
tree0dc7f93474c3be601a5893900db1418dfd60ba5d /include/linux/genhd.h
parentfcff06c438b60f415af5983efe92811d6aa02ad1 (diff)
parent80799fbb7d10c30df78015b3fa21f7ffcfc0eb2c (diff)
downloadlinux-8cf1a3fce0b95050b63d451c9d561da0da2aa4d6.tar.xz
Merge branch 'for-3.6/core' of git://git.kernel.dk/linux-block
Pull core block IO bits from Jens Axboe: "The most complicated part if this is the request allocation rework by Tejun, which has been queued up for a long time and has been in for-next ditto as well. There are a few commits from yesterday and today, mostly trivial and obvious fixes. So I'm pretty confident that it is sound. It's also smaller than usual." * 'for-3.6/core' of git://git.kernel.dk/linux-block: block: remove dead func declaration block: add partition resize function to blkpg ioctl block: uninitialized ioc->nr_tasks triggers WARN_ON block: do not artificially constrain max_sectors for stacking drivers blkcg: implement per-blkg request allocation block: prepare for multiple request_lists block: add q->nr_rqs[] and move q->rq.elvpriv to q->nr_rqs_elvpriv blkcg: inline bio_blkcg() and friends block: allocate io_context upfront block: refactor get_request[_wait]() block: drop custom queue draining used by scsi_transport_{iscsi|fc} mempool: add @gfp_mask to mempool_create_node() blkcg: make root blkcg allocation use %GFP_KERNEL blkcg: __blkg_lookup_create() doesn't need radix preload
Diffstat (limited to 'include/linux/genhd.h')
-rw-r--r--include/linux/genhd.h57
1 files changed, 57 insertions, 0 deletions
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index ae0aaa9d42fa..4f440b3e89fe 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -97,7 +97,13 @@ struct partition_meta_info {
struct hd_struct {
sector_t start_sect;
+ /*
+ * nr_sects is protected by sequence counter. One might extend a
+ * partition while IO is happening to it and update of nr_sects
+ * can be non-atomic on 32bit machines with 64bit sector_t.
+ */
sector_t nr_sects;
+ seqcount_t nr_sects_seq;
sector_t alignment_offset;
unsigned int discard_alignment;
struct device __dev;
@@ -647,6 +653,57 @@ static inline void hd_struct_put(struct hd_struct *part)
__delete_partition(part);
}
+/*
+ * Any access of part->nr_sects which is not protected by partition
+ * bd_mutex or gendisk bdev bd_mutex, should be done using this
+ * accessor function.
+ *
+ * Code written along the lines of i_size_read() and i_size_write().
+ * CONFIG_PREEMPT case optimizes the case of UP kernel with preemption
+ * on.
+ */
+static inline sector_t part_nr_sects_read(struct hd_struct *part)
+{
+#if BITS_PER_LONG==32 && defined(CONFIG_LBDAF) && defined(CONFIG_SMP)
+ sector_t nr_sects;
+ unsigned seq;
+ do {
+ seq = read_seqcount_begin(&part->nr_sects_seq);
+ nr_sects = part->nr_sects;
+ } while (read_seqcount_retry(&part->nr_sects_seq, seq));
+ return nr_sects;
+#elif BITS_PER_LONG==32 && defined(CONFIG_LBDAF) && defined(CONFIG_PREEMPT)
+ sector_t nr_sects;
+
+ preempt_disable();
+ nr_sects = part->nr_sects;
+ preempt_enable();
+ return nr_sects;
+#else
+ return part->nr_sects;
+#endif
+}
+
+/*
+ * Should be called with mutex lock held (typically bd_mutex) of partition
+ * to provide mutual exlusion among writers otherwise seqcount might be
+ * left in wrong state leaving the readers spinning infinitely.
+ */
+static inline void part_nr_sects_write(struct hd_struct *part, sector_t size)
+{
+#if BITS_PER_LONG==32 && defined(CONFIG_LBDAF) && defined(CONFIG_SMP)
+ write_seqcount_begin(&part->nr_sects_seq);
+ part->nr_sects = size;
+ write_seqcount_end(&part->nr_sects_seq);
+#elif BITS_PER_LONG==32 && defined(CONFIG_LBDAF) && defined(CONFIG_PREEMPT)
+ preempt_disable();
+ part->nr_sects = size;
+ preempt_enable();
+#else
+ part->nr_sects = size;
+#endif
+}
+
#else /* CONFIG_BLOCK */
static inline void printk_all_partitions(void) { }