drivers/md/raid5-cache.c

Source file repositories/reference/linux-study-clean/drivers/md/raid5-cache.c

File Facts

System
Linux kernel
Corpus path
drivers/md/raid5-cache.c
Extension
.c
Size
89924 bytes
Lines
3188
Domain
Driver Families
Bucket
drivers/md
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct r5l_log {
	struct md_rdev *rdev;

	u32 uuid_checksum;

	sector_t device_size;		/* log device size, round to
					 * BLOCK_SECTORS */
	sector_t max_free_space;	/* reclaim run if free space is at
					 * this size */

	sector_t last_checkpoint;	/* log tail. where recovery scan
					 * starts from */
	u64 last_cp_seq;		/* log tail sequence */

	sector_t log_start;		/* log head. where new data appends */
	u64 seq;			/* log head sequence */

	sector_t next_checkpoint;

	struct mutex io_mutex;
	struct r5l_io_unit *current_io;	/* current io_unit accepting new data */

	spinlock_t io_list_lock;
	struct list_head running_ios;	/* io_units which are still running,
					 * and have not yet been completely
					 * written to the log */
	struct list_head io_end_ios;	/* io_units which have been completely
					 * written to the log but not yet written
					 * to the RAID */
	struct list_head flushing_ios;	/* io_units which are waiting for log
					 * cache flush */
	struct list_head finished_ios;	/* io_units which settle down in log disk */
	struct bio flush_bio;

	struct list_head no_mem_stripes;   /* pending stripes, -ENOMEM */

	struct kmem_cache *io_kc;
	mempool_t io_pool;
	struct bio_set bs;
	mempool_t meta_pool;

	struct md_thread __rcu *reclaim_thread;
	unsigned long reclaim_target;	/* number of space that need to be
					 * reclaimed.  if it's 0, reclaim spaces
					 * used by io_units which are in
					 * IO_UNIT_STRIPE_END state (eg, reclaim
					 * doesn't wait for specific io_unit
					 * switching to IO_UNIT_STRIPE_END
					 * state) */
	wait_queue_head_t iounit_wait;

	struct list_head no_space_stripes; /* pending stripes, log has no space */
	spinlock_t no_space_stripes_lock;

	bool need_cache_flush;

	/* for r5c_cache */
	enum r5c_journal_mode r5c_journal_mode;

	/* all stripes in r5cache, in the order of seq at sh->log_start */
	struct list_head stripe_in_journal_list;

	spinlock_t stripe_in_journal_lock;
	atomic_t stripe_in_journal_count;

	/* to submit async io_units, to fulfill ordering of flush */
	struct work_struct deferred_io_work;
	/* to disable write back during in degraded mode */
	struct work_struct disable_writeback_work;

	/* to for chunk_aligned_read in writeback mode, details below */
	spinlock_t tree_lock;
	struct radix_tree_root big_stripe_tree;
};

/*
 * Enable chunk_aligned_read() with write back cache.
 *
 * Each chunk may contain more than one stripe (for example, a 256kB
 * chunk contains 64 4kB-page, so this chunk contain 64 stripes). For
 * chunk_aligned_read, these stripes are grouped into one "big_stripe".
 * For each big_stripe, we count how many stripes of this big_stripe
 * are in the write back cache. These data are tracked in a radix tree
 * (big_stripe_tree). We use radix_tree item pointer as the counter.
 * r5c_tree_index() is used to calculate keys for the radix tree.
 *
 * chunk_aligned_read() calls r5c_big_stripe_cached() to look up
 * big_stripe of each chunk in the tree. If this big_stripe is in the
 * tree, chunk_aligned_read() aborts. This look up is protected by
 * rcu_read_lock().

Annotation

Implementation Notes