cregit-Linux how code gets into the kernel

Release 4.14 drivers/md/dm-bufio.c

Directory: drivers/md
/*
 * Copyright (C) 2009-2011 Red Hat, Inc.
 *
 * Author: Mikulas Patocka <mpatocka@redhat.com>
 *
 * This file is released under the GPL.
 */

#include "dm-bufio.h"

#include <linux/device-mapper.h>
#include <linux/dm-io.h>
#include <linux/slab.h>
#include <linux/sched/mm.h>
#include <linux/jiffies.h>
#include <linux/vmalloc.h>
#include <linux/shrinker.h>
#include <linux/module.h>
#include <linux/rbtree.h>
#include <linux/stacktrace.h>


#define DM_MSG_PREFIX "bufio"

/*
 * Memory management policy:
 *      Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory
 *      or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower).
 *      Always allocate at least DM_BUFIO_MIN_BUFFERS buffers.
 *      Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT
 *      dirty buffers.
 */

#define DM_BUFIO_MIN_BUFFERS		8


#define DM_BUFIO_MEMORY_PERCENT		2

#define DM_BUFIO_VMALLOC_PERCENT	25

#define DM_BUFIO_WRITEBACK_PERCENT	75

/*
 * Check buffer ages in this interval (seconds)
 */

#define DM_BUFIO_WORK_TIMER_SECS	30

/*
 * Free buffers when they are older than this (seconds)
 */

#define DM_BUFIO_DEFAULT_AGE_SECS	300

/*
 * The nr of bytes of cached data to keep around.
 */

#define DM_BUFIO_DEFAULT_RETAIN_BYTES   (256 * 1024)

/*
 * The number of bvec entries that are embedded directly in the buffer.
 * If the chunk size is larger, dm-io is used to do the io.
 */

#define DM_BUFIO_INLINE_VECS		16

/*
 * Don't try to use kmem_cache_alloc for blocks larger than this.
 * For explanation, see alloc_buffer_data below.
 */

#define DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT	(PAGE_SIZE >> 1)

#define DM_BUFIO_BLOCK_SIZE_GFP_LIMIT	(PAGE_SIZE << (MAX_ORDER - 1))

/*
 * Align buffer writes to this boundary.
 * Tests show that SSDs have the highest IOPS when using 4k writes.
 */

#define DM_BUFIO_WRITE_ALIGN		4096

/*
 * dm_buffer->list_mode
 */

#define LIST_CLEAN	0

#define LIST_DIRTY	1

#define LIST_SIZE	2

/*
 * Linking of buffers:
 *      All buffers are linked to cache_hash with their hash_list field.
 *
 *      Clean buffers that are not being written (B_WRITING not set)
 *      are linked to lru[LIST_CLEAN] with their lru_list field.
 *
 *      Dirty and clean buffers that are being written are linked to
 *      lru[LIST_DIRTY] with their lru_list field. When the write
 *      finishes, the buffer cannot be relinked immediately (because we
 *      are in an interrupt context and relinking requires process
 *      context), so some clean-not-writing buffers can be held on
 *      dirty_lru too.  They are later added to lru in the process
 *      context.
 */

struct dm_bufio_client {
	
struct mutex lock;

	
struct list_head lru[LIST_SIZE];
	
unsigned long n_buffers[LIST_SIZE];

	
struct block_device *bdev;
	
unsigned block_size;
	
unsigned char sectors_per_block_bits;
	
unsigned char pages_per_block_bits;
	
unsigned char blocks_per_page_bits;
	
unsigned aux_size;
	
void (*alloc_callback)(struct dm_buffer *);
	
void (*write_callback)(struct dm_buffer *);

	
struct dm_io_client *dm_io;

	
struct list_head reserved_buffers;
	
unsigned need_reserved_buffers;

	
unsigned minimum_buffers;

	
struct rb_root buffer_tree;
	
wait_queue_head_t free_buffer_wait;

	
sector_t start;

	
int async_write_error;

	
struct list_head client_list;
	
struct shrinker shrinker;
};

/*
 * Buffer state bits.
 */

#define B_READING	0

#define B_WRITING	1

#define B_DIRTY		2

/*
 * Describes how the block was allocated:
 * kmem_cache_alloc(), __get_free_pages() or vmalloc().
 * See the comment at alloc_buffer_data.
 */

enum data_mode {
	
DATA_MODE_SLAB = 0,
	
DATA_MODE_GET_FREE_PAGES = 1,
	
DATA_MODE_VMALLOC = 2,
	
DATA_MODE_LIMIT = 3
};


struct dm_buffer {
	
struct rb_node node;
	
struct list_head lru_list;
	
sector_t block;
	
void *data;
	
enum data_mode data_mode;
	
unsigned char list_mode;		/* LIST_* */
	
unsigned hold_count;
	
blk_status_t read_error;
	
blk_status_t write_error;
	
unsigned long state;
	
unsigned long last_accessed;
	
unsigned dirty_start;
	
unsigned dirty_end;
	
unsigned write_start;
	
unsigned write_end;
	
struct dm_bufio_client *c;
	
struct list_head write_list;
	
struct bio bio;
	
struct bio_vec bio_vec[DM_BUFIO_INLINE_VECS];
#ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING

#define MAX_STACK 10
	
struct stack_trace stack_trace;
	
unsigned long stack_entries[MAX_STACK];
#endif
};

/*----------------------------------------------------------------*/


static struct kmem_cache *dm_bufio_caches[PAGE_SHIFT - SECTOR_SHIFT];

static char *dm_bufio_cache_names[PAGE_SHIFT - SECTOR_SHIFT];


static inline int dm_bufio_cache_index(struct dm_bufio_client *c) { unsigned ret = c->blocks_per_page_bits - 1; BUG_ON(ret >= ARRAY_SIZE(dm_bufio_caches)); return ret; }

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#define DM_BUFIO_CACHE(c) (dm_bufio_caches[dm_bufio_cache_index(c)]) #define DM_BUFIO_CACHE_NAME(c) (dm_bufio_cache_names[dm_bufio_cache_index(c)]) #define dm_bufio_in_request() (!!current->bio_list)
static void dm_bufio_lock(struct dm_bufio_client *c) { mutex_lock_nested(&c->lock, dm_bufio_in_request()); }

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static int dm_bufio_trylock(struct dm_bufio_client *c) { return mutex_trylock(&c->lock); }

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static void dm_bufio_unlock(struct dm_bufio_client *c) { mutex_unlock(&c->lock); }

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/*----------------------------------------------------------------*/ /* * Default cache size: available memory divided by the ratio. */ static unsigned long dm_bufio_default_cache_size; /* * Total cache size set by the user. */ static unsigned long dm_bufio_cache_size; /* * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change * at any time. If it disagrees, the user has changed cache size. */ static unsigned long dm_bufio_cache_size_latch; static DEFINE_SPINLOCK(param_spinlock); /* * Buffers are freed after this timeout */ static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS; static unsigned long dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES; static unsigned long dm_bufio_peak_allocated; static unsigned long dm_bufio_allocated_kmem_cache; static unsigned long dm_bufio_allocated_get_free_pages; static unsigned long dm_bufio_allocated_vmalloc; static unsigned long dm_bufio_current_allocated; /*----------------------------------------------------------------*/ /* * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count */ static unsigned long dm_bufio_cache_size_per_client; /* * The current number of clients. */ static int dm_bufio_client_count; /* * The list of all clients. */ static LIST_HEAD(dm_bufio_all_clients); /* * This mutex protects dm_bufio_cache_size_latch, * dm_bufio_cache_size_per_client and dm_bufio_client_count */ static DEFINE_MUTEX(dm_bufio_clients_lock); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
static void buffer_record_stack(struct dm_buffer *b) { b->stack_trace.nr_entries = 0; b->stack_trace.max_entries = MAX_STACK; b->stack_trace.entries = b->stack_entries; b->stack_trace.skip = 2; save_stack_trace(&b->stack_trace); }

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#endif /*---------------------------------------------------------------- * A red/black tree acts as an index for all the buffers. *--------------------------------------------------------------*/
static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block) { struct rb_node *n = c->buffer_tree.rb_node; struct dm_buffer *b; while (n) { b = container_of(n, struct dm_buffer, node); if (b->block == block) return b; n = (b->block < block) ? n->rb_left : n->rb_right; } return NULL; }

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static void __insert(struct dm_bufio_client *c, struct dm_buffer *b) { struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL; struct dm_buffer *found; while (*new) { found = container_of(*new, struct dm_buffer, node); if (found->block == b->block) { BUG_ON(found != b); return; } parent = *new; new = (found->block < b->block) ? &((*new)->rb_left) : &((*new)->rb_right); } rb_link_node(&b->node, parent, new); rb_insert_color(&b->node, &c->buffer_tree); }

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static void __remove(struct dm_bufio_client *c, struct dm_buffer *b) { rb_erase(&b->node, &c->buffer_tree); }

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/*----------------------------------------------------------------*/
static void adjust_total_allocated(enum data_mode data_mode, long diff) { static unsigned long * const class_ptr[DATA_MODE_LIMIT] = { &dm_bufio_allocated_kmem_cache, &dm_bufio_allocated_get_free_pages, &dm_bufio_allocated_vmalloc, }; spin_lock(&param_spinlock); *class_ptr[data_mode] += diff; dm_bufio_current_allocated += diff; if (dm_bufio_current_allocated > dm_bufio_peak_allocated) dm_bufio_peak_allocated = dm_bufio_current_allocated; spin_unlock(&param_spinlock); }

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/* * Change the number of clients and recalculate per-client limit. */
static void __cache_size_refresh(void) { BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock)); BUG_ON(dm_bufio_client_count < 0); dm_bufio_cache_size_latch = ACCESS_ONCE(dm_bufio_cache_size); /* * Use default if set to 0 and report the actual cache size used. */ if (!dm_bufio_cache_size_latch) { (void)cmpxchg(&dm_bufio_cache_size, 0, dm_bufio_default_cache_size); dm_bufio_cache_size_latch = dm_bufio_default_cache_size; } dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch / (dm_bufio_client_count ? : 1); }

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/* * Allocating buffer data. * * Small buffers are allocated with kmem_cache, to use space optimally. * * For large buffers, we choose between get_free_pages and vmalloc. * Each has advantages and disadvantages. * * __get_free_pages can randomly fail if the memory is fragmented. * __vmalloc won't randomly fail, but vmalloc space is limited (it may be * as low as 128M) so using it for caching is not appropriate. * * If the allocation may fail we use __get_free_pages. Memory fragmentation * won't have a fatal effect here, but it just causes flushes of some other * buffers and more I/O will be performed. Don't use __get_free_pages if it * always fails (i.e. order >= MAX_ORDER). * * If the allocation shouldn't fail we use __vmalloc. This is only for the * initial reserve allocation, so there's no risk of wasting all vmalloc * space. */
static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask, enum data_mode *data_mode) { unsigned noio_flag; void *ptr; if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) { *data_mode = DATA_MODE_SLAB; return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask); } if (c->block_size <= DM_BUFIO_BLOCK_SIZE_GFP_LIMIT && gfp_mask & __GFP_NORETRY) { *data_mode = DATA_MODE_GET_FREE_PAGES; return (void *)__get_free_pages(gfp_mask, c->pages_per_block_bits); } *data_mode = DATA_MODE_VMALLOC; /* * __vmalloc allocates the data pages and auxiliary structures with * gfp_flags that were specified, but pagetables are always allocated * with GFP_KERNEL, no matter what was specified as gfp_mask. * * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that * all allocations done by this process (including pagetables) are done * as if GFP_NOIO was specified. */ if (gfp_mask & __GFP_NORETRY) noio_flag = memalloc_noio_save(); ptr = __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL); if (gfp_mask & __GFP_NORETRY) memalloc_noio_restore(noio_flag); return ptr; }

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/* * Free buffer's data. */
static void free_buffer_data(struct dm_bufio_client *c, void *data, enum data_mode data_mode) { switch (data_mode) { case DATA_MODE_SLAB: kmem_cache_free(DM_BUFIO_CACHE(c), data); break; case DATA_MODE_GET_FREE_PAGES: free_pages((unsigned long)data, c->pages_per_block_bits); break; case DATA_MODE_VMALLOC: vfree(data); break; default: DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d", data_mode); BUG(); } }

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/* * Allocate buffer and its data. */
static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask) { struct dm_buffer *b = kmalloc(sizeof(struct dm_buffer) + c->aux_size, gfp_mask); if (!b) return NULL; b->c = c; b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode); if (!b->data) { kfree(b); return NULL; } adjust_total_allocated(b->data_mode, (long)c->block_size); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING memset(&b->stack_trace, 0, sizeof(b->stack_trace)); #endif return b; }

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/* * Free buffer and its data. */
static void free_buffer(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; adjust_total_allocated(b->data_mode, -(long)c->block_size); free_buffer_data(c, b->data, b->data_mode); kfree(b); }

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/* * Link buffer to the hash list and clean or dirty queue. */
static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty) { struct dm_bufio_client *c = b->c; c->n_buffers[dirty]++; b->block = block; b->list_mode = dirty; list_add(&b->lru_list, &c->lru[dirty]); __insert(b->c, b); b->last_accessed = jiffies; }

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/* * Unlink buffer from the hash list and dirty or clean queue. */
static void __unlink_buffer(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; BUG_ON(!c->n_buffers[b->list_mode]); c->n_buffers[b->list_mode]--; __remove(b->c, b); list_del(&b->lru_list); }

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/* * Place the buffer to the head of dirty or clean LRU queue. */
static void __relink_lru(struct dm_buffer *b, int dirty) { struct dm_bufio_client *c = b->c; BUG_ON(!c->n_buffers[b->list_mode]); c->n_buffers[b->list_mode]--; c->n_buffers[dirty]++; b->list_mode = dirty; list_move(&b->lru_list, &c->lru[dirty]); b->last_accessed = jiffies; }

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/*---------------------------------------------------------------- * Submit I/O on the buffer. * * Bio interface is faster but it has some problems: * the vector list is limited (increasing this limit increases * memory-consumption per buffer, so it is not viable); * * the memory must be direct-mapped, not vmalloced; * * the I/O driver can reject requests spuriously if it thinks that * the requests are too big for the device or if they cross a * controller-defined memory boundary. * * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and * it is not vmalloced, try using the bio interface. * * If the buffer is big, if it is vmalloced or if the underlying device * rejects the bio because it is too large, use dm-io layer to do the I/O. * The dm-io layer splits the I/O into multiple requests, avoiding the above * shortcomings. *--------------------------------------------------------------*/ /* * dm-io completion routine. It just calls b->bio.bi_end_io, pretending * that the request was handled directly with bio interface. */
static void dmio_complete(unsigned long error, void *context) { struct dm_buffer *b = context; b->bio.bi_status = error ? BLK_STS_IOERR : 0; b->bio.bi_end_io(&b->bio); }

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static void use_dmio(struct dm_buffer *b, int rw, sector_t sector, unsigned n_sectors, unsigned offset, bio_end_io_t *end_io) { int r; struct dm_io_request io_req = { .bi_op = rw, .bi_op_flags = 0, .notify.fn = dmio_complete, .notify.context = b, .client = b->c->dm_io, }; struct dm_io_region region = { .bdev = b->c->bdev, .sector = sector, .count = n_sectors, }; if (b->data_mode != DATA_MODE_VMALLOC) { io_req.mem.type = DM_IO_KMEM; io_req.mem.ptr.addr = (char *)b->data + offset; } else { io_req.mem.type = DM_IO_VMA; io_req.mem.ptr.vma = (char *)b->data + offset; } b->bio.bi_end_io = end_io; r = dm_io(&io_req, 1, &region, NULL); if (r) { b->bio.bi_status = errno_to_blk_status(r); end_io(&b->bio); } }

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static void inline_endio(struct bio *bio) { bio_end_io_t *end_fn = bio->bi_private; blk_status_t status = bio->bi_status; /* * Reset the bio to free any attached resources * (e.g. bio integrity profiles). */ bio_reset(bio); bio->bi_status = status; end_fn(bio); }

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static void use_inline_bio(struct dm_buffer *b, int rw, sector_t sector, unsigned n_sectors, unsigned offset, bio_end_io_t *end_io) { char *ptr; unsigned len; bio_init(&b->bio, b->bio_vec, DM_BUFIO_INLINE_VECS); b->bio.bi_iter.bi_sector = sector; bio_set_dev(&b->bio, b->c->bdev); b->bio.bi_end_io = inline_endio; /* * Use of .bi_private isn't a problem here because * the dm_buffer's inline bio is local to bufio. */ b->bio.bi_private = end_io; bio_set_op_attrs(&b->bio, rw, 0); ptr = (char *)b->data + offset; len = n_sectors << SECTOR_SHIFT; do { unsigned this_step = min((unsigned)(PAGE_SIZE - offset_in_page(ptr)), len); if (!bio_add_page(&b->bio, virt_to_page(ptr), this_step, offset_in_page(ptr))) { BUG_ON(b->c->block_size <= PAGE_SIZE); use_dmio(b, rw, sector, n_sectors, offset, end_io); return; } len -= this_step; ptr += this_step; } while (len > 0); submit_bio(&b->bio); }

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Lei Ming31.38%110.00%
Kent Overstreet20.92%110.00%
Al Viro10.46%110.00%
Total217100.00%10100.00%


static void submit_io(struct dm_buffer *b, int rw, bio_end_io_t *end_io) { unsigned n_sectors; sector_t sector; unsigned offset, end; sector = (b->block << b->c->sectors_per_block_bits) + b->c->start; if (rw != WRITE) { n_sectors = 1 << b->c->sectors_per_block_bits; offset = 0; } else { if (b->c->write_callback) b->c->write_callback(b); offset = b->write_start; end = b->write_end; offset &= -DM_BUFIO_WRITE_ALIGN; end += DM_BUFIO_WRITE_ALIGN - 1; end &= -DM_BUFIO_WRITE_ALIGN; if (unlikely(end > b->c->block_size)) end = b->c->block_size; sector += offset >> SECTOR_SHIFT; n_sectors = (end - offset) >> SECTOR_SHIFT; } if (n_sectors <= ((DM_BUFIO_INLINE_VECS * PAGE_SIZE) >> SECTOR_SHIFT) && b->data_mode != DATA_MODE_VMALLOC) use_inline_bio(b, rw, sector, n_sectors, offset, end_io); else use_dmio(b, rw, sector, n_sectors, offset, end_io); }

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/*---------------------------------------------------------------- * Writing dirty buffers *--------------------------------------------------------------*/ /* * The endio routine for write. * * Set the error, clear B_WRITING bit and wake anyone who was waiting on * it. */
static void write_endio(struct bio *bio) { struct dm_buffer *b = container_of(bio, struct dm_buffer, bio); b->write_error = bio->bi_status; if (unlikely(bio->bi_status)) { struct dm_bufio_client *c = b->c; (void)cmpxchg(&c->async_write_error, 0, blk_status_to_errno(bio->bi_status)); } BUG_ON(!test_bit(B_WRITING, &b->state)); smp_mb__before_atomic(); clear_bit(B_WRITING, &b->state); smp_mb__after_atomic(); wake_up_bit(&b->state, B_WRITING); }

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/* * Initiate a write on a dirty buffer, but don't wait for it. * * - If the buffer is not dirty, exit. * - If there some previous write going on, wait for it to finish (we can't * have two writes on the same buffer simultaneously). * - Submit our write and don't wait on it. We set B_WRITING indicating * that there is a write in progress. */
static void __write_dirty_buffer(struct dm_buffer *b, struct list_head *write_list) { if (!test_bit(B_DIRTY, &b->state)) return; clear_bit(B_DIRTY, &b->state); wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); b->write_start = b->dirty_start; b->write_end = b->dirty_end; if (!write_list) submit_io(b, WRITE, write_endio); else list_add_tail(&b->write_list, write_list); }

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static void __flush_write_list(struct list_head *write_list) { struct blk_plug plug; blk_start_plug(&plug); while (!list_empty(write_list)) { struct dm_buffer *b = list_entry(write_list->next, struct dm_buffer, write_list); list_del(&b->write_list); submit_io(b, WRITE, write_endio); cond_resched(); } blk_finish_plug(&plug); }

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/* * Wait until any activity on the buffer finishes. Possibly write the * buffer if it is dirty. When this function finishes, there is no I/O * running on the buffer and the buffer is not dirty. */
static void __make_buffer_clean(struct dm_buffer *b) { BUG_ON(b->hold_count); if (!b->state) /* fast case */ return; wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); __write_dirty_buffer(b, NULL); wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); }

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Total58100.00%3100.00%

/* * Find some buffer that is not held by anybody, clean it, unlink it and * return it. */
static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c) { struct dm_buffer *b; list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) { BUG_ON(test_bit(B_WRITING, &b->state)); BUG_ON(test_bit(B_DIRTY, &b->state)); if (!b->hold_count) { __make_buffer_clean(b); __unlink_buffer(b); return b; } cond_resched(); } list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) { BUG_ON(test_bit(B_READING, &b->state)); if (!b->hold_count) { __make_buffer_clean(b); __unlink_buffer(b); return b; } cond_resched(); } return NULL; }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka12898.46%150.00%
Peter Zijlstra21.54%150.00%
Total130100.00%2100.00%

/* * Wait until some other threads free some buffer or release hold count on * some buffer. * * This function is entered with c->lock held, drops it and regains it * before exiting. */
static void __wait_for_free_buffer(struct dm_bufio_client *c) { DECLARE_WAITQUEUE(wait, current); add_wait_queue(&c->free_buffer_wait, &wait); set_current_state(TASK_UNINTERRUPTIBLE); dm_bufio_unlock(c); io_schedule(); remove_wait_queue(&c->free_buffer_wait, &wait); dm_bufio_lock(c); }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka5798.28%150.00%
Davidlohr Bueso A11.72%150.00%
Total58100.00%2100.00%

enum new_flag { NF_FRESH = 0, NF_READ = 1, NF_GET = 2, NF_PREFETCH = 3 }; /* * Allocate a new buffer. If the allocation is not possible, wait until * some other thread frees a buffer. * * May drop the lock and regain it. */
static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf) { struct dm_buffer *b; bool tried_noio_alloc = false; /* * dm-bufio is resistant to allocation failures (it just keeps * one buffer reserved in cases all the allocations fail). * So set flags to not try too hard: * GFP_NOWAIT: don't wait; if we need to sleep we'll release our * mutex and wait ourselves. * __GFP_NORETRY: don't retry and rather return failure * __GFP_NOMEMALLOC: don't use emergency reserves * __GFP_NOWARN: don't print a warning in case of failure * * For debugging, if we set the cache size to 1, no new buffers will * be allocated. */ while (1) { if (dm_bufio_cache_size_latch != 1) { b = alloc_buffer(c, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); if (b) return b; } if (nf == NF_PREFETCH) return NULL; if (dm_bufio_cache_size_latch != 1 && !tried_noio_alloc) { dm_bufio_unlock(c); b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); dm_bufio_lock(c); if (b) return b; tried_noio_alloc = true; } if (!list_empty(&c->reserved_buffers)) { b = list_entry(c->reserved_buffers.next, struct dm_buffer, lru_list); list_del(&b->lru_list); c->need_reserved_buffers++; return b; } b = __get_unclaimed_buffer(c); if (b) return b; __wait_for_free_buffer(c); } }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka18298.91%375.00%
Douglas Anderson21.09%125.00%
Total184100.00%4100.00%


static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf) { struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf); if (!b) return NULL; if (c->alloc_callback) c->alloc_callback(b); return b; }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka53100.00%2100.00%
Total53100.00%2100.00%

/* * Free a buffer and wake other threads waiting for free buffers. */
static void __free_buffer_wake(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; if (!c->need_reserved_buffers) free_buffer(b); else { list_add(&b->lru_list, &c->reserved_buffers); c->need_reserved_buffers--; } wake_up(&c->free_buffer_wait); }

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Mikulas Patocka61100.00%1100.00%
Total61100.00%1100.00%


static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait, struct list_head *write_list) { struct dm_buffer *b, *tmp; list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { BUG_ON(test_bit(B_READING, &b->state)); if (!test_bit(B_DIRTY, &b->state) && !test_bit(B_WRITING, &b->state)) { __relink_lru(b, LIST_CLEAN); continue; } if (no_wait && test_bit(B_WRITING, &b->state)) return; __write_dirty_buffer(b, write_list); cond_resched(); } }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka11099.10%266.67%
Peter Zijlstra10.90%133.33%
Total111100.00%3100.00%

/* * Get writeback threshold and buffer limit for a given client. */
static void __get_memory_limit(struct dm_bufio_client *c, unsigned long *threshold_buffers, unsigned long *limit_buffers) { unsigned long buffers; if (unlikely(ACCESS_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch)) { if (mutex_trylock(&dm_bufio_clients_lock)) { __cache_size_refresh(); mutex_unlock(&dm_bufio_clients_lock); } } buffers = dm_bufio_cache_size_per_client >> (c->sectors_per_block_bits + SECTOR_SHIFT); if (buffers < c->minimum_buffers) buffers = c->minimum_buffers; *limit_buffers = buffers; *threshold_buffers = buffers * DM_BUFIO_WRITEBACK_PERCENT / 100; }

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Mikulas Patocka98100.00%4100.00%
Total98100.00%4100.00%

/* * Check if we're over watermark. * If we are over threshold_buffers, start freeing buffers. * If we're over "limit_buffers", block until we get under the limit. */
static void __check_watermark(struct dm_bufio_client *c, struct list_head *write_list) { unsigned long threshold_buffers, limit_buffers; __get_memory_limit(c, &threshold_buffers, &limit_buffers); while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] > limit_buffers) { struct dm_buffer *b = __get_unclaimed_buffer(c); if (!b) return; __free_buffer_wake(b); cond_resched(); } if (c->n_buffers[LIST_DIRTY] > threshold_buffers) __write_dirty_buffers_async(c, 1, write_list); }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka9698.97%266.67%
Peter Zijlstra11.03%133.33%
Total97100.00%3100.00%

/*---------------------------------------------------------------- * Getting a buffer *--------------------------------------------------------------*/
static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, enum new_flag nf, int *need_submit, struct list_head *write_list) { struct dm_buffer *b, *new_b = NULL; *need_submit = 0; b = __find(c, block); if (b) goto found_buffer; if (nf == NF_GET) return NULL; new_b = __alloc_buffer_wait(c, nf); if (!new_b) return NULL; /* * We've had a period where the mutex was unlocked, so need to * recheck the hash table. */ b = __find(c, block); if (b) { __free_buffer_wake(new_b); goto found_buffer; } __check_watermark(c, write_list); b = new_b; b->hold_count = 1; b->read_error = 0; b->write_error = 0; __link_buffer(b, block, LIST_CLEAN); if (nf == NF_FRESH) { b->state = 0; return b; } b->state = 1 << B_READING; *need_submit = 1; return b; found_buffer: if (nf == NF_PREFETCH) return NULL; /* * Note: it is essential that we don't wait for the buffer to be * read if dm_bufio_get function is used. Both dm_bufio_get and * dm_bufio_prefetch can be used in the driver request routine. * If the user called both dm_bufio_prefetch and dm_bufio_get on * the same buffer, it would deadlock if we waited. */ if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state))) return NULL; b->hold_count++; __relink_lru(b, test_bit(B_DIRTY, &b->state) || test_bit(B_WRITING, &b->state)); return b; }

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Mikulas Patocka248100.00%3100.00%
Total248100.00%3100.00%

/* * The endio routine for reading: set the error, clear the bit and wake up * anyone waiting on the buffer. */
static void read_endio(struct bio *bio) { struct dm_buffer *b = container_of(bio, struct dm_buffer, bio); b->read_error = bio->bi_status; BUG_ON(!test_bit(B_READING, &b->state)); smp_mb__before_atomic(); clear_bit(B_READING, &b->state); smp_mb__after_atomic(); wake_up_bit(&b->state, B_READING); }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka6993.24%125.00%
Christoph Hellwig34.05%250.00%
Peter Zijlstra22.70%125.00%
Total74100.00%4100.00%

/* * A common routine for dm_bufio_new and dm_bufio_read. Operation of these * functions is similar except that dm_bufio_new doesn't read the * buffer from the disk (assuming that the caller overwrites all the data * and uses dm_bufio_mark_buffer_dirty to write new data back). */
static void *new_read(struct dm_bufio_client *c, sector_t block, enum new_flag nf, struct dm_buffer **bp) { int need_submit; struct dm_buffer *b; LIST_HEAD(write_list); dm_bufio_lock(c); b = __bufio_new(c, block, nf, &need_submit, &write_list); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING if (b && b->hold_count == 1) buffer_record_stack(b); #endif dm_bufio_unlock(c); __flush_write_list(&write_list); if (!b) return NULL; if (need_submit) submit_io(b, READ, read_endio); wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); if (b->read_error) { int error = blk_status_to_errno(b->read_error); dm_bufio_release(b); return ERR_PTR(error); } *bp = b; return b->data; }

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Mikulas Patocka15997.55%466.67%
Christoph Hellwig31.84%116.67%
Neil Brown10.61%116.67%
Total163100.00%6100.00%


void *dm_bufio_get(struct dm_bufio_client *c, sector_t block, struct dm_buffer **bp) { return new_read(c, block, NF_GET, bp); }

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Mikulas Patocka32100.00%1100.00%
Total32100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_get);
void *dm_bufio_read(struct dm_bufio_client *c, sector_t block, struct dm_buffer **bp) { BUG_ON(dm_bufio_in_request()); return new_read(c, block, NF_READ, bp); }

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Mikulas Patocka38100.00%1100.00%
Total38100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_read);
void *dm_bufio_new(struct dm_bufio_client *c, sector_t block, struct dm_buffer **bp) { BUG_ON(dm_bufio_in_request()); return new_read(c, block, NF_FRESH, bp); }

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Mikulas Patocka38100.00%1100.00%
Total38100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_new);
void dm_bufio_prefetch(struct dm_bufio_client *c, sector_t block, unsigned n_blocks) { struct blk_plug plug; LIST_HEAD(write_list); BUG_ON(dm_bufio_in_request()); blk_start_plug(&plug); dm_bufio_lock(c); for (; n_blocks--; block++) { int need_submit; struct dm_buffer *b; b = __bufio_new(c, block, NF_PREFETCH, &need_submit, &write_list); if (unlikely(!list_empty(&write_list))) { dm_bufio_unlock(c); blk_finish_plug(&plug); __flush_write_list(&write_list); blk_start_plug(&plug); dm_bufio_lock(c); } if (unlikely(b != NULL)) { dm_bufio_unlock(c); if (need_submit) submit_io(b, READ, read_endio); dm_bufio_release(b); cond_resched(); if (!n_blocks) goto flush_plug; dm_bufio_lock(c); } } dm_bufio_unlock(c); flush_plug: blk_finish_plug(&plug); }

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Mikulas Patocka18299.45%375.00%
Peter Zijlstra10.55%125.00%
Total183100.00%4100.00%

EXPORT_SYMBOL_GPL(dm_bufio_prefetch);
void dm_bufio_release(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; dm_bufio_lock(c); BUG_ON(!b->hold_count); b->hold_count--; if (!b->hold_count) { wake_up(&c->free_buffer_wait); /* * If there were errors on the buffer, and the buffer is not * to be written, free the buffer. There is no point in caching * invalid buffer. */ if ((b->read_error || b->write_error) && !test_bit(B_READING, &b->state) && !test_bit(B_WRITING, &b->state) && !test_bit(B_DIRTY, &b->state)) { __unlink_buffer(b); __free_buffer_wake(b); } } dm_bufio_unlock(c); }

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Mikulas Patocka117100.00%2100.00%
Total117100.00%2100.00%

EXPORT_SYMBOL_GPL(dm_bufio_release);
void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b, unsigned start, unsigned end) { struct dm_bufio_client *c = b->c; BUG_ON(start >= end); BUG_ON(end > b->c->block_size); dm_bufio_lock(c); BUG_ON(test_bit(B_READING, &b->state)); if (!test_and_set_bit(B_DIRTY, &b->state)) { b->dirty_start = start; b->dirty_end = end; __relink_lru(b, LIST_DIRTY); } else { if (start < b->dirty_start) b->dirty_start = start; if (end > b->dirty_end) b->dirty_end = end; } dm_bufio_unlock(c); }

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Mikulas Patocka131100.00%3100.00%
Total131100.00%3100.00%

EXPORT_SYMBOL_GPL(dm_bufio_mark_partial_buffer_dirty);
void dm_bufio_mark_buffer_dirty(struct dm_buffer *b) { dm_bufio_mark_partial_buffer_dirty(b, 0, b->c->block_size); }

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Mikulas Patocka23100.00%1100.00%
Total23100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty);
void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c) { LIST_HEAD(write_list); BUG_ON(dm_bufio_in_request()); dm_bufio_lock(c); __write_dirty_buffers_async(c, 0, &write_list); dm_bufio_unlock(c); __flush_write_list(&write_list); }

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Mikulas Patocka47100.00%2100.00%
Total47100.00%2100.00%

EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async); /* * For performance, it is essential that the buffers are written asynchronously * and simultaneously (so that the block layer can merge the writes) and then * waited upon. * * Finally, we flush hardware disk cache. */
int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c) { int a, f; unsigned long buffers_processed = 0; struct dm_buffer *b, *tmp; LIST_HEAD(write_list); dm_bufio_lock(c); __write_dirty_buffers_async(c, 0, &write_list); dm_bufio_unlock(c); __flush_write_list(&write_list); dm_bufio_lock(c); again: list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { int dropped_lock = 0; if (buffers_processed < c->n_buffers[LIST_DIRTY]) buffers_processed++; BUG_ON(test_bit(B_READING, &b->state)); if (test_bit(B_WRITING, &b->state)) { if (buffers_processed < c->n_buffers[LIST_DIRTY]) { dropped_lock = 1; b->hold_count++; dm_bufio_unlock(c); wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); dm_bufio_lock(c); b->hold_count--; } else wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); } if (!test_bit(B_DIRTY, &b->state) && !test_bit(B_WRITING, &b->state)) __relink_lru(b, LIST_CLEAN); cond_resched(); /* * If we dropped the lock, the list is no longer consistent, * so we must restart the search. * * In the most common case, the buffer just processed is * relinked to the clean list, so we won't loop scanning the * same buffer again and again. * * This may livelock if there is another thread simultaneously * dirtying buffers, so we count the number of buffers walked * and if it exceeds the total number of buffers, it means that * someone is doing some writes simultaneously with us. In * this case, stop, dropping the lock. */ if (dropped_lock) goto again; } wake_up(&c->free_buffer_wait); dm_bufio_unlock(c); a = xchg(&c->async_write_error, 0); f = dm_bufio_issue_flush(c); if (a) return a; return f; }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka26597.79%233.33%
Dan Carpenter20.74%116.67%
Neil Brown20.74%116.67%
Peter Zijlstra10.37%116.67%
Christoph Hellwig10.37%116.67%
Total271100.00%6100.00%

EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers); /* * Use dm-io to send and empty barrier flush the device. */
int dm_bufio_issue_flush(struct dm_bufio_client *c) { struct dm_io_request io_req = { .bi_op = REQ_OP_WRITE, .bi_op_flags = REQ_PREFLUSH | REQ_SYNC, .mem.type = DM_IO_KMEM, .mem.ptr.addr = NULL, .client = c->dm_io, }; struct dm_io_region io_reg = { .bdev = c->bdev, .sector = 0, .count = 0, }; BUG_ON(dm_bufio_in_request()); return dm_io(&io_req, 1, &io_reg, NULL); }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka8590.43%125.00%
Michael Christie66.38%125.00%
Jan Kara22.13%125.00%
Christoph Hellwig11.06%125.00%
Total94100.00%4100.00%

EXPORT_SYMBOL_GPL(dm_bufio_issue_flush); /* * We first delete any other buffer that may be at that new location. * * Then, we write the buffer to the original location if it was dirty. * * Then, if we are the only one who is holding the buffer, relink the buffer * in the hash queue for the new location. * * If there was someone else holding the buffer, we write it to the new * location but not relink it, because that other user needs to have the buffer * at the same place. */
void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block) { struct dm_bufio_client *c = b->c; struct dm_buffer *new; BUG_ON(dm_bufio_in_request()); dm_bufio_lock(c); retry: new = __find(c, new_block); if (new) { if (new->hold_count) { __wait_for_free_buffer(c); goto retry; } /* * FIXME: Is there any point waiting for a write that's going * to be overwritten in a bit? */ __make_buffer_clean(new); __unlink_buffer(new); __free_buffer_wake(new); } BUG_ON(!b->hold_count); BUG_ON(test_bit(B_READING, &b->state)); __write_dirty_buffer(b, NULL); if (b->hold_count == 1) { wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); set_bit(B_DIRTY, &b->state); b->dirty_start = 0; b->dirty_end = c->block_size; __unlink_buffer(b); __link_buffer(b, new_block, LIST_DIRTY); } else { sector_t old_block; wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); /* * Relink buffer to "new_block" so that write_callback * sees "new_block" as a block number. * After the write, link the buffer back to old_block. * All this must be done in bufio lock, so that block number * change isn't visible to other threads. */ old_block = b->block; __unlink_buffer(b); __link_buffer(b, new_block, b->list_mode); submit_io(b, WRITE, write_endio); wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); __unlink_buffer(b); __link_buffer(b, old_block, b->list_mode); } dm_bufio_unlock(c); dm_bufio_release(b); }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka26098.86%375.00%
Neil Brown31.14%125.00%
Total263100.00%4100.00%

EXPORT_SYMBOL_GPL(dm_bufio_release_move); /* * Free the given buffer. * * This is just a hint, if the buffer is in use or dirty, this function * does nothing. */
void dm_bufio_forget(struct dm_bufio_client *c, sector_t block) { struct dm_buffer *b; dm_bufio_lock(c); b = __find(c, block); if (b && likely(!b->hold_count) && likely(!b->state)) { __unlink_buffer(b); __free_buffer_wake(b); } dm_bufio_unlock(c); }

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Mikulas Patocka69100.00%1100.00%
Total69100.00%1100.00%

EXPORT_SYMBOL(dm_bufio_forget);
void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n) { c->minimum_buffers = n; }

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Mikulas Patocka19100.00%1100.00%
Total19100.00%1100.00%

EXPORT_SYMBOL(dm_bufio_set_minimum_buffers);
unsigned dm_bufio_get_block_size(struct dm_bufio_client *c) { return c->block_size; }

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Mikulas Patocka15100.00%1100.00%
Total15100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);
sector_t dm_bufio_get_device_size(struct dm_bufio_client *c) { return i_size_read(c->bdev->bd_inode) >> (SECTOR_SHIFT + c->sectors_per_block_bits); }

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Mikulas Patocka28100.00%1100.00%
Total28100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_get_device_size);
sector_t dm_bufio_get_block_number(struct dm_buffer *b) { return b->block; }

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Mikulas Patocka15100.00%1100.00%
Total15100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_get_block_number);
void *dm_bufio_get_block_data(struct dm_buffer *b) { return b->data; }

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Mikulas Patocka16100.00%1100.00%
Total16100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_get_block_data);
void *dm_bufio_get_aux_data(struct dm_buffer *b) { return b + 1; }

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Mikulas Patocka16100.00%1100.00%
Total16100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data);
struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b) { return b->c; }

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Mikulas Patocka17100.00%1100.00%
Total17100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_get_client);
static void drop_buffers(struct dm_bufio_client *c) { struct dm_buffer *b; int i; bool warned = false; BUG_ON(dm_bufio_in_request()); /* * An optimization so that the buffers are not written one-by-one. */ dm_bufio_write_dirty_buffers_async(c); dm_bufio_lock(c); while ((b = __get_unclaimed_buffer(c))) __free_buffer_wake(b); for (i = 0; i < LIST_SIZE; i++) list_for_each_entry(b, &c->lru[i], lru_list) { WARN_ON(!warned); warned = true; DMERR("leaked buffer %llx, hold count %u, list %d", (unsigned long long)b->block, b->hold_count, i); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING print_stack_trace(&b->stack_trace, 1); b->hold_count = 0; /* mark unclaimed to avoid BUG_ON below */ #endif } #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING while ((b = __get_unclaimed_buffer(c))) __free_buffer_wake(b); #endif for (i = 0; i < LIST_SIZE; i++) BUG_ON(!list_empty(&c->lru[i])); dm_bufio_unlock(c); }

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Mikulas Patocka186100.00%2100.00%
Total186100.00%2100.00%

/* * We may not be able to evict this buffer if IO pending or the client * is still using it. Caller is expected to know buffer is too old. * * And if GFP_NOFS is used, we must not do any I/O because we hold * dm_bufio_clients_lock and we would risk deadlock if the I/O gets * rerouted to different bufio client. */
static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp) { if (!(gfp & __GFP_FS)) { if (test_bit(B_READING, &b->state) || test_bit(B_WRITING, &b->state) || test_bit(B_DIRTY, &b->state)) return false; } if (b->hold_count) return false; __make_buffer_clean(b); __unlink_buffer(b); __free_buffer_wake(b); return true; }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka8091.95%266.67%
Joe Thornber78.05%133.33%
Total87100.00%3100.00%


static unsigned long get_retain_buffers(struct dm_bufio_client *c) { unsigned long retain_bytes = ACCESS_ONCE(dm_bufio_retain_bytes); return retain_bytes >> (c->sectors_per_block_bits + SECTOR_SHIFT); }

Contributors

PersonTokensPropCommitsCommitProp
Joe Thornber2268.75%133.33%
Mikulas Patocka1031.25%266.67%
Total32100.00%3100.00%


static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan, gfp_t gfp_mask) { int l; struct dm_buffer *b, *tmp; unsigned long freed = 0; unsigned long count = nr_to_scan; unsigned long retain_target = get_retain_buffers(c); for (l = 0; l < LIST_SIZE; l++) { list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) { if (__try_evict_buffer(b, gfp_mask)) freed++; if (!--nr_to_scan || ((count - freed) <= retain_target)) return freed; cond_resched(); } } return freed; }

Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka6758.26%350.00%
Joe Thornber3227.83%116.67%
Dave Chinner1513.04%116.67%
Peter Zijlstra10.87%116.67%
Total115100.00%6100.00%


static unsigned long dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) { struct dm_bufio_client *c; unsigned long freed; c = container_of(shrink, struct dm_bufio_client, shrinker); if (sc->gfp_mask & __GFP_FS) dm_bufio_lock(c); else if (!dm_bufio_trylock(c)) return SHRINK_STOP; freed = __scan(c, sc->nr_to_scan, sc->gfp_mask); dm_bufio_unlock(c); return freed; }

Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka5766.28%266.67%
Dave Chinner2933.72%133.33%
Total86100.00%3100.00%


static unsigned long dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { struct dm_bufio_client *c = container_of(shrink, struct dm_bufio_client, shrinker); return ACCESS_ONCE(c->n_buffers[LIST_CLEAN]) + ACCESS_ONCE(c->n_buffers[LIST_DIRTY]); }

Contributors

PersonTokensPropCommitsCommitProp
Dave Chinner3056.60%133.33%
Mikulas Patocka2343.40%266.67%
Total53100.00%3100.00%

/* * Create the buffering interface */
struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size, unsigned reserved_buffers, unsigned aux_size, void (*alloc_callback)(struct dm_buffer *), void (*write_callback)(struct dm_buffer *)) { int r; struct dm_bufio_client *c; unsigned i; BUG_ON(block_size < 1 << SECTOR_SHIFT || (block_size & (block_size - 1))); c = kzalloc(sizeof(*c), GFP_KERNEL); if (!c) { r = -ENOMEM; goto bad_client; } c->buffer_tree = RB_ROOT; c->bdev = bdev; c->block_size = block_size; c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT; c->pages_per_block_bits = (__ffs(block_size) >= PAGE_SHIFT) ? __ffs(block_size) - PAGE_SHIFT : 0; c->blocks_per_page_bits = (__ffs(block_size) < PAGE_SHIFT ? PAGE_SHIFT - __ffs(block_size) : 0); c->aux_size = aux_size; c->alloc_callback = alloc_callback; c->write_callback = write_callback; for (i = 0; i < LIST_SIZE; i++) { INIT_LIST_HEAD(&c->lru[i]); c->n_buffers[i] = 0; } mutex_init(&c->lock); INIT_LIST_HEAD(&c->reserved_buffers); c->need_reserved_buffers = reserved_buffers; c->minimum_buffers = DM_BUFIO_MIN_BUFFERS; init_waitqueue_head(&c->free_buffer_wait); c->async_write_error = 0; c->dm_io = dm_io_client_create(); if (IS_ERR(c->dm_io)) { r = PTR_ERR(c->dm_io); goto bad_dm_io; } mutex_lock(&dm_bufio_clients_lock); if (c->blocks_per_page_bits) { if (!DM_BUFIO_CACHE_NAME(c)) { DM_BUFIO_CACHE_NAME(c) = kasprintf(GFP_KERNEL, "dm_bufio_cache-%u", c->block_size); if (!DM_BUFIO_CACHE_NAME(c)) { r = -ENOMEM; mutex_unlock(&dm_bufio_clients_lock); goto bad_cache; } } if (!DM_BUFIO_CACHE(c)) { DM_BUFIO_CACHE(c) = kmem_cache_create(DM_BUFIO_CACHE_NAME(c), c->block_size, c->block_size, 0, NULL); if (!DM_BUFIO_CACHE(c)) { r = -ENOMEM; mutex_unlock(&dm_bufio_clients_lock); goto bad_cache; } } } mutex_unlock(&dm_bufio_clients_lock); while (c->need_reserved_buffers) { struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL); if (!b) { r = -ENOMEM; goto bad_buffer; } __free_buffer_wake(b); } mutex_lock(&dm_bufio_clients_lock); dm_bufio_client_count++; list_add(&c->client_list, &dm_bufio_all_clients); __cache_size_refresh(); mutex_unlock(&dm_bufio_clients_lock); c->shrinker.count_objects = dm_bufio_shrink_count; c->shrinker.scan_objects = dm_bufio_shrink_scan; c->shrinker.seeks = 1; c->shrinker.batch = 0; register_shrinker(&c->shrinker); return c; bad_buffer: bad_cache: while (!list_empty(&c->reserved_buffers)) { struct dm_buffer *b = list_entry(c->reserved_buffers.next, struct dm_buffer, lru_list); list_del(&b->lru_list); free_buffer(b); } dm_io_client_destroy(c->dm_io); bad_dm_io: kfree(c); bad_client: return ERR_PTR(r); }

Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka59897.87%350.00%
Dave Chinner101.64%116.67%
Joe Thornber20.33%116.67%
Greg Thelen10.16%116.67%
Total611100.00%6100.00%

EXPORT_SYMBOL_GPL(dm_bufio_client_create); /* * Free the buffering interface. * It is required that there are no references on any buffers. */
void dm_bufio_client_destroy(struct dm_bufio_client *c) { unsigned i; drop_buffers(c); unregister_shrinker(&c->shrinker); mutex_lock(&dm_bufio_clients_lock); list_del(&c->client_list); dm_bufio_client_count--; __cache_size_refresh(); mutex_unlock(&dm_bufio_clients_lock); BUG_ON(!RB_EMPTY_ROOT(&c->buffer_tree)); BUG_ON(c->need_reserved_buffers); while (!list_empty(&c->reserved_buffers)) { struct dm_buffer *b = list_entry(c->reserved_buffers.next, struct dm_buffer, lru_list); list_del(&b->lru_list); free_buffer(b); } for (i = 0; i < LIST_SIZE; i++) if (c->n_buffers[i]) DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]); for (i = 0; i < LIST_SIZE; i++) BUG_ON(c->n_buffers[i]); dm_io_client_destroy(c->dm_io); kfree(c); }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka18598.93%150.00%
Joe Thornber21.07%150.00%
Total187100.00%2100.00%

EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start) { c->start = start; }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka19100.00%1100.00%
Total19100.00%1100.00%

EXPORT_SYMBOL_GPL(dm_bufio_set_sector_offset);
static unsigned get_max_age_hz(void) { unsigned max_age = ACCESS_ONCE(dm_bufio_max_age); if (max_age > UINT_MAX / HZ) max_age = UINT_MAX / HZ; return max_age * HZ; }

Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka2571.43%266.67%
Joe Thornber1028.57%133.33%
Total35100.00%3100.00%


static bool older_than(struct dm_buffer *b, unsigned long age_hz) { return time_after_eq(jiffies, b->last_accessed + age_hz); }

Contributors

PersonTokensPropCommitsCommitProp
Joe Thornber2074.07%133.33%
Asaf Vertz518.52%133.33%
Mikulas Patocka27.41%133.33%
Total27100.00%3100.00%


static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz) { struct dm_buffer *b, *tmp; unsigned long retain_target = get_retain_buffers(c); unsigned long count; LIST_HEAD(write_list); dm_bufio_lock(c); __check_watermark(c, &write_list); if (unlikely(!list_empty(&write_list))) { dm_bufio_unlock(c); __flush_write_list(&write_list); dm_bufio_lock(c); } count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY]; list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) { if (count <= retain_target) break; if (!older_than(b, age_hz)) break; if (__try_evict_buffer(b, 0)) count--; cond_resched(); } dm_bufio_unlock(c); }

Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka7650.67%350.00%
Joe Thornber7248.00%116.67%
Dave Chinner10.67%116.67%
Peter Zijlstra10.67%116.67%
Total150100.00%6100.00%


static void cleanup_old_buffers(void) { unsigned long max_age_hz = get_max_age_hz(); struct dm_bufio_client *c; mutex_lock(&dm_bufio_clients_lock); __cache_size_refresh(); list_for_each_entry(c, &dm_bufio_all_clients, client_list) __evict_old_buffers(c, max_age_hz); mutex_unlock(&dm_bufio_clients_lock); }

Contributors

PersonTokensPropCommitsCommitProp
Joe Thornber3876.00%133.33%
Mikulas Patocka1224.00%266.67%
Total50100.00%3100.00%

static struct workqueue_struct *dm_bufio_wq; static struct delayed_work dm_bufio_work;
static void work_fn(struct work_struct *w) { cleanup_old_buffers(); queue_delayed_work(dm_bufio_wq, &dm_bufio_work, DM_BUFIO_WORK_TIMER_SECS * HZ); }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka26100.00%1100.00%
Total26100.00%1100.00%

/*---------------------------------------------------------------- * Module setup *--------------------------------------------------------------*/ /* * This is called only once for the whole dm_bufio module. * It initializes memory limit. */
static int __init dm_bufio_init(void) { __u64 mem; dm_bufio_allocated_kmem_cache = 0; dm_bufio_allocated_get_free_pages = 0; dm_bufio_allocated_vmalloc = 0; dm_bufio_current_allocated = 0; memset(&dm_bufio_caches, 0, sizeof dm_bufio_caches); memset(&dm_bufio_cache_names, 0, sizeof dm_bufio_cache_names); mem = (__u64)((totalram_pages - totalhigh_pages) * DM_BUFIO_MEMORY_PERCENT / 100) << PAGE_SHIFT; if (mem > ULONG_MAX) mem = ULONG_MAX; #ifdef CONFIG_MMU /* * Get the size of vmalloc space the same way as VMALLOC_TOTAL * in fs/proc/internal.h */ if (mem > (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100) mem = (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100; #endif dm_bufio_default_cache_size = mem; mutex_lock(&dm_bufio_clients_lock); __cache_size_refresh(); mutex_unlock(&dm_bufio_clients_lock); dm_bufio_wq = alloc_workqueue("dm_bufio_cache", WQ_MEM_RECLAIM, 0); if (!dm_bufio_wq) return -ENOMEM; INIT_DELAYED_WORK(&dm_bufio_work, work_fn); queue_delayed_work(dm_bufio_wq, &dm_bufio_work, DM_BUFIO_WORK_TIMER_SECS * HZ); return 0; }

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PersonTokensPropCommitsCommitProp
Mikulas Patocka16897.11%266.67%
Bhaktipriya Shridhar52.89%133.33%
Total173100.00%3100.00%

/* * This is called once when unloading the dm_bufio module. */
static void __exit dm_bufio_exit(void) { int bug = 0; int i; cancel_delayed_work_sync(&dm_bufio_work); destroy_workqueue(dm_bufio_wq); for (i = 0; i < ARRAY_SIZE(dm_bufio_caches); i++) kmem_cache_destroy(dm_bufio_caches[i]); for (i = 0; i < ARRAY_SIZE(dm_bufio_cache_names); i++) kfree(dm_bufio_cache_names[i]); if (dm_bufio_client_count) { DMCRIT("%s: dm_bufio_client_count leaked: %d", __func__, dm_bufio_client_count); bug = 1; } if (dm_bufio_current_allocated) { DMCRIT("%s: dm_bufio_current_allocated leaked: %lu", __func__, dm_bufio_current_allocated); bug = 1; } if (dm_bufio_allocated_get_free_pages) { DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu", __func__, dm_bufio_allocated_get_free_pages); bug = 1; } if (dm_bufio_allocated_vmalloc) { DMCRIT("%s: dm_bufio_vmalloc leaked: %lu", __func__, dm_bufio_allocated_vmalloc); bug = 1; } BUG_ON(bug); }

Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka15296.82%133.33%
Anup Limbu31.91%133.33%
Julia Lawall21.27%133.33%
Total157100.00%3100.00%

module_init(dm_bufio_init) module_exit(dm_bufio_exit) module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache"); module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds"); module_param_named(retain_bytes, dm_bufio_retain_bytes, ulong, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory"); module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory"); module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO); MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc"); module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO); MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages"); module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO); MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc"); module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO); MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache"); MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>"); MODULE_DESCRIPTION(DM_NAME " buffered I/O library"); MODULE_LICENSE("GPL");

Overall Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka693989.84%2142.00%
Joe Thornber5096.59%36.00%
Dave Chinner851.10%12.00%
Christoph Hellwig670.87%48.00%
Darrick J. Wong390.50%12.00%
Michael Christie240.31%24.00%
Peter Zijlstra130.17%24.00%
Neil Brown90.12%12.00%
Asaf Vertz80.10%12.00%
Bhaktipriya Shridhar50.06%12.00%
Stephen Rothwell30.04%12.00%
Lei Ming30.04%12.00%
Anup Limbu30.04%12.00%
Ingo Molnar30.04%12.00%
Dan Carpenter20.03%12.00%
Kent Overstreet20.03%12.00%
Jan Kara20.03%12.00%
Douglas Anderson20.03%12.00%
Julia Lawall20.03%12.00%
Al Viro10.01%12.00%
Wei Yongjun10.01%12.00%
Greg Thelen10.01%12.00%
Davidlohr Bueso A10.01%12.00%
Total7724100.00%50100.00%
Directory: drivers/md
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