diff options
| -rw-r--r-- | Documentation/filesystems/caching/backend-api.txt | 26 | ||||
| -rw-r--r-- | Documentation/filesystems/caching/operations.txt | 2 | ||||
| -rw-r--r-- | fs/cachefiles/rdwr.c | 31 | ||||
| -rw-r--r-- | fs/fscache/object.c | 2 | ||||
| -rw-r--r-- | fs/fscache/operation.c | 91 | ||||
| -rw-r--r-- | fs/fscache/page.c | 25 | ||||
| -rw-r--r-- | include/linux/fscache-cache.h | 37 |
7 files changed, 164 insertions, 50 deletions
diff --git a/Documentation/filesystems/caching/backend-api.txt b/Documentation/filesystems/caching/backend-api.txt index 382d52c..f4769b9 100644 --- a/Documentation/filesystems/caching/backend-api.txt +++ b/Documentation/filesystems/caching/backend-api.txt @@ -419,7 +419,10 @@ performed on the denizens of the cache. These are held in a structure of type: If an I/O error occurs, fscache_io_error() should be called and -ENOBUFS returned if possible or fscache_end_io() called with a suitable error - code.. + code. + + fscache_put_retrieval() should be called after a page or pages are dealt + with. This will complete the operation when all pages are dealt with. (*) Request pages be read from cache [mandatory]: @@ -526,6 +529,27 @@ FS-Cache provides some utilities that a cache backend may make use of: error value should be 0 if successful and an error otherwise. + (*) Record that one or more pages being retrieved or allocated have been dealt + with: + + void fscache_retrieval_complete(struct fscache_retrieval *op, + int n_pages); + + This is called to record the fact that one or more pages have been dealt + with and are no longer the concern of this operation. When the number of + pages remaining in the operation reaches 0, the operation will be + completed. + + + (*) Record operation completion: + + void fscache_op_complete(struct fscache_operation *op); + + This is called to record the completion of an operation. This deducts + this operation from the parent object's run state, potentially permitting + one or more pending operations to start running. + + (*) Set highest store limit: void fscache_set_store_limit(struct fscache_object *object, diff --git a/Documentation/filesystems/caching/operations.txt b/Documentation/filesystems/caching/operations.txt index b6b070c..bee2a5f 100644 --- a/Documentation/filesystems/caching/operations.txt +++ b/Documentation/filesystems/caching/operations.txt @@ -174,7 +174,7 @@ Operations are used through the following procedure: necessary (the object might have died whilst the thread was waiting). When it has finished doing its processing, it should call - fscache_put_operation() on it. + fscache_op_complete() and fscache_put_operation() on it. (4) The operation holds an effective lock upon the object, preventing other exclusive ops conflicting until it is released. The operation can be diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c index bf123d9..93a0815 100644 --- a/fs/cachefiles/rdwr.c +++ b/fs/cachefiles/rdwr.c @@ -197,6 +197,7 @@ static void cachefiles_read_copier(struct fscache_operation *_op) fscache_end_io(op, monitor->netfs_page, error); page_cache_release(monitor->netfs_page); + fscache_retrieval_complete(op, 1); fscache_put_retrieval(op); kfree(monitor); @@ -339,6 +340,7 @@ backing_page_already_uptodate: copy_highpage(netpage, backpage); fscache_end_io(op, netpage, 0); + fscache_retrieval_complete(op, 1); success: _debug("success"); @@ -360,6 +362,7 @@ read_error: goto out; io_error: cachefiles_io_error_obj(object, "Page read error on backing file"); + fscache_retrieval_complete(op, 1); ret = -ENOBUFS; goto out; @@ -369,6 +372,7 @@ nomem_monitor: fscache_put_retrieval(monitor->op); kfree(monitor); nomem: + fscache_retrieval_complete(op, 1); _leave(" = -ENOMEM"); return -ENOMEM; } @@ -407,7 +411,7 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op, _enter("{%p},{%lx},,,", object, page->index); if (!object->backer) - return -ENOBUFS; + goto enobufs; inode = object->backer->d_inode; ASSERT(S_ISREG(inode->i_mode)); @@ -416,7 +420,7 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op, /* calculate the shift required to use bmap */ if (inode->i_sb->s_blocksize > PAGE_SIZE) - return -ENOBUFS; + goto enobufs; shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits; @@ -448,13 +452,19 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op, } else if (cachefiles_has_space(cache, 0, 1) == 0) { /* there's space in the cache we can use */ fscache_mark_page_cached(op, page); + fscache_retrieval_complete(op, 1); ret = -ENODATA; } else { - ret = -ENOBUFS; + goto enobufs; } _leave(" = %d", ret); return ret; + +enobufs: + fscache_retrieval_complete(op, 1); + _leave(" = -ENOBUFS"); + return -ENOBUFS; } /* @@ -632,6 +642,7 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object, /* the netpage is unlocked and marked up to date here */ fscache_end_io(op, netpage, 0); + fscache_retrieval_complete(op, 1); page_cache_release(netpage); netpage = NULL; continue; @@ -659,6 +670,7 @@ out: list_for_each_entry_safe(netpage, _n, list, lru) { list_del(&netpage->lru); page_cache_release(netpage); + fscache_retrieval_complete(op, 1); } _leave(" = %d", ret); @@ -707,7 +719,7 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op, *nr_pages); if (!object->backer) - return -ENOBUFS; + goto all_enobufs; space = 1; if (cachefiles_has_space(cache, 0, *nr_pages) < 0) @@ -720,7 +732,7 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op, /* calculate the shift required to use bmap */ if (inode->i_sb->s_blocksize > PAGE_SIZE) - return -ENOBUFS; + goto all_enobufs; shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits; @@ -760,7 +772,10 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op, nrbackpages++; } else if (space && pagevec_add(&pagevec, page) == 0) { fscache_mark_pages_cached(op, &pagevec); + fscache_retrieval_complete(op, 1); ret = -ENODATA; + } else { + fscache_retrieval_complete(op, 1); } } @@ -781,6 +796,10 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op, _leave(" = %d [nr=%u%s]", ret, *nr_pages, list_empty(pages) ? " empty" : ""); return ret; + +all_enobufs: + fscache_retrieval_complete(op, *nr_pages); + return -ENOBUFS; } /* @@ -815,6 +834,7 @@ int cachefiles_allocate_page(struct fscache_retrieval *op, else ret = -ENOBUFS; + fscache_retrieval_complete(op, 1); _leave(" = %d", ret); return ret; } @@ -864,6 +884,7 @@ int cachefiles_allocate_pages(struct fscache_retrieval *op, ret = -ENOBUFS; } + fscache_retrieval_complete(op, *nr_pages); _leave(" = %d", ret); return ret; } diff --git a/fs/fscache/object.c b/fs/fscache/object.c index b6b897c..773bc79 100644 --- a/fs/fscache/object.c +++ b/fs/fscache/object.c @@ -587,8 +587,6 @@ static void fscache_object_available(struct fscache_object *object) if (object->n_in_progress == 0) { if (object->n_ops > 0) { ASSERTCMP(object->n_ops, >=, object->n_obj_ops); - ASSERTIF(object->n_ops > object->n_obj_ops, - !list_empty(&object->pending_ops)); fscache_start_operations(object); } else { ASSERT(list_empty(&object->pending_ops)); diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c index c857ab8..748f955 100644 --- a/fs/fscache/operation.c +++ b/fs/fscache/operation.c @@ -37,6 +37,7 @@ void fscache_enqueue_operation(struct fscache_operation *op) ASSERT(op->processor != NULL); ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE); ASSERTCMP(atomic_read(&op->usage), >, 0); + ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS); fscache_stat(&fscache_n_op_enqueue); switch (op->flags & FSCACHE_OP_TYPE) { @@ -64,6 +65,9 @@ EXPORT_SYMBOL(fscache_enqueue_operation); static void fscache_run_op(struct fscache_object *object, struct fscache_operation *op) { + ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING); + + op->state = FSCACHE_OP_ST_IN_PROGRESS; object->n_in_progress++; if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) wake_up_bit(&op->flags, FSCACHE_OP_WAITING); @@ -80,22 +84,23 @@ static void fscache_run_op(struct fscache_object *object, int fscache_submit_exclusive_op(struct fscache_object *object, struct fscache_operation *op) { - int ret; - _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id); + ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED); + ASSERTCMP(atomic_read(&op->usage), >, 0); + spin_lock(&object->lock); ASSERTCMP(object->n_ops, >=, object->n_in_progress); ASSERTCMP(object->n_ops, >=, object->n_exclusive); ASSERT(list_empty(&op->pend_link)); - ret = -ENOBUFS; + op->state = FSCACHE_OP_ST_PENDING; if (fscache_object_is_active(object)) { op->object = object; object->n_ops++; object->n_exclusive++; /* reads and writes must wait */ - if (object->n_ops > 1) { + if (object->n_in_progress > 0) { atomic_inc(&op->usage); list_add_tail(&op->pend_link, &object->pending_ops); fscache_stat(&fscache_n_op_pend); @@ -111,7 +116,6 @@ int fscache_submit_exclusive_op(struct fscache_object *object, /* need to issue a new write op after this */ clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); - ret = 0; } else if (object->state == FSCACHE_OBJECT_CREATING) { op->object = object; object->n_ops++; @@ -119,14 +123,13 @@ int fscache_submit_exclusive_op(struct fscache_object *object, atomic_inc(&op->usage); list_add_tail(&op->pend_link, &object->pending_ops); fscache_stat(&fscache_n_op_pend); - ret = 0; } else { /* not allowed to submit ops in any other state */ BUG(); } spin_unlock(&object->lock); - return ret; + return 0; } /* @@ -186,6 +189,7 @@ int fscache_submit_op(struct fscache_object *object, _enter("{OBJ%x OP%x},{%u}", object->debug_id, op->debug_id, atomic_read(&op->usage)); + ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED); ASSERTCMP(atomic_read(&op->usage), >, 0); spin_lock(&object->lock); @@ -196,6 +200,7 @@ int fscache_submit_op(struct fscache_object *object, ostate = object->state; smp_rmb(); + op->state = FSCACHE_OP_ST_PENDING; if (fscache_object_is_active(object)) { op->object = object; object->n_ops++; @@ -225,12 +230,15 @@ int fscache_submit_op(struct fscache_object *object, object->state == FSCACHE_OBJECT_LC_DYING || object->state == FSCACHE_OBJECT_WITHDRAWING) { fscache_stat(&fscache_n_op_rejected); + op->state = FSCACHE_OP_ST_CANCELLED; ret = -ENOBUFS; } else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) { fscache_report_unexpected_submission(object, op, ostate); ASSERT(!fscache_object_is_active(object)); + op->state = FSCACHE_OP_ST_CANCELLED; ret = -ENOBUFS; } else { + op->state = FSCACHE_OP_ST_CANCELLED; ret = -ENOBUFS; } @@ -290,13 +298,18 @@ int fscache_cancel_op(struct fscache_operation *op) _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id); + ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING); + ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED); + ASSERTCMP(atomic_read(&op->usage), >, 0); + spin_lock(&object->lock); ret = -EBUSY; - if (!list_empty(&op->pend_link)) { + if (op->state == FSCACHE_OP_ST_PENDING) { + ASSERT(!list_empty(&op->pend_link)); fscache_stat(&fscache_n_op_cancelled); list_del_init(&op->pend_link); - object->n_ops--; + op->state = FSCACHE_OP_ST_CANCELLED; if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) object->n_exclusive--; if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags)) @@ -311,6 +324,37 @@ int fscache_cancel_op(struct fscache_operation *op) } /* + * Record the completion of an in-progress operation. + */ +void fscache_op_complete(struct fscache_operation *op) +{ + struct fscache_object *object = op->object; + + _enter("OBJ%x", object->debug_id); + + ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS); + ASSERTCMP(object->n_in_progress, >, 0); + ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags), + object->n_exclusive, >, 0); + ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags), + object->n_in_progress, ==, 1); + + spin_lock(&object->lock); + + op->state = FSCACHE_OP_ST_COMPLETE; + + if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) + object->n_exclusive--; + object->n_in_progress--; + if (object->n_in_progress == 0) + fscache_start_operations(object); + + spin_unlock(&object->lock); + _leave(""); +} +EXPORT_SYMBOL(fscache_op_complete); + +/* * release an operation * - queues pending ops if this is the last in-progress op */ @@ -328,8 +372,9 @@ void fscache_put_operation(struct fscache_operation *op) return; _debug("PUT OP"); - if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags)) - BUG(); + ASSERTIFCMP(op->state != FSCACHE_OP_ST_COMPLETE, + op->state, ==, FSCACHE_OP_ST_CANCELLED); + op->state = FSCACHE_OP_ST_DEAD; fscache_stat(&fscache_n_op_release); @@ -365,16 +410,6 @@ void fscache_put_operation(struct fscache_operation *op) return; } - if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { - ASSERTCMP(object->n_exclusive, >, 0); - object->n_exclusive--; - } - - ASSERTCMP(object->n_in_progress, >, 0); - object->n_in_progress--; - if (object->n_in_progress == 0) - fscache_start_operations(object); - ASSERTCMP(object->n_ops, >, 0); object->n_ops--; if (object->n_ops == 0) @@ -413,23 +448,14 @@ void fscache_operation_gc(struct work_struct *work) spin_unlock(&cache->op_gc_list_lock); object = op->object; + spin_lock(&object->lock); _debug("GC DEFERRED REL OBJ%x OP%x", object->debug_id, op->debug_id); fscache_stat(&fscache_n_op_gc); ASSERTCMP(atomic_read(&op->usage), ==, 0); - - spin_lock(&object->lock); - if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) { - ASSERTCMP(object->n_exclusive, >, 0); - object->n_exclusive--; - } - - ASSERTCMP(object->n_in_progress, >, 0); - object->n_in_progress--; - if (object->n_in_progress == 0) - fscache_start_operations(object); + ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD); ASSERTCMP(object->n_ops, >, 0); object->n_ops--; @@ -437,6 +463,7 @@ void fscache_operation_gc(struct work_struct *work) fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED); spin_unlock(&object->lock); + kfree(op); } while (count++ < 20); diff --git a/fs/fscache/page.c b/fs/fscache/page.c index 248a12e..b38b13d 100644 --- a/fs/fscache/page.c +++ b/fs/fscache/page.c @@ -162,6 +162,7 @@ static void fscache_attr_changed_op(struct fscache_operation *op) fscache_abort_object(object); } + fscache_op_complete(op); _leave(""); } @@ -223,6 +224,8 @@ static void fscache_release_retrieval_op(struct fscache_operation *_op) _enter("{OP%x}", op->op.debug_id); + ASSERTCMP(op->n_pages, ==, 0); + fscache_hist(fscache_retrieval_histogram, op->start_time); if (op->context) fscache_put_context(op->op.object->cookie, op->context); @@ -320,6 +323,11 @@ static int fscache_wait_for_retrieval_activation(struct fscache_object *object, _debug("<<< GO"); check_if_dead: + if (op->op.state == FSCACHE_OP_ST_CANCELLED) { + fscache_stat(stat_object_dead); + _leave(" = -ENOBUFS [cancelled]"); + return -ENOBUFS; + } if (unlikely(fscache_object_is_dead(object))) { fscache_stat(stat_object_dead); return -ENOBUFS; @@ -364,6 +372,7 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, _leave(" = -ENOMEM"); return -ENOMEM; } + op->n_pages = 1; spin_lock(&cookie->lock); @@ -375,10 +384,10 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, ASSERTCMP(object->state, >, FSCACHE_OBJECT_LOOKING_UP); atomic_inc(&object->n_reads); - set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); + __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); if (fscache_submit_op(object, &op->op) < 0) - goto nobufs_unlock; + goto nobufs_unlock_dec; spin_unlock(&cookie->lock); fscache_stat(&fscache_n_retrieval_ops); @@ -425,6 +434,8 @@ error: _leave(" = %d", ret); return ret; +nobufs_unlock_dec: + atomic_dec(&object->n_reads); nobufs_unlock: spin_unlock(&cookie->lock); kfree(op); @@ -482,6 +493,7 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, op = fscache_alloc_retrieval(mapping, end_io_func, context); if (!op) return -ENOMEM; + op->n_pages = *nr_pages; spin_lock(&cookie->lock); @@ -491,10 +503,10 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, struct fscache_object, cookie_link); atomic_inc(&object->n_reads); - set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); + __set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags); if (fscache_submit_op(object, &op->op) < 0) - goto nobufs_unlock; + goto nobufs_unlock_dec; spin_unlock(&cookie->lock); fscache_stat(&fscache_n_retrieval_ops); @@ -541,6 +553,8 @@ error: _leave(" = %d", ret); return ret; +nobufs_unlock_dec: + atomic_dec(&object->n_reads); nobufs_unlock: spin_unlock(&cookie->lock); kfree(op); @@ -583,6 +597,7 @@ int __fscache_alloc_page(struct fscache_cookie *cookie, op = fscache_alloc_retrieval(page->mapping, NULL, NULL); if (!op) return -ENOMEM; + op->n_pages = 1; spin_lock(&cookie->lock); @@ -696,6 +711,7 @@ static void fscache_write_op(struct fscache_operation *_op) fscache_end_page_write(object, page); if (ret < 0) { fscache_abort_object(object); + fscache_op_complete(&op->op); } else { fscache_enqueue_operation(&op->op); } @@ -710,6 +726,7 @@ superseded: spin_unlock(&cookie->stores_lock); clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); spin_unlock(&object->lock); + fscache_op_complete(&op->op); _leave(""); } diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h index e3d6d93..f5facd1 100644 --- a/include/linux/fscache-cache.h +++ b/include/linux/fscache-cache.h @@ -75,6 +75,16 @@ extern wait_queue_head_t fscache_cache_cleared_wq; typedef void (*fscache_operation_release_t)(struct fscache_operation *op); typedef void (*fscache_operation_processor_t)(struct fscache_operation *op); +enum fscache_operation_state { + FSCACHE_OP_ST_BLANK, /* Op is not yet submitted */ + FSCACHE_OP_ST_INITIALISED, /* Op is initialised */ + FSCACHE_OP_ST_PENDING, /* Op is blocked from running */ + FSCACHE_OP_ST_IN_PROGRESS, /* Op is in progress */ + FSCACHE_OP_ST_COMPLETE, /* Op is complete */ + FSCACHE_OP_ST_CANCELLED, /* Op has been cancelled */ + FSCACHE_OP_ST_DEAD /* Op is now dead */ +}; + struct fscache_operation { struct work_struct work; /* record for async ops */ struct list_head pend_link; /* link in object->pending_ops */ @@ -86,10 +96,10 @@ struct fscache_operation { #define FSCACHE_OP_MYTHREAD 0x0002 /* - processing is done be issuing thread, not pool */ #define FSCACHE_OP_WAITING 4 /* cleared when op is woken */ #define FSCACHE_OP_EXCLUSIVE 5 /* exclusive op, other ops must wait */ -#define FSCACHE_OP_DEAD 6 /* op is now dead */ -#define FSCACHE_OP_DEC_READ_CNT 7 /* decrement object->n_reads on destruction */ -#define FSCACHE_OP_KEEP_FLAGS 0xc0 /* flags to keep when repurposing an op */ +#define FSCACHE_OP_DEC_READ_CNT 6 /* decrement object->n_reads on destruction */ +#define FSCACHE_OP_KEEP_FLAGS 0x0070 /* flags to keep when repurposing an op */ + enum fscache_operation_state state; atomic_t usage; unsigned debug_id; /* debugging ID */ @@ -106,6 +116,7 @@ extern atomic_t fscache_op_debug_id; extern void fscache_op_work_func(struct work_struct *work); extern void fscache_enqueue_operation(struct fscache_operation *); +extern void fscache_op_complete(struct fscache_operation *); extern void fscache_put_operation(struct fscache_operation *); /** @@ -122,6 +133,7 @@ static inline void fscache_operation_init(struct fscache_operation *op, { INIT_WORK(&op->work, fscache_op_work_func); atomic_set(&op->usage, 1); + op->state = FSCACHE_OP_ST_INITIALISED; op->debug_id = atomic_inc_return(&fscache_op_debug_id); op->processor = processor; op->release = release; @@ -138,6 +150,7 @@ struct fscache_retrieval { void *context; /* netfs read context (pinned) */ struct list_head to_do; /* list of things to be done by the backend */ unsigned long start_time; /* time at which retrieval started */ + unsigned n_pages; /* number of pages to be retrieved */ }; typedef int (*fscache_page_retrieval_func_t)(struct fscache_retrieval *op, @@ -174,8 +187,22 @@ static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op) } /** + * fscache_retrieval_complete - Record (partial) completion of a retrieval + * @op: The retrieval operation affected + * @n_pages: The number of pages to account for + */ +static inline void fscache_retrieval_complete(struct fscache_retrieval *op, + int n_pages) +{ + op->n_pages -= n_pages; + if (op->n_pages <= 0) + fscache_op_complete(&op->op); +} + +/** * fscache_put_retrieval - Drop a reference to a retrieval operation * @op: The retrieval operation affected + * @n_pages: The number of pages to account for * * Drop a reference to a retrieval operation. */ @@ -333,10 +360,10 @@ struct fscache_object { int debug_id; /* debugging ID */ int n_children; /* number of child objects */ - int n_ops; /* number of ops outstanding on object */ + int n_ops; /* number of extant ops on object */ int n_obj_ops; /* number of object ops outstanding on object */ int n_in_progress; /* number of ops in progress */ - int n_exclusive; /* number of exclusive ops queued */ + int n_exclusive; /* number of exclusive ops queued or in progress */ atomic_t n_reads; /* number of read ops in progress */ spinlock_t lock; /* state and operations lock */ |
