diff options
Diffstat (limited to 'include/sys/dmu.h')
| -rw-r--r-- | include/sys/dmu.h | 133 |
1 files changed, 110 insertions, 23 deletions
diff --git a/include/sys/dmu.h b/include/sys/dmu.h index 127cdcdb7..b2f1efae0 100644 --- a/include/sys/dmu.h +++ b/include/sys/dmu.h @@ -24,6 +24,7 @@ * Copyright 2011 Nexenta Systems, Inc. All rights reserved. * Copyright (c) 2012, Joyent, Inc. All rights reserved. * Copyright 2014 HybridCluster. All rights reserved. + * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved. */ /* Portions Copyright 2010 Robert Milkowski */ @@ -39,11 +40,9 @@ * dmu_spa.h. */ +#include <sys/zfs_context.h> #include <sys/inttypes.h> -#include <sys/types.h> -#include <sys/param.h> #include <sys/cred.h> -#include <sys/time.h> #include <sys/fs/zfs.h> #include <sys/uio.h> @@ -288,8 +287,6 @@ typedef struct dmu_buf { void *db_data; /* data in buffer */ } dmu_buf_t; -typedef void dmu_buf_evict_func_t(struct dmu_buf *db, void *user_ptr); - /* * The names of zap entries in the DIRECTORY_OBJECT of the MOS. */ @@ -475,36 +472,126 @@ int dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset, uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp); void dmu_buf_rele_array(dmu_buf_t **, int numbufs, void *tag); +typedef void dmu_buf_evict_func_t(void *user_ptr); + +/* + * A DMU buffer user object may be associated with a dbuf for the + * duration of its lifetime. This allows the user of a dbuf (client) + * to attach private data to a dbuf (e.g. in-core only data such as a + * dnode_children_t, zap_t, or zap_leaf_t) and be optionally notified + * when that dbuf has been evicted. Clients typically respond to the + * eviction notification by freeing their private data, thus ensuring + * the same lifetime for both dbuf and private data. + * + * The mapping from a dmu_buf_user_t to any client private data is the + * client's responsibility. All current consumers of the API with private + * data embed a dmu_buf_user_t as the first member of the structure for + * their private data. This allows conversions between the two types + * with a simple cast. Since the DMU buf user API never needs access + * to the private data, other strategies can be employed if necessary + * or convenient for the client (e.g. using container_of() to do the + * conversion for private data that cannot have the dmu_buf_user_t as + * its first member). + * + * Eviction callbacks are executed without the dbuf mutex held or any + * other type of mechanism to guarantee that the dbuf is still available. + * For this reason, users must assume the dbuf has already been freed + * and not reference the dbuf from the callback context. + * + * Users requesting "immediate eviction" are notified as soon as the dbuf + * is only referenced by dirty records (dirties == holds). Otherwise the + * notification occurs after eviction processing for the dbuf begins. + */ +typedef struct dmu_buf_user { + /* + * Asynchronous user eviction callback state. + */ + taskq_ent_t dbu_tqent; + + /* This instance's eviction function pointer. */ + dmu_buf_evict_func_t *dbu_evict_func; +#ifdef ZFS_DEBUG + /* + * Pointer to user's dbuf pointer. NULL for clients that do + * not associate a dbuf with their user data. + * + * The dbuf pointer is cleared upon eviction so as to catch + * use-after-evict bugs in clients. + */ + dmu_buf_t **dbu_clear_on_evict_dbufp; +#endif +} dmu_buf_user_t; + +/* + * Initialize the given dmu_buf_user_t instance with the eviction function + * evict_func, to be called when the user is evicted. + * + * NOTE: This function should only be called once on a given dmu_buf_user_t. + * To allow enforcement of this, dbu must already be zeroed on entry. + */ +#ifdef __lint +/* Very ugly, but it beats issuing suppression directives in many Makefiles. */ +extern void +dmu_buf_init_user(dmu_buf_user_t *dbu, dmu_buf_evict_func_t *evict_func, + dmu_buf_t **clear_on_evict_dbufp); +#else /* __lint */ +static inline void +dmu_buf_init_user(dmu_buf_user_t *dbu, dmu_buf_evict_func_t *evict_func, + dmu_buf_t **clear_on_evict_dbufp) +{ + ASSERT(dbu->dbu_evict_func == NULL); + ASSERT(evict_func != NULL); + dbu->dbu_evict_func = evict_func; +#ifdef ZFS_DEBUG + dbu->dbu_clear_on_evict_dbufp = clear_on_evict_dbufp; +#endif +} +#endif /* __lint */ + /* - * Returns NULL on success, or the existing user ptr if it's already - * been set. + * Attach user data to a dbuf and mark it for normal (when the dbuf's + * data is cleared or its reference count goes to zero) eviction processing. * - * user_ptr is for use by the user and can be obtained via dmu_buf_get_user(). + * Returns NULL on success, or the existing user if another user currently + * owns the buffer. + */ +void *dmu_buf_set_user(dmu_buf_t *db, dmu_buf_user_t *user); + +/* + * Attach user data to a dbuf and mark it for immediate (its dirty and + * reference counts are equal) eviction processing. * - * If non-NULL, pageout func will be called when this buffer is being - * excised from the cache, so that you can clean up the data structure - * pointed to by user_ptr. + * Returns NULL on success, or the existing user if another user currently + * owns the buffer. + */ +void *dmu_buf_set_user_ie(dmu_buf_t *db, dmu_buf_user_t *user); + +/* + * Replace the current user of a dbuf. * - * dmu_evict_user() will call the pageout func for all buffers in a - * objset with a given pageout func. + * If given the current user of a dbuf, replaces the dbuf's user with + * "new_user" and returns the user data pointer that was replaced. + * Otherwise returns the current, and unmodified, dbuf user pointer. */ -void *dmu_buf_set_user(dmu_buf_t *db, void *user_ptr, - dmu_buf_evict_func_t *pageout_func); +void *dmu_buf_replace_user(dmu_buf_t *db, + dmu_buf_user_t *old_user, dmu_buf_user_t *new_user); + /* - * set_user_ie is the same as set_user, but request immediate eviction - * when hold count goes to zero. + * Remove the specified user data for a DMU buffer. + * + * Returns the user that was removed on success, or the current user if + * another user currently owns the buffer. */ -void *dmu_buf_set_user_ie(dmu_buf_t *db, void *user_ptr, - dmu_buf_evict_func_t *pageout_func); -void *dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, - void *user_ptr, dmu_buf_evict_func_t *pageout_func); -void dmu_evict_user(objset_t *os, dmu_buf_evict_func_t *func); +void *dmu_buf_remove_user(dmu_buf_t *db, dmu_buf_user_t *user); /* - * Returns the user_ptr set with dmu_buf_set_user(), or NULL if not set. + * Returns the user data (dmu_buf_user_t *) associated with this dbuf. */ void *dmu_buf_get_user(dmu_buf_t *db); +/* Block until any in-progress dmu buf user evictions complete. */ +void dmu_buf_user_evict_wait(void); + /* * Returns the blkptr associated with this dbuf, or NULL if not set. */ |