*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; If not, see
- * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
+ * http://www.gnu.org/licenses/gpl-2.0.html
*
* GPL HEADER END
*/
* Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
* Use is subject to license terms.
*
- * Copyright (c) 2012, 2013, Intel Corporation.
+ * Copyright (c) 2012, 2014, Intel Corporation.
*/
/*
* This file is part of Lustre, http://www.lustre.org/
* Lustre is a trademark of Sun Microsystems, Inc.
- *
+ */
+/*
* lustre/ofd/ofd_grant.c
*
- * Author: Johann Lombardi <johann@whamcloud..com>
+ * This file provides code related to grant space management on Object Storage
+ * Targets (OSTs). Grant is a mechanism used by client nodes to reserve disk
+ * space on OSTs for the data writeback cache. The Lustre client is thus assured
+ * that enough space will be available when flushing dirty pages asynchronously.
+ * Each client node is granted an initial amount of reserved space at connect
+ * time and gets additional space back from OST in bulk write reply.
+ *
+ * This file handles the core logic for:
+ * - grant allocation strategy
+ * - maintaining per-client as well as global grant space accounting
+ * - processing grant information packed in incoming requests
+ * - allocating server-side grant space for synchronous write RPCs which did not
+ * consume grant on the client side (OBD_BRW_FROM_GRANT flag not set). If not
+ * enough space is available, such RPCs fail with ENOSPC
+ *
+ * Author: Johann Lombardi <johann.lombardi@intel.com>
*/
#define DEBUG_SUBSYSTEM S_FILTER
}
/**
- * Perform extra sanity checks for grant accounting. This is done at connect,
- * disconnect, and statfs RPC time, so it shouldn't be too bad. We can
- * always get rid of it or turn it off when we know accounting is good.
+ * Perform extra sanity checks for grant accounting.
*
- * \param obd - is the device to check
- * \param func - is the function to call if an inconsistency is found
+ * This function scans the export list, sanity checks per-export grant counters
+ * and verifies accuracy of global grant accounting. If an inconsistency is
+ * found, a CERROR is printed with the function name \func that was passed as
+ * argument. LBUG is only called in case of serious counter corruption (i.e.
+ * value larger than the device size).
+ * Those sanity checks can be pretty expensive and are disabled if the OBD
+ * device has more than 100 connected exports.
+ *
+ * \param[in] obd OBD device for which grant accounting should be
+ * verified
+ * \param[in] func caller's function name
*/
void ofd_grant_sanity_check(struct obd_device *obd, const char *func)
{
- struct filter_export_data *fed;
- struct ofd_device *ofd = ofd_dev(obd->obd_lu_dev);
- struct obd_export *exp;
- obd_size maxsize;
- obd_size tot_dirty = 0;
- obd_size tot_pending = 0;
- obd_size tot_granted = 0;
- obd_size fo_tot_dirty, fo_tot_pending;
- obd_size fo_tot_granted;
+ struct ofd_device *ofd = ofd_dev(obd->obd_lu_dev);
+ struct obd_export *exp;
+ obd_size maxsize;
+ obd_size tot_dirty = 0;
+ obd_size tot_pending = 0;
+ obd_size tot_granted = 0;
+ obd_size fo_tot_granted;
+ obd_size fo_tot_pending;
+ obd_size fo_tot_dirty;
if (cfs_list_empty(&obd->obd_exports))
return;
spin_lock(&obd->obd_dev_lock);
spin_lock(&ofd->ofd_grant_lock);
cfs_list_for_each_entry(exp, &obd->obd_exports, exp_obd_chain) {
- int error = 0;
+ struct filter_export_data *fed;
+ int error = 0;
fed = &exp->exp_filter_data;
}
/**
- * Get fresh statfs information from the OSD layer if the cache is older than 1s
- * or if force is set. The OSD layer is in charge of estimating data & metadata
- * overhead.
+ * Update cached statfs information from the OSD layer
*
- * \param env - is the lu environment passed by the caller
- * \param exp - export used to print client info in debug messages
- * \param force - is used to force a refresh of statfs information
- * \param from_cache - returns whether the statfs information are
- * taken from cache
+ * Refresh statfs information cached in ofd::ofd_osfs if the cache is older
+ * than 1s or if force is set. The OSD layer is in charge of estimating data &
+ * metadata overhead.
+ * This function can sleep so it should not be called with any spinlock held.
+ *
+ * \param[in] env LU environment passed by the caller
+ * \param[in] exp export used to print client info in debug
+ * messages
+ * \param[in] force force a refresh of statfs information
+ * \param[out] from_cache returns whether the statfs information are
+ * taken from cache
*/
static void ofd_grant_statfs(const struct lu_env *env, struct obd_export *exp,
int force, int *from_cache)
}
/**
- * Figure out how much space is available on the backend filesystem.
+ * Figure out how much space is available on the backend filesystem after
+ * removing grant space already booked by clients.
+ *
* This is done by accessing cached statfs data previously populated by
* ofd_grant_statfs(), from which we withdraw the space already granted to
* clients and the reserved space.
+ * Caller must hold ofd_grant_lock spinlock.
*
- * \param exp - export which received the write request
+ * \param[in] exp export associated with the device for which the amount
+ * of available space is requested
+ * \retval amount of non-allocated space, in bytes
*/
static obd_size ofd_grant_space_left(struct obd_export *exp)
{
struct obd_device *obd = exp->exp_obd;
struct ofd_device *ofd = ofd_exp(exp);
obd_size tot_granted;
- obd_size left, avail;
+ obd_size left;
+ obd_size avail;
obd_size unstable;
ENTRY;
}
/**
+ * Process grant information from obdo structure packed in incoming BRW
+ *
* Grab the dirty and seen grant announcements from the incoming obdo.
* We will later calculate the client's new grant and return it.
* Caller must hold ofd_grant_lock spinlock.
*
- * \param env - is the lu environment supplying osfs storage
- * \param exp - is the export for which we received the request
- * \paral oa - is the incoming obdo sent by the client
+ * \param[in] env LU environment supplying osfs storage
+ * \param[in] exp export for which we received the request
+ * \param[in,out] oa incoming obdo sent by the client
+ *
*/
static void ofd_grant_incoming(const struct lu_env *env, struct obd_export *exp,
struct obdo *oa)
struct filter_export_data *fed;
struct ofd_device *ofd = ofd_exp(exp);
struct obd_device *obd = exp->exp_obd;
- long dirty, dropped, grant_chunk;
+ long dirty;
+ long dropped;
+ long grant_chunk;
ENTRY;
assert_spin_locked(&ofd->ofd_grant_lock);
}
/**
- * Called when the client is able to release some grants. Proceed with the
- * shrink request when there is less ungranted space remaining
- * than the amount all of the connected clients would consume if they
- * used their full grant.
+ * Grant shrink request handler.
+ *
+ * Client nodes can explicitly release grant space (i.e. process called grant
+ * shrinking). This function proceeds with the shrink request when there is
+ * less ungranted space remaining than the amount all of the connected clients
+ * would consume if they used their full grant.
+ * Caller must hold ofd_grant_lock spinlock.
*
- * \param exp - is the export for which we received the request
- * \paral oa - is the incoming obdo sent by the client
- * \param left_space - is the remaining free space with space already granted
- * taken out
+ * \param[in] exp export releasing grant space
+ * \param[in,out] oa incoming obdo sent by the client
+ * \param[in] left_space remaining free space with space already granted
+ * taken out
*/
-static void ofd_grant_shrink(struct obd_export *exp,
- struct obdo *oa, obd_size left_space)
+static void ofd_grant_shrink(struct obd_export *exp, struct obdo *oa,
+ obd_size left_space)
{
struct filter_export_data *fed;
struct ofd_device *ofd = ofd_exp(exp);
/**
* Calculate how much space is required to write a given network buffer
+ *
+ * This function takes block alignment into account to estimate how much on-disk
+ * space will be required to successfully write the whole niobuf.
+ * Estimated space is inflated if the export does not support
+ * OBD_CONNECT_GRANT_PARAM and if the backend filesystem has a block size
+ * larger than the minimal supported page size (i.e. 4KB).
+ *
+ * \param[in] exp export associated which the write request
+ * \param[in] ofd ofd device handling the request
+ * \param[in] rnb network buffer to estimate size of
+ *
+ * \retval space (in bytes) that will be consumed to write the
+ * network buffer
*/
static inline int ofd_grant_rnb_size(struct obd_export *exp,
struct ofd_device *ofd,
struct niobuf_remote *rnb)
{
- obd_size blocksize, bytes, end;
+ obd_size blocksize;
+ obd_size bytes;
+ obd_size end;
if (exp && ofd_grant_compat(exp, ofd))
blocksize = 1ULL << COMPAT_BSIZE_SHIFT;
return bytes;
}
-
/**
+ * Validate grant accounting for each incoming remote network buffer.
+ *
* When clients have dirtied as much space as they've been granted they
- * fall through to sync writes. These sync writes haven't been expressed
+ * fall through to sync writes. These sync writes haven't been expressed
* in grants and need to error with ENOSPC when there isn't room in the
- * filesystem for them after grants are taken into account. However,
+ * filesystem for them after grants are taken into account. However,
* writeback of the dirty data that was already granted space can write
* right on through.
+ * The OBD_BRW_GRANTED flag will be set in the rnb_flags of each network
+ * buffer which has been granted enough space to proceed. Buffers without
+ * this flag will fail to be written with -ENOSPC (see ofd_preprw_write().
* Caller must hold ofd_grant_lock spinlock.
*
- * \param env - is the lu environment passed by the caller
- * \param exp - is the export identifying the client which sent the RPC
- * \param oa - is the incoming obdo in which we should return the pack the
- * additional grant
- * \param rnb - is the list of network buffers
- * \param niocont - is the number of network buffers in the list
- * \param left - is the remaining free space with space already granted
- * taken out
+ * \param[in] env LU environment passed by the caller
+ * \param[in] exp export identifying the client which sent the RPC
+ * \param[in] oa incoming obdo in which we should return the pack the
+ * additional grant
+ * \param[in,out] rnb the list of network buffers
+ * \param[in] niocont the number of network buffers in the list
+ * \param[in] left the remaining free space with space already granted
+ * taken out
*/
static void ofd_grant_check(const struct lu_env *env, struct obd_export *exp,
struct obdo *oa, struct niobuf_remote *rnb,
}
/**
+ * Allocate additional grant space to a client
+ *
* Calculate how much grant space to return to client, based on how much space
* is currently free and how much of that is already granted.
* Caller must hold ofd_grant_lock spinlock.
*
- * \param exp - is the export of the client which sent the request
- * \param curgrant - is the current grant claimed by the client
- * \param want - is how much grant space the client would like to have
- * \param left - is the remaining free space with granted space taken out
- * \param conservative - is how server grants, if true, a certain amount, else
- * server will grant as client requested.
+ * \param[in] exp export of the client which sent the request
+ * \param[in] curgrant current grant claimed by the client
+ * \param[in] want how much grant space the client would like to
+ * have
+ * \param[in] left remaining free space with granted space taken
+ * out
+ * \param[in] conservative if set to true, the server should be cautious
+ * and limit how much space is granted back to the
+ * client. Otherwise, the server should try hard to
+ * satisfy the client request.
+ *
+ * \retval amount of grant space allocated
*/
-static long ofd_grant(struct obd_export *exp, obd_size curgrant,
- obd_size want, obd_size left, bool conservative)
+static long ofd_grant_alloc(struct obd_export *exp, obd_size curgrant,
+ obd_size want, obd_size left, bool conservative)
{
struct obd_device *obd = exp->exp_obd;
struct ofd_device *ofd = ofd_exp(exp);
}
/**
- * Client connection or reconnection.
+ * Handle grant space allocation on client connection & reconnection.
*
- * \param env - is the lu environment provided by the caller
- * \param exp - is the client's export which is reconnecting
- * \param want - is how much the client would like to get
- * \param conservative - is how server grants to client, if true server will
- * only grant certain amount, else server will grant client requested
- * amount.
+ * A new non-readonly connection gets an initial grant allocation equals to
+ * ofd_grant_chunk() (i.e. twice the max BRW size in most of the cases).
+ * On reconnection, grant counters between client & OST are resynchronized
+ * and additional space might be granted back if possible.
+ *
+ * \param[in] env LU environment provided by the caller
+ * \param[in] exp client's export which is (re)connecting
+ * \param[in] want how much grant space the client would like to get
+ * \param[in] new_conn must set to true if this is a new connection and false
+ * for a reconnection
+ *
+ * \retval amount of grant space currently owned by the client
*/
long ofd_grant_connect(const struct lu_env *env, struct obd_export *exp,
- obd_size want, bool conservative)
+ obd_size want, bool new_conn)
{
struct ofd_device *ofd = ofd_exp(exp);
struct filter_export_data *fed = &exp->exp_filter_data;
goto refresh;
}
- ofd_grant(exp, ofd_grant_to_cli(exp, ofd, (obd_size)fed->fed_grant),
- want, left, conservative);
+ ofd_grant_alloc(exp,
+ ofd_grant_to_cli(exp, ofd, (obd_size)fed->fed_grant),
+ want, left, new_conn);
/* return to client its current grant */
grant = ofd_grant_to_cli(exp, ofd, (obd_size)fed->fed_grant);
}
/**
+ * Release all grant space attached to a given export.
+ *
* Remove a client from the grant accounting totals. We also remove
* the export from the obd device under the osfs and dev locks to ensure
* that the ofd_grant_sanity_check() calculations are always valid.
* The client should do something similar when it invalidates its import.
*
- * \param exp - is the client's export to remove from grant accounting
+ * \param[in] exp client's export to remove from grant accounting
*/
void ofd_grant_discard(struct obd_export *exp)
{
}
/**
- * Called at prepare time when handling read request. This function extracts
- * incoming grant information from the obdo and processes the grant shrink
- * request, if any.
+ * Process grant information from incoming bulk read request.
+ *
+ * Extract grant information packed in obdo structure (OBD_MD_FLGRANT set in
+ * o_valid). Bulk reads usually comes with grant announcements (number of dirty
+ * blocks, remaining amount of grant space, ...) and could also include a grant
+ * shrink request. Unlike bulk write, no additional grant space is returned on
+ * bulk read request.
*
- * \param env - is the lu environment provided by the caller
- * \param exp - is the export of the client which sent the request
- * \paral oa - is the incoming obdo sent by the client
+ * \param[in] env is the lu environment provided by the caller
+ * \param[in] exp is the export of the client which sent the request
+ * \paral[in,out] oa is the incoming obdo sent by the client
*/
void ofd_grant_prepare_read(const struct lu_env *env,
struct obd_export *exp, struct obdo *oa)
}
/**
- * Called at write prepare time to handle incoming grant, check that we have
- * enough space and grant some space back to the client if possible.
+ * Process grant information from incoming bulk write request.
*
- * \param env - is the lu environment provided by the caller
- * \param exp - is the export of the client which sent the request
- * \paral oa - is the incoming obdo sent by the client
- * \param rnb - is the list of network buffers
- * \param niocont - is the number of network buffers in the list
+ * This function extracts client's grant announcements from incoming bulk write
+ * request and attempts to allocate grant space for network buffers that need it
+ * (i.e. OBD_BRW_FROM_GRANT not set in rnb_fags).
+ * Network buffers which aren't granted the OBD_BRW_GRANTED flag should not
+ * proceed further and should fail with -ENOSPC.
+ * Whenever possible, additional grant space will be returned to the client
+ * in the bulk write reply.
+ * ofd_grant_prepare_write() must be called before writting any buffers to
+ * the backend storage. This function works in pair with ofd_grant_commit()
+ * which must be invoked once all buffers have been written to disk in order
+ * to release space from the pending grant counter.
+ *
+ * \param[in] env LU environment provided by the caller
+ * \param[in] exp export of the client which sent the request
+ * \param[in] oa incoming obdo sent by the client
+ * \param[in] rnb list of network buffers
+ * \param[in] niocont number of network buffers in the list
*/
void ofd_grant_prepare_write(const struct lu_env *env,
struct obd_export *exp, struct obdo *oa,
ofd_grant_shrink(exp, oa, left);
else
/* grant more space back to the client if possible */
- oa->o_grant = ofd_grant(exp, oa->o_grant, oa->o_undirty, left,
- true);
+ oa->o_grant = ofd_grant_alloc(exp, oa->o_grant, oa->o_undirty,
+ left, true);
spin_unlock(&ofd->ofd_grant_lock);
}
/**
- * Called during object precreation to consume grant space.
- * More space is granted for precreation if possible.
+ * Consume grant space reserved for object creation.
+ *
+ * Grant space is allocated to the local self export for object precreation.
+ * This is required to prevent object precreation from consuming grant space
+ * allocated to client nodes for the data writeback cache.
+ * This function consumes enough space to create \a nr objects and allocates
+ * more grant space to the self export for future precreation requests, if
+ * possible.
*
- * \param env - is the lu environment provided by the caller
- * \param exp - is the export holding the grant space for precreation (= self
- * export currently)
- * \paral nr - is the number of objects the caller wants to create objects
+ * \param[in] env LU environment provided by the caller
+ * \param[in] exp export holding the grant space for precreation (= self
+ * export currently)
+ * \param[in] nr number of objects to be created
+ *
+ * \retval 0 for success
+ * \retval -ENOSPC on failure
*/
int ofd_grant_create(const struct lu_env *env, struct obd_export *exp, int *nr)
{
/* always try to book enough space to handle a large precreate
* request */
wanted -= fed->fed_grant;
- ofd_grant(exp, fed->fed_grant, wanted, left, false);
+ ofd_grant_alloc(exp, fed->fed_grant, wanted, left, false);
}
spin_unlock(&ofd->ofd_grant_lock);
RETURN(0);
}
/**
- * Called at commit time to update pending grant counter for writes in flight
+ * Release grant space added to the pending counter by ofd_grant_prepare_write()
+ *
+ * Update pending grant counter once buffers have been written to the disk.
*
- * \param env - is the lu environment provided by the caller
- * \param exp - is the export of the client which sent the request
+ * \param[in] env LU environment provided by the caller
+ * \param[in] exp export of the client which sent the request
*/
void ofd_grant_commit(const struct lu_env *env, struct obd_export *exp,
int rc)
git://git.whamcloud.com / fs / lustre-release.git / commitdiff