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9p: Use a slab for allocating requests

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Replace the custom batch allocation with a slab.  Use an IDR to store
pointers to the active requests instead of an array.  We don't try to
handle P9_NOTAG specially; the IDR will happily shrink all the way back
once the TVERSION call has completed.

Link: http://lkml.kernel.org/r/20180711210225.19730-6-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
This commit is contained in:
Matthew Wilcox
2018-07-11 14:02:24 -07:00
committed by Dominique Martinet
parent 62e3941776
commit 996d5b4db4
3 changed files with 102 additions and 196 deletions
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51
include/net/9p/client.h
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@@ -64,22 +64,15 @@ enum p9_trans_status {
/**
* enum p9_req_status_t - status of a request
* @REQ_STATUS_IDLE: request slot unused
* @REQ_STATUS_ALLOC: request has been allocated but not sent
* @REQ_STATUS_UNSENT: request waiting to be sent
* @REQ_STATUS_SENT: request sent to server
* @REQ_STATUS_RCVD: response received from server
* @REQ_STATUS_FLSHD: request has been flushed
* @REQ_STATUS_ERROR: request encountered an error on the client side
*
* The @REQ_STATUS_IDLE state is used to mark a request slot as unused
* but use is actually tracked by the idpool structure which handles tag
* id allocation.
*
*/
enum p9_req_status_t {
REQ_STATUS_IDLE,
REQ_STATUS_ALLOC,
REQ_STATUS_UNSENT,
REQ_STATUS_SENT,
@@ -92,24 +85,12 @@ enum p9_req_status_t {
* struct p9_req_t - request slots
* @status: status of this request slot
* @t_err: transport error
* @flush_tag: tag of request being flushed (for flush requests)
* @wq: wait_queue for the client to block on for this request
* @tc: the request fcall structure
* @rc: the response fcall structure
* @aux: transport specific data (provided for trans_fd migration)
* @req_list: link for higher level objects to chain requests
*
* Transport use an array to track outstanding requests
* instead of a list. While this may incurr overhead during initial
* allocation or expansion, it makes request lookup much easier as the
* tag id is a index into an array. (We use tag+1 so that we can accommodate
* the -1 tag for the T_VERSION request).
* This also has the nice effect of only having to allocate wait_queues
* once, instead of constantly allocating and freeing them. Its possible
* other resources could benefit from this scheme as well.
*
*/
struct p9_req_t {
int status;
int t_err;
@@ -117,40 +98,26 @@ struct p9_req_t {
struct p9_fcall *tc;
struct p9_fcall *rc;
void *aux;
struct list_head req_list;
};
/**
* struct p9_client - per client instance state
* @lock: protect @fidlist
* @lock: protect @fids and @reqs
* @msize: maximum data size negotiated by protocol
* @dotu: extension flags negotiated by protocol
* @proto_version: 9P protocol version to use
* @trans_mod: module API instantiated with this client
* @status: connection state
* @trans: tranport instance state and API
* @fids: All active FID handles
* @tagpool - transaction id accounting for session
* @reqs - 2D array of requests
* @max_tag - current maximum tag id allocated
* @name - node name used as client id
* @reqs: All active requests.
* @name: node name used as client id
*
* The client structure is used to keep track of various per-client
* state that has been instantiated.
* In order to minimize per-transaction overhead we use a
* simple array to lookup requests instead of a hash table
* or linked list. In order to support larger number of
* transactions, we make this a 2D array, allocating new rows
* when we need to grow the total number of the transactions.
*
* Each row is 256 requests and we'll support up to 256 rows for
* a total of 64k concurrent requests per session.
*
* Bugs: duplicated data and potentially unnecessary elements.
*/
struct p9_client {
spinlock_t lock; /* protect client structure */
spinlock_t lock;
unsigned int msize;
unsigned char proto_version;
struct p9_trans_module *trans_mod;
@@ -170,10 +137,7 @@ struct p9_client {
} trans_opts;
struct idr fids;
struct p9_idpool *tagpool;
struct p9_req_t *reqs[P9_ROW_MAXTAG];
int max_tag;
struct idr reqs;
char name[__NEW_UTS_LEN + 1];
};
@@ -279,4 +243,7 @@ struct p9_fid *p9_client_xattrwalk(struct p9_fid *, const char *, u64 *);
int p9_client_xattrcreate(struct p9_fid *, const char *, u64, int);
int p9_client_readlink(struct p9_fid *fid, char **target);
int p9_client_init(void);
void p9_client_exit(void);
#endif /* NET_9P_CLIENT_H */