1 .\" Copyright (c) 2003 Poul-Henning Kamp
2 .\" Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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36 .Nm geom_stats_close ,
37 .Nm geom_stats_resync ,
38 .Nm geom_stats_snapshot_get ,
39 .Nm geom_stats_snapshot_free ,
40 .Nm geom_stats_snapshot_timestamp ,
41 .Nm geom_stats_snapshot_reset ,
42 .Nm geom_stats_snapshot_next ,
62 .Nd userland API library for kernel GEOM subsystem
67 .Ss "Statistics Functions"
69 .Fn geom_stats_close void
71 .Fn geom_stats_open void
73 .Fn geom_stats_resync void
75 .Fn geom_stats_snapshot_get void
77 .Fn geom_stats_snapshot_free "void *arg"
79 .Fn geom_stats_snapshot_timestamp "void *arg" "struct timespec *tp"
81 .Fn geom_stats_snapshot_reset "void *arg"
82 .Ft "struct devstat *"
83 .Fn geom_stats_snapshot_next "void *arg"
84 .Ss "Control Functions"
85 .Ft "struct gctl_req *"
86 .Fn gctl_get_handle "void"
88 .Fn gctl_ro_param "struct gctl_req *req" "const char *name" "int len" "const void *value"
90 .Fn gctl_rw_param "struct gctl_req *req" "const char *name" "int len" "void *value"
92 .Fn gctl_issue "struct gctl_req *req"
94 .Fn gctl_free "struct gctl_req *req"
96 .Fn gctl_dump "struct gctl_req *req" "FILE *f"
97 .Ss "Utility Functions"
99 .Fn g_open "const char *name" "int dowrite"
103 .Fn g_mediasize "int fd"
105 .Fn g_sectorsize "int fd"
107 .Fn g_stripeoffset "int fd"
109 .Fn g_stripesize "int fd"
113 .Fn g_delete "int fd" "off_t offset" "off_t length"
115 .Fn g_device_path "const char *devpath"
117 .Fn g_get_ident "int fd" "char *ident" "size_t size"
119 .Fn g_get_name "const char *ident" "char *name" "size_t size"
121 .Fn g_open_by_ident "const char *ident" "int dowrite" "char *name" "size_t size"
123 .Fn g_providername "int fd"
127 library contains the official and publicized API for
128 interacting with the GEOM subsystem in the kernel.
129 .Ss "Statistics Functions"
130 GEOM collects statistics data for all consumers and providers, but does
131 not perform any normalization or presentation on the raw data, this is
132 left as an exercise for user-land presentation utilities.
138 functions open and close the necessary pathways to access the raw
139 statistics information in the kernel.
140 These functions are likely to
141 open one or more files and cache the file descriptors locally.
144 function returns zero on success, and sets
149 .Fn geom_stats_resync
150 function will check if more statistics collection points have been
151 added in the kernel since
153 or the previous call to
154 .Fn geom_stats_resync .
157 .Fn geom_stats_snapshot_get
159 will acquire a snapshot of the raw data from the kernel, and while a
160 reasonable effort is made to make this snapshot as atomic and consistent
161 as possible, no guarantee is given that it will actually be so.
162 The snapshot must be freed again using the
163 .Fn geom_stats_snapshot_free
166 .Fn geom_stats_snapshot_get
172 .Fn geom_stats_snapshot_timestamp
174 provides access to the timestamp acquired in the snapshot.
177 .Fn geom_stats_snapshot_reset
179 .Fn geom_stats_snapshot_next
181 provide an iterator over the statistics slots in the snapshot.
183 .Fn geom_stats_snapshot_reset
185 forces the internal pointer in the snapshot back to before the first item.
187 .Fn geom_stats_snapshot_next
189 returns the next item, and
191 if there are no more items in the snapshot.
192 .Ss "Control Functions"
195 functions are used to send requests to GEOM classes.
197 class to actually be able to receive these requests, it must have defined a
201 .Vt "struct gctl_req *" ,
203 .Fn gctl_get_handle ,
204 can hold any number of parameters, which must be added to it with
206 (for read-only parameters) or
208 (for read/write parameters).
216 which is used to identify the parameter, and a
218 which contains, in the read-only case, the data to be passed to the
219 GEOM class, or, in the read/write case, a pointer to preallocated memory
220 that the GEOM class should fill with the desired data.
223 is negative, it is assumed that
227 string and the actual length is taken from the string length of
229 otherwise it must hold the size of
234 containing the string
236 is mandatory for each request, and the
239 must hold the name of the GEOM class where the request should be sent to.
241 Also mandatory for each request is a parameter with a
245 and the corresponding
247 needs to hold the command string that the GEOM class should react upon.
249 Once all desired parameters are filled in, the request must be sent to
250 the GEOM subsystem with
254 on success, or a string containing the error message
257 After the request is finished, the allocated memory should be released with
263 can be used to format the contents of
265 to the open file handle pointed to by
267 for debugging purposes.
269 Error handling for the control functions is postponed until the call
274 on success, or an error message corresponding to the
275 first error which happened.
276 .Ss "Utility Functions"
279 functions are used to communicate with GEOM providers.
283 function opens the given provider and returns file descriptor number, which can
284 be used with other functions.
287 argument indicates if operations that modify the provider (like
291 are going to be called.
295 function closes the provider.
299 function returns size of the given provider.
303 function returns sector size of the given provider.
307 function returns stripe offset of the given provider.
311 function returns stripe size of the given provider.
317 request to flush write cache of the provider.
321 function tells the provider that the given data range is no longer used.
325 function returns the full path to a provider given a partial or full path to the
327 If the device can not be found or is not a valid geom provider, NULL is
332 function returns provider's fixed and unique identifier.
335 argument should be at least
341 function returns name of the provider, which identifier is equal to the
347 function opens provider using its ident, unlike
349 which uses provider's name.
354 the function will store provider's name there.
358 function returns the provider name of an open file descriptor.
359 If the file descriptor does not point to a valid geom provider, NULL is
366 return a value greater than or equal to
372 Create a request that is to be sent to the CCD class, and tell
373 it to destroy a specific geom:
374 .Bd -literal -offset indent
375 H = gctl_get_handle();
376 gctl_ro_param(H, "verb", -1, "destroy geom");
377 gctl_ro_param(H, "class", -1, "CCD");
378 sprintf(buf, "ccd%d", ccd);
379 gctl_ro_param(H, "geom", -1, buf);
380 errstr = gctl_issue(H);
382 err(1, "could not destroy ccd: %s", errstr);
391 .An Poul-Henning Kamp Aq Mt phk@FreeBSD.org
392 .An Lukas Ertl Aq Mt le@FreeBSD.org
393 .An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org