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path: root/drivers/block/rbd.c
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* rbd: rename __rbd_init_snaps_header()Alex Elder2012-10-01
| | | | | | | | | | | | | | | The name __rbd_init_snaps_header() doesn't really convey what that function does very well. Its purpose is to scan a new snapshot context and either create or destroy snapshot device entries so that local host's view is consistent with the reality maintained on the OSDs. This patch just changes the name of this function, to be rbd_dev_snap_devs_update(). Still not perfect, but I think better. Also add some dynamic debug statements to this function. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: rename rbd_id_get()Alex Elder2012-10-01
| | | | | | | | | | | | | | | | | | This should have been done as part of this commit: commit de71a2970d57463d3d965025e33ec3adcf391248 Author: Alex Elder <elder@inktank.com> Date: Tue Jul 3 16:01:19 2012 -0500 rbd: rename rbd_device->id rbd_id_get() is assigning the rbd_dev->dev_id field. Change the name of that function as well as rbd_id_put() and rbd_id_max to reflect what they are affecting. Add some dynamic debug statements related to rbd device id activity. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: define rbd_assert()Alex Elder2012-10-01
| | | | | | | | | Define rbd_assert() and use it in place of various BUG_ON() calls now present in the code. By default assertion checking is enabled; we want to do this differently at some point. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: split up rbd_get_segment()Alex Elder2012-10-01
| | | | | | | | | | | | | | | | | | | | | | | | | There are two places where rbd_get_segment() is called. One, in rbd_rq_fn(), only needs to know the length within a segment that an I/O request should be. The other, in rbd_do_op(), also needs the name of the object and the offset within it for the I/O request. Split out rbd_segment_name() into three dedicated functions: - rbd_segment_name() allocates and formats the name of the object for a segment containing a given rbd image offset - rbd_segment_offset() computes the offset within a segment for a given rbd image offset - rbd_segment_length() computes the length to use for I/O within a segment for a request, not to exceed the end of a segment object. In the new functions be a bit more careful, checking for possible error conditions: - watch for errors or overflows returned by snprintf() - catch (using BUG_ON()) potential overflow conditions when computing segment length Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: check for overflow in rbd_get_num_segments()Alex Elder2012-10-01
| | | | | | | | | | | | | | | | | | | | | It is possible in rbd_get_num_segments() for an overflow to occur when adding the offset and length. This is easily avoided. Since the function returns an int and the one caller is already prepared to handle errors, have it return -ERANGE if overflow would occur. The overflow check would not work if a zero-length request was being tested, so short-circuit that case, returning 0 for the number of segments required. (This condition might be avoided elsewhere already, I don't know.) Have the caller end the request if either an error or 0 is returned. The returned value is passed to __blk_end_request_all(), meaning a 0 length request is not treated an error. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: drop needless test in rbd_rq_fn()Alex Elder2012-10-01
| | | | | | | | | There's a test for null rq pointer inside the while loop in rbd_rq_fn() that's not needed. That same test already occurred in the immediatly preceding loop condition test. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: bio_chain_clone() cleanupsAlex Elder2012-10-01
| | | | | | | | | | | | | | | | | | In bio_chain_clone(), at the end of the function the bi_next field of the tail of the new bio chain is nulled. This isn't necessary, because if "tail" is non-null, its value will be the last bio structure allocated at the top of the while loop in that function. And before that structure is added to the end of the new chain, its bi_next pointer is always made null. While touching that function, clean a few other things: - define each local variable on its own line - move the definition of "tmp" to an inner scope - move the modification of gfpmask closer to where it's used - rearrange the logic that sets the chain's tail pointer Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: kill notify_timeout optionAlex Elder2012-10-01
| | | | | | | | The "notify_timeout" rbd device option is never used, so get rid of it. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: add read_only rbd map optionAlex Elder2012-10-01
| | | | | | | | | | Add the ability to map an rbd image read-only, by specifying either "read_only" or "ro" as an option on the rbd "command line." Also allow the inverse to be explicitly specified using "read_write" or "rw". Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: move rbd_opts to struct rbd_deviceAlex Elder2012-10-01
| | | | | | | | | | | | | The rbd options don't really apply to the ceph client. So don't store a pointer to it in the ceph_client structure, and put them (a struct, not a pointer) into the rbd_dev structure proper. Pass the rbd device structure to rbd_client_create() so it can assign rbd_dev->rbdc if successful, and have it return an error code instead of the rbd client pointer. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: more cleanup in rbd_header_from_disk()Alex Elder2012-10-01
| | | | | | | | | | This just rearranges things a bit more in rbd_header_from_disk() so that the snapshot sizes are initialized right after the buffer to hold them is allocated and doing a little further consolidation that follows from that. Also adds a few simple comments. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: kill incore snap_names_lenAlex Elder2012-10-01
| | | | | | | | | | | | | | | | The only thing the on-disk snap_names_len field is needed is to size the buffer allocated to hold a copy of the snapshot names for an rbd image. So don't bother saving it in the in-core rbd_image_header structure. Just use a local variable to hold the required buffer size while it's needed. Move the code that actually copies the snapshot names up closer to where the required length is saved. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: don't over-allocate space for object prefixAlex Elder2012-10-01
| | | | | | | | | | | In rbd_header_from_disk() the object prefix buffer is sized based on the maximum size it's block_name equivalent on disk could be. Instead, only allocate enough to hold null-terminated string from the on-disk header--or the maximum size of no NUL is found. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: handle locking inside __rbd_client_find()Alex Elder2012-10-01
| | | | | | | | | | | | | | There is only caller of __rbd_client_find(), and it somewhat clumsily gets the appropriate lock and gets a reference to the existing ceph_client structure if it's found. Instead, have that function handle its own locking, and acquire the reference if found while it holds the lock. Drop the underscores from the name because there's no need to signify anything special about this function. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
* rbd: add new snapshots at the tailAlex Elder2012-10-01
| | | | | | | | | | | | | | | | | | | | | | This fixes a bug that went in with this commit: commit f6e0c99092cca7be00fca4080cfc7081739ca544 Author: Alex Elder <elder@inktank.com> Date: Thu Aug 2 11:29:46 2012 -0500 rbd: simplify __rbd_init_snaps_header() The problem is that a new rbd snapshot needs to go either after an existing snapshot entry, or at the *end* of an rbd device's snapshot list. As originally coded, it is placed at the beginning. This was based on the assumption the list would be empty (so it wouldn't matter), but in fact if multiple new snapshots are added to an empty list in one shot the list will be non-empty after the first one is added. This addresses http://tracker.newdream.net/issues/3063 Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: rename block_name -> object_prefixAlex Elder2012-10-01
| | | | | | | | | | | | | | | | In the on-disk image header structure there is a field "block_name" which represents what we now call the "object prefix" for an rbd image. Rename this field "object_prefix" to be consistent with modern usage. This appears to be the only remaining vestige of the use of "block" in symbols that represent objects in the rbd code. This addresses http://tracker.newdream.net/issues/1761 Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com> Reviewed-by: Dan Mick <dan.mick@inktank.com>
* rbd: separate reading header from decoding itAlex Elder2012-10-01
| | | | | | | | | | | | | | Right now rbd_read_header() both reads the header object for an rbd image and decodes its contents. It does this repeatedly if needed, in order to ensure a complete and intact header is obtained. Separate this process into two steps--reading of the raw header data (in new function, rbd_dev_v1_header_read()) and separately decoding its contents (in rbd_header_from_disk()). As a result, the latter function no longer requires its allocated_snaps argument. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: expand rbd_dev_ondisk_valid() checksAlex Elder2012-10-01
| | | | | | | | | Add checks on the validity of the snap_count and snap_names_len field values in rbd_dev_ondisk_valid(). This eliminates the need to do them in rbd_header_from_disk(). Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: return earlier in rbd_header_from_disk()Alex Elder2012-10-01
| | | | | | | | | | | | | | | | | | | | | | | | | The only caller of rbd_header_from_disk() is rbd_read_header(). It passes as allocated_snaps the number of snapshots it will have received from the server for the snapshot context that rbd_header_from_disk() is to interpret. The first time through it provides 0--mainly to extract the number of snapshots from the snapshot context header--so that it can allocate an appropriately-sized buffer to receive the entire snapshot context from the server in a second request. rbd_header_from_disk() will not fill in the array of snapshot ids unless the number in the snapshot matches the number the caller had allocated. This patch adjusts that logic a little further to be more efficient. rbd_read_header() doesn't even examine the snapshot context unless the snapshot count (stored in header->total_snaps) matches the number of snapshots allocated. So rbd_header_from_disk() doesn't need to allocate or fill in the snapshot context field at all in that case. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: rearrange rbd_header_from_disk()Alex Elder2012-10-01
| | | | | | | | | | | | | | This just moves code around for the most part. It was pulled out as a separate patch to avoid cluttering up some upcoming patches which are more substantive. The point is basically to group everything related to initializing the snapshot context together. The only functional change is that rbd_header_from_disk() now ensures the (in-core) header it is passed is zero-filled. This allows a simpler error handling path in rbd_header_from_disk(). Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: use sizeof (object) instead of sizeof (type)Alex Elder2012-10-01
| | | | | | | | | Fix a few spots in rbd_header_from_disk() to use sizeof (object) rather than sizeof (type). Use a local variable to record sizes to shorten some lines and improve readability. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: ensure invalid pointers are made nullAlex Elder2012-10-01
| | | | | | | | | | | Fix a number of spots where a pointer value that is known to have become invalid but was not reset to null. Also, toss in a change so we use sizeof (object) rather than sizeof (type). Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: make snap_names_len a u64Alex Elder2012-10-01
| | | | | | | | | | The snap_names_len field of an rbd_image_header structure is defined with type size_t. That field is used as both the source and target of 64-bit byte-order swapping operations though, so it's best to define it with type u64 instead. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: simplify __rbd_init_snaps_header()Alex Elder2012-10-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The purpose of __rbd_init_snaps_header() is to compare a new snapshot context with an rbd device's list of existing snapshots. It updates the list by adding any new snapshots or removing any that are not present in the new snapshot context. The code as written is a little confusing, because it traverses both the existing snapshot list and the set of snapshots in the snapshot context in reverse. This was done based on an assumption about snapshots that is not true--namely that a duplicate snapshot name could cause an error in intepreting things if they were not processed in ascending order. These precautions are not necessary, because: - all snapshots are uniquely identified by their snapshot id - a new snapshot cannot be created if the rbd device has another snapshot with the same name (It is furthermore not currently possible to rename a snapshot.) This patch re-implements __rbd_init_snaps_header() so it passes through both the existing snapshot list and the entries in the snapshot context in forward order. It still does the same thing as before, but I find the logic considerably easier to understand. By going forward through the names in the snapshot context, there is no longer a need for the rbd_prev_snap_name() helper function. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: drop dev reference on error in rbd_open()Alex Elder2012-09-21
| | | | | | | | | | | If a read-only rbd device is opened for writing in rbd_open(), it returns without dropping the just-acquired device reference. Fix this by moving the read-only check before getting the reference. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Yehuda Sadeh <yehuda@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: create rbd_refresh_helper()Alex Elder2012-07-30
| | | | | | | | Create a simple helper that handles the common case of calling __rbd_refresh_header() while holding the ctl_mutex. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: return obj version in __rbd_refresh_header()Alex Elder2012-07-30
| | | | | | | | | | | Add a new parameter to __rbd_refresh_header() through which the version of the header object is passed back to the caller. In most cases this isn't needed. The main motivation is to normalize (almost) all calls to __rbd_refresh_header() so they are all wrapped immediately by mutex_lock()/mutex_unlock(). Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: fixes in rbd_header_from_disk()Alex Elder2012-07-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | This fixes a few issues in rbd_header_from_disk(): - There is a check intended to catch overflow, but it's wrong in two ways. - First, the type we don't want to overflow is size_t, not unsigned int, and there is now a SIZE_MAX we can use for use with that type. - Second, we're allocating the snapshot ids and snapshot image sizes separately (each has type u64; on disk they grouped together as a rbd_image_header_ondisk structure). So we can use the size of u64 in this overflow check. - If there are no snapshots, then there should be no snapshot names. Enforce this, and issue a warning if we encounter a header with no snapshots but a non-zero snap_names_len. - When saving the snapshot names into the header, be more direct in defining the offset in the on-disk structure from which they're being copied by using "snap_count" rather than "i" in the array index. - If an error occurs, the "snapc" and "snap_names" fields are freed at the end of the function. Make those fields be null pointers after they're freed, to be explicit that they are no longer valid. - Finally, move the definition of the local variable "i" to the innermost scope in which it's needed. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: always pass ops array to rbd_req_sync_op()Alex Elder2012-07-30
| | | | | | | | | | | | | | | | | All of the callers of rbd_req_sync_op() except one pass a non-null "ops" pointer. The only one that does not is rbd_req_sync_read(), which passes CEPH_OSD_OP_READ as its "opcode" and, CEPH_OSD_FLAG_READ for "flags". By allocating the ops array in rbd_req_sync_read() and moving the special case code for the null ops pointer into it, it becomes clear that much of that code is not even necessary. In addition, the "opcode" argument to rbd_req_sync_op() is never actually used, so get rid of that. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: pass null version pointer in add_snap()Alex Elder2012-07-30
| | | | | | | | | rbd_header_add_snap() passes the address of a version variable to rbd_req_sync_exec(), but it ignores the result. Just pass a null pointer instead. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: make rbd_create_rw_ops() return a pointerAlex Elder2012-07-30
| | | | | | | | | | Either rbd_create_rw_ops() will succeed, or it will fail because a memory allocation failed. Have it just return a valid pointer or null rather than stuffing a pointer into a provided address and returning an errno. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: have __rbd_add_snap_dev() return a pointerAlex Elder2012-07-30
| | | | | | | | | | It's not obvious whether the snapshot pointer whose address is provided to __rbd_add_snap_dev() will be assigned by that function. Change it to return the snapshot, or a pointer-coded errno in the event of a failure. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: drop "object_name" from rbd_req_sync_unwatch()Alex Elder2012-07-30
| | | | | | | | | rbd_req_sync_unwatch() only ever uses rbd_dev->header_name as the value of its "object_name" parameter, and that value is available within the function already. So get rid of the parameter. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: drop "object_name" from rbd_req_sync_notify_ack()Alex Elder2012-07-30
| | | | | | | | | rbd_req_sync_notify_ack() only ever uses rbd_dev->header_name as the value of its "object_name" parameter, and that value is available within the function already. So get rid of the parameter. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: drop "object_name" from rbd_req_sync_notify()Alex Elder2012-07-30
| | | | | | | | | rbd_req_sync_notify() only ever uses rbd_dev->header_name as the value of its "object_name" parameter, and that value is available within the function already. So get rid of the parameter. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: drop "object_name" from rbd_req_sync_watch()Alex Elder2012-07-30
| | | | | | | | | | | | | | | rbd_req_sync_watch() is only called in one place, and in that place it passes rbd_dev->header_name as the value of the "object_name" parameter. This value is available within the function already. Having the extra parameter leaves the impression the object name could take on different values, but it does not. So get rid of the parameter. We can always add it back again if we find we want to watch some other object in the future. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: drop rbd_dev parameter in snap functionsAlex Elder2012-07-30
| | | | | | | | Both rbd_register_snap_dev() and __rbd_remove_snap_dev() have rbd_dev parameters that are unused. Remove them. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: drop rbd_header_from_disk() gfp_flags parameterAlex Elder2012-07-30
| | | | | | | | | | | | The function rbd_header_from_disk() is only called in one spot, and it passes GFP_KERNEL as its value for the gfp_flags parameter. Just drop that parameter and substitute GFP_KERNEL everywhere within that function it had been used. (If we find we need the parameter again in the future it's easy enough to add back again.) Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: snapc is unused in rbd_req_sync_read()Alex Elder2012-07-30
| | | | | | | | | The "snapc" parameter to in rbd_req_sync_read() is not used, so get rid of it. Reported-by: Josh Durgin <josh.durgin@inktank.com> Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: rename rbd_device->idAlex Elder2012-07-30
| | | | | | | | | | | | | | | The "id" field of an rbd device structure represents the unique client-local device id mapped to the underlying rbd image. Each rbd image will have another id--the image id--and each snapshot has its own id as well. The simple name "id" no longer conveys the information one might like to have. Rename the device "id" field in struct rbd_dev to be "dev_id" to make it a little more obvious what we're dealing with without having to think more about context. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: encapsulate header validity testAlex Elder2012-07-30
| | | | | | | | | | | | | If an rbd image header is read and it doesn't begin with the expected magic information, a warning is displayed. This is a fairly simple test, but it could be extended at some point. Fix the comparison so it actually looks at the "text" field rather than the front of the structure. In any case, encapsulate the validity test in its own function. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: clean up a few dout() callsAlex Elder2012-07-30
| | | | | | | | | | There was a dout() call in rbd_do_request() that was reporting the reporting the offset as the length and vice versa. While fixing that I did a quick scan of other dout() calls and fixed a couple of other minor things. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: simplify __rbd_remove_all_snaps()Alex Elder2012-07-30
| | | | | | | | This just replaces a while loop with list_for_each_entry_safe() in __rbd_remove_all_snaps(). Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: drop extra header_rwsem initAlex Elder2012-07-30
| | | | | | | | | | In commit c666601a there was inadvertently added an extra initialization of rbd_dev->header_rwsem. This gets rid of the duplicate. Reported-by: Guangliang Zhao <gzhao@suse.com> Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: kill rbd_image_header->snap_seqAlex Elder2012-07-30
| | | | | | | | | | The snap_seq field in an rbd_image_header structure held the value from the rbd image header when it was last refreshed. We now maintain this value in the snapc->seq field. So get rid of the other one. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: set snapc->seq only when refreshing headerAlex Elder2012-07-30
| | | | | | | | | | | | | | | | | | In rbd_header_add_snap() there is code to set snapc->seq to the just-added snapshot id. This is the only remnant left of the use of that field for recording which snapshot an rbd_dev was associated with. That functionality is no longer supported, so get rid of that final bit of code. Doing so means we never actually set snapc->seq any more. On the server, the snapshot context's sequence value represents the highest snapshot id ever issued for a particular rbd image. So we'll make it have that meaning here as well. To do so, set this value whenever the rbd header is (re-)read. That way it will always be consistent with the rest of the snapshot context we maintain. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: preserve snapc->seq in rbd_header_set_snap()Alex Elder2012-07-30
| | | | | | | | | | | | | | | | | In rbd_header_set_snap(), there is logic to make the snap context's seq field get set to a particular snapshot id, or 0 if there is no snapshot for the rbd image. This seems to be an artifact of how the current snapshot id for an rbd_dev was recorded before the rbd_dev->snap_id field began to be used for that purpose. There's no need to update the value of snapc->seq here any more, so stop doing it. Tidy up a few local variables in that function while we're at it. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: don't use snapc->seq that wayAlex Elder2012-07-30
| | | | | | | | | | | | | | | | | | | In what appears to be an artifact of a different way of encoding whether an rbd image maps a snapshot, __rbd_refresh_header() has code that arranges to update the seq value in an rbd image's snapshot context to point to the first entry in its snapshot array if that's where it was pointing initially. We now use rbd_dev->snap_id to record the snapshot id--using the special value CEPH_NOSNAP to indicate the rbd_dev is not mapping a snapshot at all. There is therefore no need to check for this case, nor to update the seq value, in __rbd_refresh_header(). Just preserve the seq value that rbd_read_header() provides (which, at the moment, is nothing). Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
* rbd: send header version when notifyingJosh Durgin2012-07-30
| | | | | | | | Previously the original header version was sent. Now, we update it when the header changes. Signed-off-by: Josh Durgin <josh.durgin@dreamhost.com> Reviewed-by: Alex Elder <elder@inktank.com>
* rbd: use reference counting for the snap contextJosh Durgin2012-07-30
| | | | | | | | | | | | | | This prevents a race between requests with a given snap context and header updates that free it. The osd client was already expecting the snap context to be reference counted, since it get()s it in ceph_osdc_build_request and put()s it when the request completes. Also remove the second down_read()/up_read() on header_rwsem in rbd_do_request, which wasn't actually preventing this race or protecting any other data. Signed-off-by: Josh Durgin <josh.durgin@dreamhost.com> Reviewed-by: Alex Elder <elder@inktank.com>