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2012-10-01rbd: define rbd_dev_image_id()Alex Elder
New format 2 rbd images are permanently identified by a unique image id. Each rbd image also has a name, but the name can be changed. A format 2 rbd image will have an object--whose name is based on the image name--which maps an image's name to its image id. Create a new function rbd_dev_image_id() that checks for the existence of the image id object, and if it's found, records the image id in the rbd_device structure. Create a new rbd device attribute (/sys/bus/rbd/<num>/image_id) that makes this information available. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: define some new format constantsAlex Elder
Define constant symbols related to the rbd format 2 object names. This begins to bring this version of the "rbd_types.h" header more in line with the current user-space version of that file. Complete reconciliation of differences will be done at some point later, as a separate task. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: support data returned from OSD methodsAlex Elder
An OSD object method call can be made using rbd_req_sync_exec(). Until now this has only been used for creating a new RBD snapshot, and that has only required sending data out, not receiving anything back from the OSD. We will now need to get data back from an OSD on a method call, so add parameters to rbd_req_sync_exec() that allow a buffer into which returned data should be placed to be specified, along with its size. Previously, rbd_req_sync_exec() passed a null pointer and zero size to rbd_req_sync_op(); change this so the new inbound buffer information is provided instead. Rename the "buf" and "len" parameters in rbd_req_sync_op() to make it more obvious they are describing inbound data. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: pass flags to rbd_req_sync_exec()Alex Elder
In order to allow both read requests and write requests to be initiated using rbd_req_sync_exec(), add an OSD flags value which can be passed down to rbd_req_sync_op(). Rename the "data" and "len" parameters to be more clear that they represent data that is outbound. At this point, this function is still only used (and only works) for write requests. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: set up watch before announcing diskAlex Elder
We're ready to handle header object (refresh) events at the point we call rbd_bus_add_dev(). Set up the watch request on the rbd image header just after that, and after we've registered the devices for the snapshots for the initial snapshot context. Do this before announce the disk as available for use. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: set initial capacity in rbd_init_disk()Alex Elder
Move the setting of the initial capacity for an rbd image mapping into rb_init_disk(). Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: drop dev registration check for new snapAlex Elder
By the time rbd_dev_snaps_register() gets called during rbd device initialization, the main device will have already been registered. Similarly, a header refresh will only occur for an rbd device whose Linux device is registered. There is therefore no need to verify the main device is registered when registering a snapshot device. For the time being, turn the check into a WARN_ON(), but it can eventually just go away. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: call rbd_init_disk() soonerAlex Elder
Call rbd_init_disk() from rbd_add() as soon as we have the major device number for the mapping. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: defer setting device idAlex Elder
Hold off setting the device id and formatting the device name in rbd_add() until just before it's needed. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: read the header before registering deviceAlex Elder
Read the rbd header information and call rbd_dev_set_mapping() earlier--before registering the block device or setting up the sysfs entries for the image. The sysfs entries provide users access to some information that's only available after doing the rbd header initialization, so this will make sure it's valid right away. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: call set_snap() before snap_devs_update()Alex Elder
rbd_header_set_snap() is a simple initialization routine for an rbd device's mapping. It has to be called after the snapshot context for the rbd_dev has been updated, but can be done before snapshot devices have been registered. Change the name to rbd_dev_set_mapping() to better reflect its purpose, and call it a little sooner, before registering snapshot devices. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: defer registering snapshot devicesAlex Elder
When a new snapshot is found in an rbd device's updated snapshot context, __rbd_add_snap_dev() is called to create and insert an entry in the rbd devices list of snapshots. In addition, a Linux device is registered to represent the snapshot. For version 2 rbd images, it will be undesirable to initialize the device right away. So in anticipation of that, this patch separates the insertion of a snapshot entry in the snaps list from the creation of devices for those snapshots. To do this, create a new function rbd_dev_snaps_register() which traverses the list of snapshots and calls rbd_register_snap_dev() on any that have not yet been registered. Rename rbd_dev_snap_devs_update() to be rbd_dev_snaps_update() to better reflect that only the entry in the snaps list and not the snapshot's device is affected by the function. For now, call rbd_dev_snaps_register() immediately after each call to rbd_dev_snaps_update(). Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: assign header name laterAlex Elder
Move the assignment of the header name for an rbd image a bit later, outside rbd_add_parse_args() and into its caller. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: use snaps list in rbd_snap_by_name()Alex Elder
An rbd_dev structure maintains a list of current snapshots that have already been fully initialized. The entries on the list have type struct rbd_snap, and each entry contains a copy of information that's found in the rbd_dev's snapshot context and header. The only caller of snap_by_name() is rbd_header_set_snap(). In that call site any positive return value (the index in the snapshot array) is ignored, so there's no need to return the index in the snapshot context's id array when it's found. rbd_header_set_snap() also has only one caller--rbd_add()--and that call is made after a call to rbd_dev_snap_devs_update(). Because the rbd_snap structures are initialized in that function, the current snapshot list can be used instead of the snapshot context to look up a snapshot's information by name. Change snap_by_name() so it uses the snapshot list rather than the rbd_dev's snapshot context in looking up snapshot information. Return 0 if it's found rather than the snapshot id. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: don't register snapshots in bus_add_dev()Alex Elder
When rbd_bus_add_dev() is called (one spot--in rbd_add()), the rbd image header has not even been read yet. This means that the list of snapshots will be empty at the time of the call. As a result, there is no need for the code that calls rbd_register_snap_dev() for each entry in that list--so get rid of it. Once the header has been read (just after returning), a call will be made to rbd_dev_snap_devs_update(), which will then find every snapshot in the context to be new and will therefore call rbd_register_snap_dev() via __rbd_add_snap_dev() accomplishing the same thing. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: move locking out of rbd_header_set_snap()Alex Elder
Move the calls to get the header semaphore out of rbd_header_set_snap() and into its caller. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: simplify rbd_init_disk() a bitAlex Elder
This just simplifies a few things in rbd_init_disk(), now that the previous patch has moved a bunch of initialization code out if it. Done separately to facilitate review. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: do some header initialization earlierAlex Elder
Move some of the code that initializes an rbd header out of rbd_init_disk() and into its caller. Move the code at the end of rbd_init_disk() that sets the device capacity and activates the Linux device out of that function and into the caller, ensuring we still have the disk size available where we need it. Update rbd_free_disk() so it still aligns well as an inverse of rbd_init_disk(), moving the rbd_header_free() call out to its caller. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: simplify snap_by_name() interfaceAlex Elder
There is only one caller of snap_by_name(), and it passes two values to be assigned, both of which are found within an rbd device structure. Change the interface so it just passes the address of the rbd_dev, and make the assignments to its fields directly. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: set mapping name with the restAlex Elder
With the exception of the snapshot name, all of the mapping-specific fields in an rbd device structure are set in rbd_header_set_snap(). Pass the snapshot name to be assigned into rbd_header_set_snap() to keep all of the mapping assignments together. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: return snap name from rbd_add_parse_args()Alex Elder
This is the first of two patches aimed at isolating the code that sets the mapping information into a single spot. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: record mapped sizeAlex Elder
Add the size of the mapped image to the set of mapping-specific fields in an rbd_device, and use it when setting the capacity of the disk. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: separate mapping info in rbd_devAlex Elder
Several fields in a struct rbd_dev are related to what is mapped, as opposed to the actual base rbd image. If the base image is mapped these are almost unneeded, but if a snapshot is mapped they describe information about that snapshot. In some contexts this can be a little bit confusing. So group these mapping-related field into a structure to make it clear what they are describing. This also includes a minor change that rearranges the fields in the in-core image header structure so that invariant fields are at the top, followed by those that change. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: kill rbd_image_header->total_snapsAlex Elder
The "total_snaps" field in an rbd header structure is never any different from the value of "num_snaps" stored within a snapshot context. Avoid any confusion by just using the value held within the snapshot context, and get rid of the "total_snaps" field. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: kill rbd_dev->qAlex Elder
A copy of rbd_dev->disk->queue is held in rbd_dev->q, but it's never actually used. So get just get rid of the field. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: rename __rbd_init_snaps_header()Alex Elder
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>
2012-10-01rbd: rename rbd_id_get()Alex Elder
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>
2012-10-01rbd: define rbd_assert()Alex Elder
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>
2012-10-01rbd: split up rbd_get_segment()Alex Elder
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>
2012-10-01rbd: check for overflow in rbd_get_num_segments()Alex Elder
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>
2012-10-01rbd: drop needless test in rbd_rq_fn()Alex Elder
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>
2012-10-01rbd: bio_chain_clone() cleanupsAlex Elder
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>
2012-10-01rbd: kill notify_timeout optionAlex Elder
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>
2012-10-01rbd: add read_only rbd map optionAlex Elder
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>
2012-10-01rbd: move rbd_opts to struct rbd_deviceAlex Elder
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>
2012-10-01rbd: more cleanup in rbd_header_from_disk()Alex Elder
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>
2012-10-01rbd: kill incore snap_names_lenAlex Elder
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>
2012-10-01rbd: don't over-allocate space for object prefixAlex Elder
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>
2012-10-01rbd: handle locking inside __rbd_client_find()Alex Elder
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>
2012-10-01ceph: use list_move_tail instead of list_del/list_add_tailWei Yongjun
Using list_move_tail() instead of list_del() + list_add_tail(). Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Sage Weil <sage@inktank.com>
2012-10-01rbd: add new snapshots at the tailAlex Elder
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>
2012-10-01rbd: rename block_name -> object_prefixAlex Elder
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>
2012-10-01libceph: Fix sparse warningIulius Curt
Make ceph_monc_do_poolop() static to remove the following sparse warning: * net/ceph/mon_client.c:616:5: warning: symbol 'ceph_monc_do_poolop' was not declared. Should it be static? Also drops the 'ceph_monc_' prefix, now being a private function. Signed-off-by: Iulius Curt <icurt@ixiacom.com> Signed-off-by: Sage Weil <sage@inktank.com>
2012-10-01libceph: remove unused monc->have_fsidSage Weil
This is unused; use monc->client->have_fsid. Signed-off-by: Sage Weil <sage@inktank.com>
2012-10-01ceph: let path portion of mount "device" be optionalAlex Elder
A recent change to /sbin/mountall causes any trailing '/' character in the "device" (or fs_spec) field in /etc/fstab to be stripped. As a result, an entry for a ceph mount that intends to mount the root of the name space ends up with now path portion, and the ceph mount option processing code rejects this. That is, an entry in /etc/fstab like: cephserver:port:/ /mnt ceph defaults 0 0 provides to the ceph code just "cephserver:port:" as the "device," and that gets rejected. Although this is a bug in /sbin/mountall, we can have the ceph mount code support an empty/nonexistent path, interpreting it to mean the root of the name space. RFC 5952 offers recommendations for how to express IPv6 addresses, and recommends the usage found in RFC 3986 (which specifies the format for URI's) for representing both IPv4 and IPv6 addresses that include port numbers. (See in particular the definition of "authority" found in the Appendix of RFC 3986.) According to those standards, no host specification will ever contain a '/' character. As a result, it is sufficient to scan a provided "device" from an /etc/fstab entry for the first '/' character, and if it's found, treat that as the beginning of the path. If no '/' character is present, we can treat the entire string as the monitor host specification(s), and assume the path to be the root of the name space. We'll still require a ':' to separate the host portion from the (possibly empty) path portion. This means that we can more formally define how ceph will interpret the "device" it's provided when processing a mount request: "device" will look like: <server_spec>[,<server_spec>...]:[<path>] where <server_spec> is <ip>[:<port>] <path> is optional, but if present must begin with '/' This addresses http://tracker.newdream.net/issues/2919 Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Dan Mick <dan.mick@inktank.com>
2012-10-01rbd: separate reading header from decoding itAlex Elder
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>
2012-10-01rbd: expand rbd_dev_ondisk_valid() checksAlex Elder
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>
2012-10-01rbd: return earlier in rbd_header_from_disk()Alex Elder
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>
2012-10-01rbd: rearrange rbd_header_from_disk()Alex Elder
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>
2012-10-01rbd: use sizeof (object) instead of sizeof (type)Alex Elder
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>