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2012-10-24libceph: avoid NULL kref_put when osd reset races with alloc_msgSage Weil
The ceph_on_in_msg_alloc() method drops con->mutex while it allocates a message. If that races with a timeout that resends a zillion messages and resets the connection, and the ->alloc_msg() method returns a NULL message, it will call ceph_msg_put(NULL) and BUG. Fix by only calling put if msg is non-NULL. Fixes http://tracker.newdream.net/issues/3142 Signed-off-by: Sage Weil <sage@inktank.com>
2012-10-10rbd: reset BACKOFF if unable to re-queueAlex Elder
If ceph_fault() is unable to queue work after a delay, it sets the BACKOFF connection flag so con_work() will attempt to do so. In con_work(), when BACKOFF is set, if queue_delayed_work() doesn't result in newly-queued work, it simply ignores this condition and proceeds as if no backoff delay were desired. There are two problems with this--one of which is a bug. The first problem is simply that the intended behavior is to back off, and if we aren't able queue the work item to run after a delay we're not doing that. The only reason queue_delayed_work() won't queue work is if the provided work item is already queued. In the messenger, this means that con_work() is already scheduled to be run again. So if we simply set the BACKOFF flag again when this occurs, we know the next con_work() call will again attempt to hold off activity on the connection until after the delay. The second problem--the bug--is a leak of a reference count. If queue_delayed_work() returns 0 in con_work(), con->ops->put() drops the connection reference held on entry to con_work(). However, processing is (was) allowed to continue, and at the end of the function a second con->ops->put() is called. This patch fixes both problems. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Sage Weil <sage@inktank.com>
2012-10-03ceph: avoid 32-bit page index overflowAlex Elder
A pgoff_t is defined (by default) to have type (unsigned long). On architectures such as i686 that's a 32-bit type. The ceph address space code was attempting to produce 64 bit offsets by shifting a page's index by PAGE_CACHE_SHIFT, but the result was not what was desired because the shift occurred before the result got promoted to 64 bits. Fix this by converting all uses of page->index used in this way to use the page_offset() macro, which ensures the 64-bit result has the intended value. This fixes http://tracker.newdream.net/issues/3112 Reported-by: Mohamed Pakkeer <pakkeer.mohideen@realimage.com> Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Sage Weil <sage@inktank.com>
2012-10-03ceph: return EIO on invalid layout on GET_DATALOC ioctlSage Weil
If the user calls GET_DATALOC on a file with an invalid (e.g., zeroed) layout, return EIO to userland. Signed-off-by: Sage Weil <sage@inktank.com> Reviewed-by: Alex Elder <elder@inktank.com>
2012-10-01rbd: BUG on invalid layoutSage Weil
This shouldn't actually be possible because the layout struct is constructed from the RBD header and validated then. [elder@inktank.com: converted BUG() call to equivalent rbd_assert()] Signed-off-by: Sage Weil <sage@inktank.com> Reviewed-by: Alex Elder <elder@inktank.com>
2012-10-01ceph: propagate layout error on osd request creationSage Weil
If we are creating an osd request and get an invalid layout, return an EINVAL to the caller. We switch up the return to have an error code instead of NULL implying -ENOMEM. Signed-off-by: Sage Weil <sage@inktank.com> Reviewed-by: Alex Elder <elder@inktank.com>
2012-10-01libceph: check for invalid mappingSage Weil
If we encounter an invalid (e.g., zeroed) mapping, return an error and avoid a divide by zero. Signed-off-by: Sage Weil <sage@inktank.com> Reviewed-by: Alex Elder <elder@inktank.com>
2012-10-01ceph: convert to use le32_add_cpu()Wei Yongjun
Convert cpu_to_le32(le32_to_cpu(E1) + E2) to use le32_add_cpu(). dpatch engine is used to auto generate this patch. (https://github.com/weiyj/dpatch) Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Sage Weil <sage@inktank.com>
2012-10-01ceph: Fix oops when handling mdsmap that decreases max_mdsYan, Zheng
When i >= newmap->m_max_mds, ceph_mdsmap_get_addr(newmap, i) return NULL. Passing NULL to memcmp() triggers oops. Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com> Signed-off-by: Sage Weil <sage@inktank.com>
2012-10-01rbd: update remaining header fields for v2Alex Elder
There are three fields that are not yet updated for format 2 rbd image headers: the version of the header object; the encryption type; and the compression type. There is no interface defined for fetching the latter two, so just initialize them explicitly to 0 for now. Change rbd_dev_v2_snap_context() so the caller can be supplied the version for the header object. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: get snapshot name for a v2 imageAlex Elder
Define rbd_dev_v2_snap_name() to fetch the name for a particular snapshot in a format 2 rbd image. Define rbd_dev_v2_snap_info() to to be a wrapper for getting the name, size, and features for a particular snapshot, using an interface that matches the equivalent function for version 1 images. Define rbd_dev_snap_info() wrapper function and use it to call the appropriate function for getting the snapshot name, size, and features, dependent on the rbd image format. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: get the snapshot context for a v2 imageAlex Elder
Fetch the snapshot context for an rbd format 2 image by calling the "get_snapcontext" method on its header object. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: get image features for a v2 imageAlex Elder
The features values for an rbd format 2 image are fetched from the server using a "get_features" method. The same method is used for getting the features for a snapshot, so structure this addition with a generic helper routine that can get this information for either. The server will provide two 64-bit feature masks, one representing the features potentially in use for this image (or its snapshot), and one representing features that must be supported by the client in order to work with the image. For the time being, neither of these is really used so we keep things simple and just record the first feature vector. Once we start using these feature masks, what we record and what we expose to the user will most likely change. Signed-off-by: Alex Elder <elder@inktank.com>
2012-10-01rbd: get the object prefix for a v2 rbd imageAlex Elder
The object prefix of an rbd format 2 image is fetched from the server using a "get_object_prefix" method. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: add code to get the size of a v2 rbd imageAlex Elder
The size of an rbd format 2 image is fetched from the server using a "get_size" method. The same method is used for getting the size of a snapshot, so structure this addition with a generic helper routine that we can get this information for either. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: lay out header probe infrastructureAlex Elder
This defines a new function rbd_dev_probe() as a top-level function for populating detailed information about an rbd device. It first checks for the existence of a format 2 rbd image id object. If it exists, the image is assumed to be a format 2 rbd image, and another function rbd_dev_v2() is called to finish populating header data for that image. If it does not exist, it is assumed to be an old (format 1) rbd image, and calls a similar function rbd_dev_v1() to populate its header information. A new field, rbd_dev->format, is defined to record which version of the rbd image format the device represents. For a valid mapped rbd device it will have one of two values, 1 or 2. So far, the format 2 images are not really supported; this is laying out the infrastructure for fleshing out that support. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: encapsulate code that gets snapshot infoAlex Elder
Create a function that encapsulates looking up the name, size and features related to a given snapshot, which is indicated by its index in an rbd device's snapshot context array of snapshot ids. This interface will be used to hide differences between the format 1 and format 2 images. At the moment this (looking up the name anyway) is slightly less efficient than what's done currently, but we may be able to optimize this a bit later on by cacheing the last lookup if it proves to be a problem. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: add an rbd features fieldAlex Elder
Record the features values for each rbd image and each of its snapshots. This is really something that only becomes meaningful for version 2 images, so this is just putting in place code that will form common infrastructure. It may be useful to expand the sysfs entries--and therefore the information we maintain--for the image and for each snapshot. But I'm going to hold off doing that until we start making active use of the feature bits. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: don't use index in __rbd_add_snap_dev()Alex Elder
Pass the snapshot id and snapshot size rather than an index to __rbd_add_snap_dev() to specify values for a new snapshot. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-01rbd: kill create_snap sysfs entryAlex Elder
Josh proposed the following change, and I don't think I could explain it any better than he did: From: Josh Durgin <josh.durgin@inktank.com> Date: Tue, 24 Jul 2012 14:22:11 -0700 To: ceph-devel <ceph-devel@vger.kernel.org> Message-ID: <500F1203.9050605@inktank.com> Right now the kernel still has one piece of rbd management duplicated from the rbd command line tool: snapshot creation. There's nothing special about snapshot creation that makes it advantageous to do from the kernel, so I'd like to remove the create_snap sysfs interface. That is, /sys/bus/rbd/devices/<id>/create_snap would be removed. Does anyone rely on the sysfs interface for creating rbd snapshots? If so, how hard would it be to replace with: rbd snap create pool/image@snap Is there any benefit to the sysfs interface that I'm missing? Josh This patch implements this proposal, removing the code that implements the "snap_create" sysfs interface for rbd images. As a result, quite a lot of other supporting code goes away. Suggested-by: Josh Durgin <josh.durgin@inktank.com> Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
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>