Commit Graph

323310 Commits

Author SHA1 Message Date
Alex Elder
3ee4001e0c rbd: set up watch before announcing disk
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>
2012-10-01 14:30:52 -05:00
Alex Elder
12f029448c rbd: set initial capacity in rbd_init_disk()
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>
2012-10-01 14:30:52 -05:00
Alex Elder
86ff77bb68 rbd: drop dev registration check for new snap
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>
2012-10-01 14:30:52 -05:00
Alex Elder
0f308a3188 rbd: call rbd_init_disk() sooner
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>
2012-10-01 14:30:52 -05:00
Alex Elder
85ae892675 rbd: defer setting device id
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>
2012-10-01 14:30:52 -05:00
Alex Elder
05fd6f6f8c rbd: read the header before registering device
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>
2012-10-01 14:30:52 -05:00
Alex Elder
5ed1617731 rbd: call set_snap() before snap_devs_update()
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>
2012-10-01 14:30:52 -05:00
Alex Elder
304f68086f rbd: defer registering snapshot devices
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>
2012-10-01 14:30:52 -05:00
Alex Elder
3fcf2581c2 rbd: assign header name later
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>
2012-10-01 14:30:52 -05:00
Alex Elder
e86924a809 rbd: use snaps list in rbd_snap_by_name()
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>
2012-10-01 14:30:52 -05:00
Alex Elder
cd789ab9ca rbd: don't register snapshots in bus_add_dev()
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>
2012-10-01 14:30:52 -05:00
Alex Elder
4bb1f1ed00 rbd: move locking out of rbd_header_set_snap()
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>
2012-10-01 14:30:51 -05:00
Alex Elder
1fcdb8aa1f rbd: simplify rbd_init_disk() a bit
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>
2012-10-01 14:30:51 -05:00
Alex Elder
2ac4e75d89 rbd: do some header initialization earlier
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>
2012-10-01 14:30:51 -05:00
Alex Elder
8836b995fd rbd: simplify snap_by_name() interface
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>
2012-10-01 14:30:51 -05:00
Alex Elder
4e1105a299 rbd: set mapping name with the rest
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>
2012-10-01 14:30:51 -05:00
Alex Elder
3feeb89467 rbd: return snap name from rbd_add_parse_args()
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>
2012-10-01 14:30:51 -05:00
Alex Elder
99c1f08f64 rbd: record mapped size
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>
2012-10-01 14:30:51 -05:00
Alex Elder
f84344f334 rbd: separate mapping info in rbd_dev
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>
2012-10-01 14:30:51 -05:00
Alex Elder
c9aadfe786 rbd: kill rbd_image_header->total_snaps
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>
2012-10-01 14:30:51 -05:00
Alex Elder
98cec111c0 rbd: kill rbd_dev->q
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>
2012-10-01 14:30:51 -05:00
Alex Elder
9fcbb80024 rbd: rename __rbd_init_snaps_header()
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>
2012-10-01 14:30:50 -05:00
Alex Elder
e28393082d rbd: rename rbd_id_get()
This should have been done as part of this commit:

    commit de71a2970d
    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>
2012-10-01 14:30:50 -05:00
Alex Elder
aafb230ebc rbd: define rbd_assert()
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>
2012-10-01 14:30:50 -05:00
Alex Elder
65ccfe21dd rbd: split up rbd_get_segment()
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>
2012-10-01 14:30:50 -05:00
Alex Elder
df111be631 rbd: check for overflow in rbd_get_num_segments()
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>
2012-10-01 14:30:50 -05:00
Alex Elder
38f5f65e9d rbd: drop needless test in rbd_rq_fn()
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>
2012-10-01 14:30:50 -05:00
Alex Elder
542582fce1 rbd: bio_chain_clone() cleanups
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>
2012-10-01 14:30:50 -05:00
Alex Elder
84d34dcc11 rbd: kill notify_timeout option
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>
2012-10-01 14:30:50 -05:00
Alex Elder
cc0538b62c rbd: add read_only rbd map option
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>
2012-10-01 14:30:50 -05:00
Alex Elder
f8c3892911 rbd: move rbd_opts to struct rbd_device
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>
2012-10-01 14:30:50 -05:00
Alex Elder
621901d652 rbd: more cleanup in rbd_header_from_disk()
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>
2012-10-01 14:30:50 -05:00
Alex Elder
f785cc1dbe rbd: kill incore snap_names_len
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>
2012-10-01 14:30:49 -05:00
Alex Elder
58c17b0e1b rbd: don't over-allocate space for object prefix
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>
2012-10-01 14:30:49 -05:00
Alex Elder
1f7ba33115 rbd: handle locking inside __rbd_client_find()
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>
2012-10-01 14:30:49 -05:00
Wei Yongjun
cc4829e596 ceph: use list_move_tail instead of list_del/list_add_tail
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>
2012-10-01 14:30:49 -05:00
Alex Elder
523f32582f rbd: add new snapshots at the tail
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>
2012-10-01 14:30:49 -05:00
Alex Elder
843a0d0879 rbd: rename block_name -> object_prefix
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>
2012-10-01 14:30:49 -05:00
Iulius Curt
7698f2f5e0 libceph: Fix sparse warning
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>
2012-10-01 14:30:49 -05:00
Sage Weil
290e33593d libceph: remove unused monc->have_fsid
This is unused; use monc->client->have_fsid.

Signed-off-by: Sage Weil <sage@inktank.com>
2012-10-01 14:30:49 -05:00
Alex Elder
c98f533c94 ceph: let path portion of mount "device" be optional
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>
2012-10-01 14:30:49 -05:00
Alex Elder
4156d99840 rbd: separate reading header from decoding it
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>
2012-10-01 14:30:49 -05:00
Alex Elder
103a150f0c rbd: expand rbd_dev_ondisk_valid() checks
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>
2012-10-01 14:30:48 -05:00
Alex Elder
28cb775de1 rbd: return earlier in rbd_header_from_disk()
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>
2012-10-01 14:30:48 -05:00
Alex Elder
6a52325f61 rbd: rearrange rbd_header_from_disk()
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>
2012-10-01 14:30:48 -05:00
Alex Elder
d2bb24e506 rbd: use sizeof (object) instead of sizeof (type)
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>
2012-10-01 14:30:48 -05:00
Alex Elder
d78fd7ae03 rbd: ensure invalid pointers are made null
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>
2012-10-01 14:30:48 -05:00
Alex Elder
0f1d3f9385 rbd: make snap_names_len a u64
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>
2012-10-01 14:30:48 -05:00
Alex Elder
3593815022 rbd: simplify __rbd_init_snaps_header()
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>
2012-10-01 14:30:48 -05:00
Linus Torvalds
a0d271cbfe Linux 3.6 2012-09-30 16:47:46 -07:00