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Lukas Czerner 569d39fc3e ceph: use ->invalidatepage() length argument
->invalidatepage() aop now accepts range to invalidate so we can make
use of it in ceph_invalidatepage().

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Acked-by: Sage Weil <sage@inktank.com>
Cc: ceph-devel@vger.kernel.org
2013-05-21 23:58:48 -04:00
Lukas Czerner d47992f86b mm: change invalidatepage prototype to accept length
Currently there is no way to truncate partial page where the end
truncate point is not at the end of the page. This is because it was not
needed and the functionality was enough for file system truncate
operation to work properly. However more file systems now support punch
hole feature and it can benefit from mm supporting truncating page just
up to the certain point.

Specifically, with this functionality truncate_inode_pages_range() can
be changed so it supports truncating partial page at the end of the
range (currently it will BUG_ON() if 'end' is not at the end of the
page).

This commit changes the invalidatepage() address space operation
prototype to accept range to be invalidated and update all the instances
for it.

We also change the block_invalidatepage() in the same way and actually
make a use of the new length argument implementing range invalidation.

Actual file system implementations will follow except the file systems
where the changes are really simple and should not change the behaviour
in any way .Implementation for truncate_page_range() which will be able
to accept page unaligned ranges will follow as well.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
2013-05-21 23:17:23 -04:00
Alex Elder 406e2c9f92 libceph: kill off osd data write_request parameters
In the incremental move toward supporting distinct data items in an
osd request some of the functions had "write_request" parameters to
indicate, basically, whether the data belonged to in_data or the
out_data.  Now that we maintain the data fields in the op structure
there is no need to indicate the direction, so get rid of the
"write_request" parameters.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:18:58 -07:00
Yan, Zheng 1ac0fc8adf ceph: fix race between writepages and truncate
ceph_writepages_start() reads inode->i_size in two places. It can get
different values between successive read, because truncate can change
inode->i_size at any time. The race can lead to mismatch between data
length of osd request and pages marked as writeback. When osd request
finishes, it clear writeback page according to its data length. So
some pages can be left in writeback state forever. The fix is only
read inode->i_size once, save its value to a local variable and use
the local variable when i_size is needed.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Alex Elder <elder@inktank.com>
2013-05-01 21:18:55 -07:00
Alex Elder a4ce40a9a7 libceph: combine initializing and setting osd data
This ends up being a rather large patch but what it's doing is
somewhat straightforward.

Basically, this is replacing two calls with one.  The first of the
two calls is initializing a struct ceph_osd_data with data (either a
page array, a page list, or a bio list); the second is setting an
osd request op so it associates that data with one of the op's
parameters.  In place of those two will be a single function that
initializes the op directly.

That means we sort of fan out a set of the needed functions:
    - extent ops with pages data
    - extent ops with pagelist data
    - extent ops with bio list data
and
    - class ops with page data for receiving a response

We also have define another one, but it's only used internally:
    - class ops with pagelist data for request parameters

Note that we *still* haven't gotten rid of the osd request's
r_data_in and r_data_out fields.  All the osd ops refer to them for
their data.  For now, these data fields are pointers assigned to the
appropriate r_data_* field when these new functions are called.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:18:23 -07:00
Alex Elder c99d2d4abb libceph: specify osd op by index in request
An osd request now holds all of its source op structures, and every
place that initializes one of these is in fact initializing one
of the entries in the the osd request's array.

So rather than supplying the address of the op to initialize, have
caller specify the osd request and an indication of which op it
would like to initialize.  This better hides the details the
op structure (and faciltates moving the data pointers they use).

Since osd_req_op_init() is a common routine, and it's not used
outside the osd client code, give it static scope.  Also make
it return the address of the specified op (so all the other
init routines don't have to repeat that code).

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:18:15 -07:00
Alex Elder 8c042b0df9 libceph: add data pointers in osd op structures
An extent type osd operation currently implies that there will
be corresponding data supplied in the data portion of the request
(for write) or response (for read) message.  Similarly, an osd class
method operation implies a data item will be supplied to receive
the response data from the operation.

Add a ceph_osd_data pointer to each of those structures, and assign
it to point to eithre the incoming or the outgoing data structure in
the osd message.  The data is not always available when an op is
initially set up, so add two new functions to allow setting them
after the op has been initialized.

Begin to make use of the data item pointer available in the osd
operation rather than the request data in or out structure in
places where it's convenient.  Add some assertions to verify
pointers are always set the way they're expected to be.

This is a sort of stepping stone toward really moving the data
into the osd request ops, to allow for some validation before
making that jump.

This is the first in a series of patches that resolve:
    http://tracker.ceph.com/issues/4657

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:18:14 -07:00
Alex Elder 79528734f3 libceph: keep source rather than message osd op array
An osd request keeps a pointer to the osd operations (ops) array
that it builds in its request message.

In order to allow each op in the array to have its own distinct
data, we will need to keep track of each op's data, and that
information does not go over the wire.

As long as we're tracking the data we might as well just track the
entire (source) op definition for each of the ops.  And if we're
doing that, we'll have no more need to keep a pointer to the
wire-encoded version.

This patch makes the array of source ops be kept with the osd
request structure, and uses that instead of the version encoded in
the message in places where that was previously used.  The array
will be embedded in the request structure, and the maximum number of
ops we ever actually use is currently 2.  So reduce CEPH_OSD_MAX_OP
to 2 to reduce the size of the structure.

The result of doing this sort of ripples back up, and as a result
various function parameters and local variables become unnecessary.

Make r_num_ops be unsigned, and move the definition of struct
ceph_osd_req_op earlier to ensure it's defined where needed.

It does not yet add per-op data, that's coming soon.

This resolves:
    http://tracker.ceph.com/issues/4656

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:18:12 -07:00
Alex Elder 87060c1089 libceph: a few more osd data cleanups
These are very small changes that make use osd_data local pointers
as shorthands for structures being operated on.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:18:10 -07:00
Alex Elder 43bfe5de9f libceph: define osd data initialization helpers
Define and use functions that encapsulate the initializion of a
ceph_osd_data structure.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:18:06 -07:00
Alex Elder e5975c7c8e ceph: build osd request message later for writepages
Hold off building the osd request message in ceph_writepages_start()
until just before it will be submitted to the osd client for
execution.

We'll still create the request and allocate the page pointer array
after we learn we have at least one page to write.  A local variable
will be used to keep track of the allocated array of pages.  Wait
until just before submitting the request for assigning that page
array pointer to the request message.

Create ands use a new function osd_req_op_extent_update() whose
purpose is to serve this one spot where the length value supplied
when an osd request's op was initially formatted might need to get
changed (reduced, never increased) before submitting the request.

Previously, ceph_writepages_start() assigned the message header's
data length because of this update.  That's no longer necessary,
because ceph_osdc_build_request() will recalculate the right
value to use based on the content of the ops in the request.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:18:02 -07:00
Alex Elder 02ee07d300 libceph: hold off building osd request
Defer building the osd request until just before submitting it in
all callers except ceph_writepages_start().  (That caller will be
handed in the next patch.)

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:18:01 -07:00
Alex Elder 88486957f9 ceph: kill ceph alloc_page_vec()
There is a helper function alloc_page_vec() that, despite its
generic sounding name depends heavily on an osd request structure
being populated with certain information.

There is only one place this function is used, and it ends up
being a bit simpler to just open code what it does, so get
rid of the helper.

The real motivation for this is deferring building the of the osd
request message, and this is a step in that direction.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:18:00 -07:00
Alex Elder 94fe8420bf ceph: define ceph_writepages_osd_request()
Mostly for readability, define ceph_writepages_osd_request() and
use it to allocate the osd request for ceph_writepages_start().

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:17:59 -07:00
Alex Elder acead002b2 libceph: don't build request in ceph_osdc_new_request()
This patch moves the call to ceph_osdc_build_request() out of
ceph_osdc_new_request() and into its caller.

This is in order to defer formatting osd operation information into
the request message until just before request is started.

The only unusual (ab)user of ceph_osdc_build_request() is
ceph_writepages_start(), where the final length of write request may
change (downward) based on the current inode size or the oldest
snapshot context with dirty data for the inode.

The remaining callers don't change anything in the request after has
been built.

This means the ops array is now supplied by the caller.  It also
means there is no need to pass the mtime to ceph_osdc_new_request()
(it gets provided to ceph_osdc_build_request()).  And rather than
passing a do_sync flag, have the number of ops in the ops array
supplied imply adding a second STARTSYNC operation after the READ or
WRITE requested.

This and some of the patches that follow are related to having the
messenger (only) be responsible for filling the content of the
message header, as described here:
    http://tracker.ceph.com/issues/4589

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:17:58 -07:00
Alex Elder 25d71cb92d ceph: use page_offset() in ceph_writepages_start()
There's one spot in ceph_writepages_start() that open-codes what
page_offset() does safely.  Use the macro so we don't have to worry
about wrapping.

This resolves:
    http://tracker.ceph.com/issues/4648

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:17:53 -07:00
Alex Elder e0c594878e libceph: record byte count not page count
Record the byte count for an osd request rather than the page count.
The number of pages can always be derived from the byte count (and
alignment/offset) but the reverse is not true.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:16:36 -07:00
Alex Elder 0fff87ec79 libceph: separate read and write data
An osd request defines information about where data to be read
should be placed as well as where data to write comes from.
Currently these are represented by common fields.

Keep information about data for writing separate from data to be
read by splitting these into data_in and data_out fields.

This is the key patch in this whole series, in that it actually
identifies which osd requests generate outgoing data and which
generate incoming data.  It's less obvious (currently) that an osd
CALL op generates both outgoing and incoming data; that's the focus
of some upcoming work.

This resolves:
    http://tracker.ceph.com/issues/4127

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:16:27 -07:00
Alex Elder 2ac2b7a6d4 libceph: distinguish page and bio requests
An osd request uses either pages or a bio list for its data.  Use a
union to record information about the two, and add a data type
tag to select between them.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:16:25 -07:00
Alex Elder 2794a82a11 libceph: separate osd request data info
Pull the fields in an osd request structure that define the data for
the request out into a separate structure.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:16:24 -07:00
Alex Elder 153e5167e0 libceph: don't assign page info in ceph_osdc_new_request()
Currently ceph_osdc_new_request() assigns an osd request's
r_num_pages and r_alignment fields.  The only thing it does
after that is call ceph_osdc_build_request(), and that doesn't
need those fields to be assigned.

Move the assignment of those fields out of ceph_osdc_new_request()
and into its caller.  As a result, the page_align parameter is no
longer used, so get rid of it.

Note that in ceph_sync_write(), the value for req->r_num_pages had
already been calculated earlier (as num_pages, and fortunately
it was computed the same way).  So don't bother recomputing it,
but because it's not needed earlier, move that calculation after the
call to ceph_osdc_new_request().  Hold off making the assignment to
r_alignment, doing it instead r_pages and r_num_pages are
getting set.

Similarly, in start_read(), nr_pages already holds the number of
pages in the array (and is calculated the same way), so there's no
need to recompute it.  Move the assignment of the page alignment
down with the others there as well.

This and the next few patches are preparation work for:
    http://tracker.ceph.com/issues/4127

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:16:23 -07:00
Alex Elder cf7b7e1492 ceph: use calc_pages_for() in start_read()
There's a spot that computes the number of pages to allocate for a
page-aligned length by just shifting it.  Use calc_pages_for()
instead, to be consistent with usage everywhere else.  The result
is the same.

The reason for this is to make it clearer in an upcoming patch that
this calculation is duplicated.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-05-01 21:16:21 -07:00
Sage Weil 7971bd92ba ceph: revert commit 22cddde104
commit 22cddde104 breaks the atomicity of write operation, it also
introduces a deadlock between write and truncate.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>

Conflicts:
	fs/ceph/addr.c
2013-05-01 21:15:58 -07:00
Linus Torvalds 1cf0209c43 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
Pull Ceph updates from Sage Weil:
 "A few groups of patches here.  Alex has been hard at work improving
  the RBD code, layout groundwork for understanding the new formats and
  doing layering.  Most of the infrastructure is now in place for the
  final bits that will come with the next window.

  There are a few changes to the data layout.  Jim Schutt's patch fixes
  some non-ideal CRUSH behavior, and a set of patches from me updates
  the client to speak a newer version of the protocol and implement an
  improved hashing strategy across storage nodes (when the server side
  supports it too).

  A pair of patches from Sam Lang fix the atomicity of open+create
  operations.  Several patches from Yan, Zheng fix various mds/client
  issues that turned up during multi-mds torture tests.

  A final set of patches expose file layouts via virtual xattrs, and
  allow the policies to be set on directories via xattrs as well
  (avoiding the awkward ioctl interface and providing a consistent
  interface for both kernel mount and ceph-fuse users)."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client: (143 commits)
  libceph: add support for HASHPSPOOL pool flag
  libceph: update osd request/reply encoding
  libceph: calculate placement based on the internal data types
  ceph: update support for PGID64, PGPOOL3, OSDENC protocol features
  ceph: update "ceph_features.h"
  libceph: decode into cpu-native ceph_pg type
  libceph: rename ceph_pg -> ceph_pg_v1
  rbd: pass length, not op for osd completions
  rbd: move rbd_osd_trivial_callback()
  libceph: use a do..while loop in con_work()
  libceph: use a flag to indicate a fault has occurred
  libceph: separate non-locked fault handling
  libceph: encapsulate connection backoff
  libceph: eliminate sparse warnings
  ceph: eliminate sparse warnings in fs code
  rbd: eliminate sparse warnings
  libceph: define connection flag helpers
  rbd: normalize dout() calls
  rbd: barriers are hard
  rbd: ignore zero-length requests
  ...
2013-02-28 17:43:09 -08:00
Sage Weil 1b83bef24c libceph: update osd request/reply encoding
Use the new version of the encoding for osd requests and replies.  In the
process, update the way we are tracking request ops and reply lengths and
results in the struct ceph_osd_request.  Update the rbd and fs/ceph users
appropriately.

The main changes are:
 - we keep pointers into the request memory for fields we need to update
   each time the request is sent out over the wire
 - we keep information about the result in an array in the request struct
   where the users can easily get at it.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
2013-02-26 15:02:50 -08:00
Al Viro 496ad9aa8e new helper: file_inode(file)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22 23:31:31 -05:00
Alex Elder a3bea47e8b ceph: kill ceph_osdc_new_request() "num_reply" parameter
The "num_reply" parameter to ceph_osdc_new_request() is never
used inside that function, so get rid of it.

Note that ceph_sync_write() passes 2 for that argument, while all
other callers pass 1.  It doesn't matter, but perhaps someone should
verify this doesn't indicate a problem.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-02-18 12:19:39 -06:00
Alex Elder 2480882611 ceph: kill ceph_osdc_writepages() "flags" parameter
There is only one caller of ceph_osdc_writepages(), and it always
passes 0 as its "flags" argument.  Get rid of that argument and
replace its use in ceph_osdc_writepages() with 0.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-02-18 12:19:35 -06:00
Alex Elder fbf8685fb1 ceph: kill ceph_osdc_writepages() "dosync" parameter
There is only one caller of ceph_osdc_writepages(), and it always
passes 0 as its "dosync" argument.  Get rid of that argument and
replace its use in ceph_osdc_writepages() with 0.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-02-18 12:19:28 -06:00
Alex Elder 87f979d390 ceph: kill ceph_osdc_writepages() "nofail" parameter
There is only one caller of ceph_osdc_writepages(), and it always
passes the value true as its "nofail" argument.  Get rid of that
argument and replace its use in ceph_osdc_writepages() with the
constant value true.

This and a number of cleanup patches that follow resolve:
    http://tracker.ceph.com/issues/4126

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-02-18 12:19:22 -06:00
Linus Torvalds 40889e8d9f Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
Pull Ceph update from Sage Weil:
 "There are a few different groups of commits here.  The largest is
  Alex's ongoing work to enable the coming RBD features (cloning,
  striping).  There is some cleanup in libceph that goes along with it.

  Cyril and David have fixed some problems with NFS reexport (leaking
  dentries and page locks), and there is a batch of patches from Yan
  fixing problems with the fs client when running against a clustered
  MDS.  There are a few bug fixes mixed in for good measure, many of
  which will be going to the stable trees once they're upstream.

  My apologies for the late pull.  There is still a gremlin in the rbd
  map/unmap code and I was hoping to include the fix for that as well,
  but we haven't been able to confirm the fix is correct yet; I'll send
  that in a separate pull once it's nailed down."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client: (68 commits)
  rbd: get rid of rbd_{get,put}_dev()
  libceph: register request before unregister linger
  libceph: don't use rb_init_node() in ceph_osdc_alloc_request()
  libceph: init event->node in ceph_osdc_create_event()
  libceph: init osd->o_node in create_osd()
  libceph: report connection fault with warning
  libceph: socket can close in any connection state
  rbd: don't use ENOTSUPP
  rbd: remove linger unconditionally
  rbd: get rid of RBD_MAX_SEG_NAME_LEN
  libceph: avoid using freed osd in __kick_osd_requests()
  ceph: don't reference req after put
  rbd: do not allow remove of mounted-on image
  libceph: Unlock unprocessed pages in start_read() error path
  ceph: call handle_cap_grant() for cap import message
  ceph: Fix __ceph_do_pending_vmtruncate
  ceph: Don't add dirty inode to dirty list if caps is in migration
  ceph: Fix infinite loop in __wake_requests
  ceph: Don't update i_max_size when handling non-auth cap
  bdi_register: add __printf verification, fix arg mismatch
  ...
2012-12-20 14:00:13 -08:00
David Zafman 8884d53dd6 libceph: Unlock unprocessed pages in start_read() error path
Function start_read() can get an error before processing all pages.
It must not only release the remaining pages, but unlock them too.

This fixes http://tracker.newdream.net/issues/3370

Signed-off-by: David Zafman <david.zafman@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
2012-12-13 08:13:09 -06:00
Sage Weil 22cddde104 ceph: Fix i_size update race
ceph_aio_write() has an optimization that marks cap EPH_CAP_FILE_WR
dirty before data is copied to page cache and inode size is updated.
If ceph_check_caps() flushes the dirty cap before the inode size is
updated, MDS can miss the new inode size. The fix is move
ceph_{get,put}_cap_refs() into ceph_write_{begin,end}() and call
__ceph_mark_dirty_caps() after inode size is updated.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Sage Weil <sage@inktank.com>
2012-11-05 11:07:23 -08:00
Konstantin Khlebnikov 0b173bc4da mm: kill vma flag VM_CAN_NONLINEAR
Move actual pte filling for non-linear file mappings into the new special
vma operation: ->remap_pages().

Filesystems must implement this method to get non-linear mapping support,
if it uses filemap_fault() then generic_file_remap_pages() can be used.

Now device drivers can implement this method and obtain nonlinear vma support.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>	#arch/tile
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Venkatesh Pallipadi <venki@google.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09 16:22:17 +09:00
Alex Elder 6285bc2312 ceph: avoid 32-bit page index overflow
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>
2012-10-03 10:51:18 -05:00
Sage Weil 6816282dab ceph: propagate layout error on osd request creation
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>
2012-10-01 17:20:00 -05:00
Jan Kara 3ca9c3bd8a ceph: Push file_update_time() into ceph_page_mkwrite()
CC: Sage Weil <sage@newdream.net>
CC: ceph-devel@vger.kernel.org
Acked-by: Sage Weil <sage@newdream.net>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-31 01:02:45 +04:00
Yan, Zheng 61600ef848 ceph: check PG_Private flag before accessing page->private
I got lots of NULL pointer dereference Oops when compiling kernel on ceph.
The bug is because the kernel page migration routine replaces some pages
in the page cache with new pages, these new pages' private can be non-zero.

Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
Signed-off-by: Sage Weil <sage@inktank.com>
(cherry picked from commit 28c0254ede)
2012-06-20 07:43:48 -05:00
Sage Weil be655596b3 ceph: use i_ceph_lock instead of i_lock
We have been using i_lock to protect all kinds of data structures in the
ceph_inode_info struct, including lists of inodes that we need to iterate
over while avoiding races with inode destruction.  That requires grabbing
a reference to the inode with the list lock protected, but igrab() now
takes i_lock to check the inode flags.

Changing the list lock ordering would be a painful process.

However, using a ceph-specific i_ceph_lock in the ceph inode instead of
i_lock is a simple mechanical change and avoids the ordering constraints
imposed by igrab().

Reported-by: Amon Ott <a.ott@m-privacy.de>
Signed-off-by: Sage Weil <sage@newdream.net>
2011-12-07 10:46:44 -08:00
Sage Weil 3395734067 libceph: fix double-free of page vector
ceph_release_page_vector() kfrees the vector; we shouldn't do it here too.

Reported-by: Jeff Wu <cpwu@tnsoft.com.cn>
Signed-off-by: Sage Weil <sage@newdream.net>
2011-10-25 16:10:17 -07:00
Sage Weil 0d66a487c1 ceph: implement (optional) max read size
The 'rsize' mount option limits the maximum size of an individual
read(ahead) operation that is sent off to an OSD.  This is distinct from
'rasize', which controls the size of the readahead window.

Signed-off-by: Sage Weil <sage@newdream.net>
2011-10-25 16:10:15 -07:00
Sage Weil 7c272194e6 ceph: make readpages fully async
When we get a ->readpages() aop, submit async reads for all page ranges
in the provided page list.  Lock the pages immediately, so that VFS/MM
will block until the reads complete.

Signed-off-by: Sage Weil <sage@newdream.net>
2011-10-25 16:10:14 -07:00
Sage Weil 70b666c3b4 ceph: use ihold when we already have an inode ref
We should use ihold whenever we already have a stable inode ref, even
when we aren't holding i_lock.  This avoids adding new and unnecessary
locking dependencies.

Signed-off-by: Sage Weil <sage@newdream.net>
2011-06-07 21:34:11 -07:00
Sage Weil 9d6fcb081a ceph: check return value for start_request in writepages
Since we pass the nofail arg, we should never get an error; BUG if we do.
(And fix the function to not return an error if __map_request fails.)

Signed-off-by: Sage Weil <sage@newdream.net>
2011-05-19 11:25:05 -07:00
Sage Weil 6b4a3b517a ceph: remove useless check
rc is only ever 0 or negative in this method.

Signed-off-by: Sage Weil <sage@newdream.net>
2011-05-19 11:25:05 -07:00
Henry C Chang 8c71897be2 ceph: handle ceph_osdc_new_request failure in ceph_writepages_start
We should unlock the page and return -ENOMEM if ceph_osdc_new_request
failed.

Signed-off-by: Henry C Chang <henry_c_chang@tcloudcomputing.com>
Signed-off-by: Sage Weil <sage@newdream.net>
2011-05-03 09:28:12 -07:00
Lucas De Marchi 25985edced Fix common misspellings
Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-31 11:26:23 -03:00
Dave Chinner 0444d76ae6 fs: don't use igrab() while holding i_lock
Fix the incorrect use of igrab() inside the i_lock in NFS and Ceph‥

If we are already holding the i_lock, we have a reference to the
inode so we can safely use ihold() to gain an extra reference. This
avoids hangs due to lock recursion on the i_lock now that the
inode_lock is gone and igrab() uses the i_lock itself.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-29 07:50:34 -07:00
Linus Torvalds 76db8ac45f Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph: fix readdir EOVERFLOW on 32-bit archs
  ceph: fix frag offset for non-leftmost frags
  ceph: fix dangling pointer
  ceph: explicitly specify page alignment in network messages
  ceph: make page alignment explicit in osd interface
  ceph: fix comment, remove extraneous args
  ceph: fix update of ctime from MDS
  ceph: fix version check on racing inode updates
  ceph: fix uid/gid on resent mds requests
  ceph: fix rdcache_gen usage and invalidate
  ceph: re-request max_size if cap auth changes
  ceph: only let auth caps update max_size
  ceph: fix open for write on clustered mds
  ceph: fix bad pointer dereference in ceph_fill_trace
  ceph: fix small seq message skipping
  Revert "ceph: update issue_seq on cap grant"
2010-11-19 15:32:22 -08:00
Sage Weil b7495fc2ff ceph: make page alignment explicit in osd interface
We used to infer alignment of IOs within a page based on the file offset,
which assumed they matched.  This broke with direct IO that was not aligned
to pages (e.g., 512-byte aligned IO).  We were also trusting the alignment
specified in the OSD reply, which could have been adjusted by the server.

Explicitly specify the page alignment when setting up OSD IO requests.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-11-09 12:43:12 -08:00
Wu Fengguang 1b430beee5 writeback: remove nonblocking/encountered_congestion references
This removes more dead code that was somehow missed by commit 0d99519efe
(writeback: remove unused nonblocking and congestion checks).  There are
no behavior change except for the removal of two entries from one of the
ext4 tracing interface.

The nonblocking checks in ->writepages are no longer used because the
flusher now prefer to block on get_request_wait() than to skip inodes on
IO congestion.  The latter will lead to more seeky IO.

The nonblocking checks in ->writepage are no longer used because it's
redundant with the WB_SYNC_NONE check.

We no long set ->nonblocking in VM page out and page migration, because
a) it's effectively redundant with WB_SYNC_NONE in current code
b) it's old semantic of "Don't get stuck on request queues" is mis-behavior:
   that would skip some dirty inodes on congestion and page out others, which
   is unfair in terms of LRU age.

Inspired by Christoph Hellwig. Thanks!

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: David Howells <dhowells@redhat.com>
Cc: Sage Weil <sage@newdream.net>
Cc: Steve French <sfrench@samba.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 16:52:05 -07:00
Yehuda Sadeh 3d14c5d2b6 ceph: factor out libceph from Ceph file system
This factors out protocol and low-level storage parts of ceph into a
separate libceph module living in net/ceph and include/linux/ceph.  This
is mostly a matter of moving files around.  However, a few key pieces
of the interface change as well:

 - ceph_client becomes ceph_fs_client and ceph_client, where the latter
   captures the mon and osd clients, and the fs_client gets the mds client
   and file system specific pieces.
 - Mount option parsing and debugfs setup is correspondingly broken into
   two pieces.
 - The mon client gets a generic handler callback for otherwise unknown
   messages (mds map, in this case).
 - The basic supported/required feature bits can be expanded (and are by
   ceph_fs_client).

No functional change, aside from some subtle error handling cases that got
cleaned up in the refactoring process.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-10-20 15:37:28 -07:00
Sage Weil ae00d4f37f ceph: fix cap_snap and realm split
The cap_snap creation/queueing relies on both the current i_head_snapc
_and_ the i_snap_realm pointers being correct, so that the new cap_snap
can properly reference the old context and the new i_head_snapc can be
updated to reference the new snaprealm's context.  To fix this, we:

 - move inodes completely to the new (split) realm so that i_snap_realm
   is correct, and
 - generate the new snapc's _before_ queueing the cap_snaps in
   ceph_update_snap_trace().

Signed-off-by: Sage Weil <sage@newdream.net>
2010-09-16 16:26:51 -07:00
Sage Weil a77d9f7dce ceph: fix file offset wrapping at 4GB on 32-bit archs
Cast the value before shifting so that we don't run out of bits with a
32-bit unsigned long.  This fixes wrapping of high file offsets into the
low 4GB of a file on disk, and the subsequent data corruption for large
files.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-09-11 10:55:25 -07:00
Sage Weil 7d8cb26d7d ceph: maintain i_head_snapc when any caps are dirty, not just for data
We used to use i_head_snapc to keep track of which snapc the current epoch
of dirty data was dirtied under.  It is used by queue_cap_snap to set up
the cap_snap.  However, since we queue cap snaps for any dirty caps, not
just for dirty file data, we need to keep a valid i_head_snapc anytime
we have dirty|flushing caps.  This fixes a NULL pointer deref in
queue_cap_snap when writing back dirty caps without data (e.g.,
snaptest-authwb.sh).

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-24 16:24:18 -07:00
Michael Rubin 679ceace84 mm: exporting account_page_dirty
This allows code outside of the mm core to safely manipulate page state
and not worry about the other accounting. Not using these routines means
that some code will lose track of the accounting and we get bugs. This
has happened once already.

Signed-off-by: Michael Rubin <mrubin@google.com>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-22 15:16:51 -07:00
Sage Weil 213c99ee0c ceph: whitespace cleanup
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-03 10:25:11 -07:00
Sage Weil 2962507ca2 ceph: perform lazy reads when file mode and caps permit
If the file mode is marked as "lazy," perform cached/buffered reads when
the caps permit it.  Adjust the rdcache_gen and invalidation logic
accordingly so that we manage our cache based on the FILE_CACHE -or-
FILE_LAZYIO cap bits.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:39 -07:00
Cheng Renquan 640ef79d27 ceph: use ceph_sb_to_client instead of ceph_client
ceph_sb_to_client and ceph_client are really identical, we need to dump
one; while function ceph_client is confusing with "struct ceph_client",
ceph_sb_to_client's definition is more clear; so we'd better switch all
call to ceph_sb_to_client.

  -static inline struct ceph_client *ceph_client(struct super_block *sb)
  -{
  -	return sb->s_fs_info;
  -}

Signed-off-by: Cheng Renquan <crquan@gmail.com>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:17 -07:00
Yehuda Sadeh 31459fe4b2 ceph: use __page_cache_alloc and add_to_page_cache_lru
Following Nick Piggin patches in btrfs, pagecache pages should be
allocated with __page_cache_alloc, so they obey pagecache memory
policies.

Also, using add_to_page_cache_lru instead of using a private
pagevec where applicable.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-17 15:25:12 -07:00
Sage Weil 54ad023ba8 ceph: don't use writeback_control in writepages completion
The ->writepages writeback_control is not still valid in the writepages
completion.  We were touching it solely to adjust pages_skipped when there
was a writeback error (EIO, ENOSPC, EPERM due to bad osd credentials),
causing an oops in the writeback code shortly thereafter.  Updating
pages_skipped on error isn't correct anyway, so let's just rip out this
(clearly broken) code to pass the wbc to the completion.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-05 21:31:40 -07:00
Sage Weil 7ff899da02 ceph: fix lockless caps check
The __ variant requires caller to hold i_lock.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-05-03 10:49:25 -07:00
Linus Torvalds 96e35b40c0 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph: use separate class for ceph sockets' sk_lock
  ceph: reserve one more caps space when doing readdir
  ceph: queue_cap_snap should always queue dirty context
  ceph: fix dentry reference leak in dcache readdir
  ceph: decode v5 of osdmap (pool names) [protocol change]
  ceph: fix ack counter reset on connection reset
  ceph: fix leaked inode ref due to snap metadata writeback race
  ceph: fix snap context reference leaks
  ceph: allow writeback of snapped pages older than 'oldest' snapc
  ceph: fix dentry rehashing on virtual .snap dir
2010-04-14 18:45:31 -07:00
Sage Weil 6298a33757 ceph: fix snap context reference leaks
The get_oldest_context() helper takes a reference to the returned snap
context, but most callers weren't dropping that reference.  Fix them.

Also drop the unused locked __get_oldest_context() variant.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-04-01 09:34:37 -07:00
Sage Weil 80e755fede ceph: allow writeback of snapped pages older than 'oldest' snapc
On snap deletion, we don't regenerate ceph_cap_snaps for inodes with dirty
pages because deletion does not affect metadata writeback.  However, we
did run into problems when we went to write back the pages because the
'oldest' snapc is determined by the oldest cap_snap, and that may be the
newer snapc that reflects the deletion.  This caused confusion and an
infinite loop in ceph_update_writeable_page().

Change the snapc checks to allow writeback of any snapc that is equal to
OR older than the 'oldest' snapc.

When there are no cap_snaps, we were also using the realm's latest snapc
for writeback, which complicates ceph_put_wrbufffer_cap_refs().  Instead,
use i_head_snapc, the most snapc used for the most recent ('head') data.
This makes the writeback snapc (ceph_osd_request.r_snapc) _always_ match a
capsnap or i_head_snapc.

Also, in writepags_finish(), drop the snapc referenced by the _page_
and do not assume it matches the request snapc (it may not anymore).

Signed-off-by: Sage Weil <sage@newdream.net>
2010-04-01 09:34:36 -07:00
Tejun Heo 5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Sage Weil 8f883c24de ceph: make write_begin wait propagate ERESTARTSYS
Currently, if the wait_event_interruptible is interrupted, we
return EAGAIN unconditionally and loop, such that we aren't, in
fact, interruptible.  So, propagate ERESTARTSYS if we get it.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-03-23 07:47:03 -07:00
Alexander Beregalov 4ce1e9adab ceph: move dereference after NULL test
Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-23 14:26:34 -08:00
Yehuda Sadeh e63dc5c780 ceph: remove page upon writeback completion if lost cache cap
This page should have been removed earlier when the cache cap was
revoked, but a writeback was in flight, so it was skipped. We truncate
it here just as the writeback finishes, while it's still locked.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-19 14:34:18 -08:00
Sage Weil 3c6f6b79a6 ceph: cleanup async writeback, truncation, invalidate helpers
Grab inode ref in helper.  Make work functions static, with consistent
naming.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-11 11:48:54 -08:00
Yehuda Sadeh 4af6b2257e ceph: refactor ceph_write_begin, fix ceph_page_mkwrite
Originally ceph_page_mkwrite called ceph_write_begin, hoping that
the returned locked page would be the page that it was requested
to mkwrite. Factored out relevant part of ceph_page_mkwrite and
we lock the right page anyway.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-11 11:48:50 -08:00
Yehuda Sadeh b056c8769d ceph: remove unused variable
Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-11 11:48:48 -08:00
Sage Weil 79788c698b ceph: release all pages after successful osd write response
We release all the pages, even if the osd response was
different than the number of pages written. This could only
happen due to truncation that arrives the osd in
different order, for which we want the pages released anyway.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-02-02 16:34:04 -08:00
Julia Lawall ec7384ec23 ceph: remove duplicate variable initialization
The variable client is initialized twice to the same (side effect-free)
expression.  Drop one initialization.

A simplified version of the semantic match that finds this problem is:
(http://coccinelle.lip6.fr/)

// <smpl>
@forall@
idexpression *x;
identifier f!=ERR_PTR;
@@

x = f(...)
... when != x
(
x = f(...,<+...x...+>,...)
|
* x = f(...)
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-01-25 11:33:35 -08:00
Yehuda Sadeh 2baba25019 ceph: writeback congestion control
Set bdi congestion bit when amount of write data in flight exceeds adjustable
threshold.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2009-12-21 16:39:56 -08:00
Yehuda Sadeh dbd646a851 ceph: writepage grabs and releases inode
Fixes a deadlock that is triggered due to kswapd,
while the page was locked and the iput couldn't tear
down the address space.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
2009-12-21 16:39:56 -08:00
Sage Weil 6b8051855d ceph: allocate and parse mount args before client instance
This simplifies much of the error handling during mount.  It also means
that we have the mount args before client creation, and we can initialize
based on those options.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-10-27 11:57:03 -07:00
Sage Weil 1d3576fd10 ceph: address space operations
The ceph address space methods are concerned primarily with managing
the dirty page accounting in the inode, which (among other things)
must keep track of which snapshot context each page was dirtied in,
and ensure that dirty data is written out to the OSDs in snapshort
order.

A writepage() on a page that is not currently writeable due to
snapshot writeback ordering constraints is ignored (it was presumably
called from kswapd).

Signed-off-by: Sage Weil <sage@newdream.net>
2009-10-06 11:31:09 -07:00