The default behavior for directory reservations stays the same, but we add a
mount option so people can tweak the size of directory reservations
according to their workloads.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
The default reservation size of 4 (32-bit windows) is a bit too ambitious.
Scale it back to 16 bits (resv_level=2). I have been testing various sizes
on a 4-node cluster which runs a mixed workload that is heavily threaded.
With a 256MB local alloc, I get *roughly* the following levels of average file
fragmentation:
resv_level=0 70%
resv_level=1 21%
resv_level=2 23%
resv_level=3 24%
resv_level=4 60%
resv_level=5 did not test
resv_level=6 60%
resv_level=2 seemed like a good compromise between not letting windows be
too small, but not so big that heavier workloads will immediately suffer
without tuning.
This patch also change the behavior of directory reservations - they now
track file reservations. The previous compromise of giving directory
windows only 8 bits wound up fragmenting more at some window sizes because
file allocations had smaller unused windows to poach from.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
I have observed that the current size of 8M gives us pretty poor
fragmentation on multi-threaded workloads which do lots of writes.
Generally, I can increase the size of local alloc windows and observe a
marked decrease in fragmentation, even up and beyond window sizes of 512
megabytes. This makes sense for a couple reasons - larger local alloc means
more room for reservation windows. On multi-node workloads the larger local
alloc helps as well because we don't have to do window slides as often.
Also, I removed the OCFS2_DEFAULT_LOCAL_ALLOC_SIZE constant as it is no
longer used and the comment above it was out of date.
To test fragmentation, I used a workload which launched 4 threads that did
4k writes into a series of about 140 alternating files.
With resv_level=2, and a 4k/4k file system I observed the following average
fragmentation for various localalloc= parameters:
localalloc= avg. fragmentation
8 48
32 16
64 10
120 7
On larger cluster sizes, the difference is more dramatic.
The new default size top out at 256M, which we'll only get for cluster
sizes of 32K and above.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
This patch pulls the local alloc sizing code into localalloc.c and provides
a callout to it from ocfs2_fill_super(). Behavior is essentially unchanged
except that I correctly calculate the maximum local alloc size. The old code
in ocfs2_parse_options() calculated the max size as:
ocfs2_local_alloc_size(sb) * 8
which is correct, in bits. Unfortunately though the option passed in is in
megabytes. Ultimately, this bug made no real difference - the shrink code
would catch a too-large size and bring it down to something reasonable.
Still, it's less than efficient as-is.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Inodes are always allocated from the global bitmap now so we don't need this
any more. Also, the existing implementation bounces reservations around
needlessly.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Otherwise, the need for a very large contiguous allocation tends to
wreak havoc on many inode allocation reservations on the local alloc, thus
ruining any chances for contiguousness.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Use the reservations system for unindexed dir tree allocations. We don't
bother with the indexed tree as reads from it are mostly random anyway.
Directory reservations are marked seperately, to allow the reservations code
a chance to optimize their window sizes. This patch allocates only 8 bits
for directory windows as they generally are not expected to grow as quickly
as file data. Future improvements to dir window sizing can trivially be
made.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
This patch improves Ocfs2 allocation policy by allowing an inode to
reserve a portion of the local alloc bitmap for itself. The reserved
portion (allocation window) is advisory in that other allocation
windows might steal it if the local alloc bitmap becomes
full. Otherwise, the reservations are honored and guaranteed to be
free. When the local alloc window is moved to a different portion of
the bitmap, existing reservations are discarded.
Reservation windows are represented internally by a red-black
tree. Within that tree, each node represents the reservation window of
one inode. An LRU of active reservations is also maintained. When new
data is written, we allocate it from the inodes window. When all bits
in a window are exhausted, we allocate a new one as close to the
previous one as possible. Should we not find free space, an existing
reservation is pulled off the LRU and cannibalized.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
jbd[2]_journal_dirty_metadata() only returns 0. It's been returning 0
since before the kernel moved to git. There is no point in checking
this error.
ocfs2_journal_dirty() has been faithfully returning the status since the
beginning. All over ocfs2, we have blocks of code checking this can't
fail status. In the past few years, we've tried to avoid adding these
checks, because they are pointless. But anyone who looks at our code
assumes they are needed.
Finally, ocfs2_journal_dirty() is made a void function. All error
checking is removed from other files. We'll BUG_ON() the status of
jbd2_journal_dirty_metadata() just in case they change it someday. They
won't.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
When the local alloc file changes windows, unused bits are freed back to the
global bitmap. By defnition, those bits can not be in use by any file. Also,
the local alloc will never have been able to allocate those bits if they
were part of a previous truncate. Therefore it makes sense that we should
clear unused local alloc bits in the undo buffer so that they can be used
immediatly.
[ Modified to call it ocfs2_release_clusters() -- Joel ]
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
You can't store a pointer that you haven't filled in yet and expect it
to work.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
When replacing a xattr's value, in some case we wipe its name/value
first and then re-add it. The wipe is done by
ocfs2_xa_block_wipe_namevalue() when the xattr is in the inode or
block. We currently adjust name_offset for all the entries which have
(offset < name_offset). This does not adjust the entrie we're replacing.
Since we are replacing the entry, we don't adjust the total entry count.
When we calculate a new namevalue location, we trust the entries
now-wrong offset in ocfs2_xa_get_free_start(). The solution is to
also adjust the name_offset for the replaced entry, allowing
ocfs2_xa_get_free_start() to calculate the new namevalue location
correctly.
The following script can trigger a kernel panic easily.
echo 'y'|mkfs.ocfs2 --fs-features=local,xattr -b 4K $DEVICE
mount -t ocfs2 $DEVICE $MNT_DIR
FILE=$MNT_DIR/$RANDOM
for((i=0;i<76;i++))
do
string_76="a$string_76"
done
string_78="aa$string_76"
string_82="aaaa$string_78"
touch $FILE
setfattr -n 'user.test1234567890' -v $string_76 $FILE
setfattr -n 'user.test1234567890' -v $string_78 $FILE
setfattr -n 'user.test1234567890' -v $string_82 $FILE
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
What we were doing before was to ask for the current window size as the
maximum allocation. This had the effect of limiting the amount of allocation
we could get for the local alloc during times when the window size was
shrunk due to fragmentation. In some cases, that could actually *increase*
fragmentation by artificially limiting the number of bits we can accept. So
while we still want to ask for a minimum number of bits equal to window
size, there is no reason why we should limit the number of bits the local
alloc should accept. Hence always allow the maximum number of local alloc
bits.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
ocfs2_set_acl() and ocfs2_init_acl() were setting i_mode on the in-memory
inode, but never setting it on the disk copy. Thus, acls were some times not
getting propagated between nodes. This patch fixes the issue by adding a
helper function ocfs2_acl_set_mode() which does this the right way.
ocfs2_set_acl() and ocfs2_init_acl() are then updated to call
ocfs2_acl_set_mode().
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
In reflink, we need to upate i_blocks for the target inode.
Reported-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
In ocfs2_validate_gd_parent, we check bg_chain against the
cl_next_free_rec of the dinode. Actually in resize, we have
the chance of bg_chain == cl_next_free_rec. So add some
additional condition check for it.
I also rename paramter "clean_error" to "resize", since the
old one is not clearly enough to indicate that we should only
meet with this case in resize.
btw, the correpsonding bug is
http://oss.oracle.com/bugzilla/show_bug.cgi?id=1230.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
ocfs2_lock() will skip locks on file which has mode set to 02666. This
is a problem in cases where the mode of the file is changed after a
process has obtained a lock on the file.
ocfs2_lock() should skip the check for mandatory locks when unlocking a
file.
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (56 commits)
doc: fix typo in comment explaining rb_tree usage
Remove fs/ntfs/ChangeLog
doc: fix console doc typo
doc: cpuset: Update the cpuset flag file
Fix of spelling in arch/sparc/kernel/leon_kernel.c no longer needed
Remove drivers/parport/ChangeLog
Remove drivers/char/ChangeLog
doc: typo - Table 1-2 should refer to "status", not "statm"
tree-wide: fix typos "ass?o[sc]iac?te" -> "associate" in comments
No need to patch AMD-provided drivers/gpu/drm/radeon/atombios.h
devres/irq: Fix devm_irq_match comment
Remove reference to kthread_create_on_cpu
tree-wide: Assorted spelling fixes
tree-wide: fix 'lenght' typo in comments and code
drm/kms: fix spelling in error message
doc: capitalization and other minor fixes in pnp doc
devres: typo fix s/dev/devm/
Remove redundant trailing semicolons from macros
fix typo "definetly" -> "definitely" in comment
tree-wide: s/widht/width/g typo in comments
...
Fix trivial conflict in Documentation/laptops/00-INDEX
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Acked-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Constify struct sysfs_ops.
This is part of the ops structure constification
effort started by Arjan van de Ven et al.
Benefits of this constification:
* prevents modification of data that is shared
(referenced) by many other structure instances
at runtime
* detects/prevents accidental (but not intentional)
modification attempts on archs that enforce
read-only kernel data at runtime
* potentially better optimized code as the compiler
can assume that the const data cannot be changed
* the compiler/linker move const data into .rodata
and therefore exclude them from false sharing
Signed-off-by: Emese Revfy <re.emese@gmail.com>
Acked-by: David Teigland <teigland@redhat.com>
Acked-by: Matt Domsch <Matt_Domsch@dell.com>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Acked-by: Hans J. Koch <hjk@linutronix.de>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Rename for_each_bit to for_each_set_bit in the kernel source tree. To
permit for_each_clear_bit(), should that ever be added.
The patch includes a macro to map the old for_each_bit() onto the new
for_each_set_bit(). This is a (very) temporary thing to ease the migration.
[akpm@linux-foundation.org: add temporary for_each_bit()]
Suggested-by: Alexey Dobriyan <adobriyan@gmail.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Artem Bityutskiy <dedekind@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6: (33 commits)
quota: stop using QUOTA_OK / NO_QUOTA
dquot: cleanup dquot initialize routine
dquot: move dquot initialization responsibility into the filesystem
dquot: cleanup dquot drop routine
dquot: move dquot drop responsibility into the filesystem
dquot: cleanup dquot transfer routine
dquot: move dquot transfer responsibility into the filesystem
dquot: cleanup inode allocation / freeing routines
dquot: cleanup space allocation / freeing routines
ext3: add writepage sanity checks
ext3: Truncate allocated blocks if direct IO write fails to update i_size
quota: Properly invalidate caches even for filesystems with blocksize < pagesize
quota: generalize quota transfer interface
quota: sb_quota state flags cleanup
jbd: Delay discarding buffers in journal_unmap_buffer
ext3: quota_write cross block boundary behaviour
quota: drop permission checks from xfs_fs_set_xstate/xfs_fs_set_xquota
quota: split out compat_sys_quotactl support from quota.c
quota: split out netlink notification support from quota.c
quota: remove invalid optimization from quota_sync_all
...
Fixed trivial conflicts in fs/namei.c and fs/ufs/inode.c
Get rid of the initialize dquot operation - it is now always called from
the filesystem and if a filesystem really needs it's own (which none
currently does) it can just call into it's own routine directly.
Rename the now static low-level dquot_initialize helper to __dquot_initialize
and vfs_dq_init to dquot_initialize to have a consistent namespace.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently various places in the VFS call vfs_dq_init directly. This means
we tie the quota code into the VFS. Get rid of that and make the
filesystem responsible for the initialization. For most metadata operations
this is a straight forward move into the methods, but for truncate and
open it's a bit more complicated.
For truncate we currently only call vfs_dq_init for the sys_truncate case
because open already takes care of it for ftruncate and open(O_TRUNC) - the
new code causes an additional vfs_dq_init for those which is harmless.
For open the initialization is moved from do_filp_open into the open method,
which means it happens slightly earlier now, and only for regular files.
The latter is fine because we don't need to initialize it for operations
on special files, and we already do it as part of the namespace operations
for directories.
Add a dquot_file_open helper that filesystems that support generic quotas
can use to fill in ->open.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Get rid of the drop dquot operation - it is now always called from
the filesystem and if a filesystem really needs it's own (which none
currently does) it can just call into it's own routine directly.
Rename the now static low-level dquot_drop helper to __dquot_drop
and vfs_dq_drop to dquot_drop to have a consistent namespace.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently clear_inode calls vfs_dq_drop directly. This means
we tie the quota code into the VFS. Get rid of that and make the
filesystem responsible for the drop inside the ->clear_inode
superblock operation.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Get rid of the transfer dquot operation - it is now always called from
the filesystem and if a filesystem really needs it's own (which none
currently does) it can just call into it's own routine directly.
Rename the now static low-level dquot_transfer helper to __dquot_transfer
and vfs_dq_transfer to dquot_transfer to have a consistent namespace,
and make the new dquot_transfer return a normal negative errno value
which all callers expect.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Get rid of the alloc_inode and free_inode dquot operations - they are
always called from the filesystem and if a filesystem really needs
their own (which none currently does) it can just call into it's
own routine directly.
Also get rid of the vfs_dq_alloc/vfs_dq_free wrappers and always
call the lowlevel dquot_alloc_inode / dqout_free_inode routines
directly, which now lose the number argument which is always 1.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Get rid of the alloc_space, free_space, reserve_space, claim_space and
release_rsv dquot operations - they are always called from the filesystem
and if a filesystem really needs their own (which none currently does)
it can just call into it's own routine directly.
Move shared logic into the common __dquot_alloc_space,
dquot_claim_space_nodirty and __dquot_free_space low-level methods,
and rationalize the wrappers around it to move as much as possible
code into the common block for CONFIG_QUOTA vs not. Also rename
all these helpers to be named dquot_* instead of vfs_dq_*.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently we were adding ioctl cmds/structures for ocfs2 into ocfs2_fs.h
which was used for define ocfs2 on-disk layout. That sounds a little bit
confusing, and it may be quickly polluted espcially when growing the
ocfs2_info_request ioctls afterwards(it will grow i bet).
As a result, such OCFS2 IOCs do need to be placed somewhere other than
ocfs2_fs.h, a separated ocfs2_ioctl.h will be added to store such ioctl
structures and definitions which could also be used from userspace to
invoke ioctls call.
Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
This patch makes ocfs2 send SIGXFSZ if new file size exceeds the rlimit.
Processes may get SIGXFSZ on one node (in the cluster) while others will
not on another if file size limits are different on the two nodes.
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Make use of the newly added BASTS masklog to trace ASTs and BASTs in userdlm.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
This patch adds a new masklog and uses it allow tracing ASTs and BASTs
in the dlmglue layer. This has been found to be very useful in debugging
cluster locking issues.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
If a node down event happens while dlm shutdown in progress, dlm recovery
should be done before dlm is shutdown. We can't migrate unrecovered locks,
obviously. But dlm_reco_thread only does recovery if the dlm_state is
in DLM_CTXT_JOINED.
dlm_reco_thread should do recovery if dlm_state is in DLM_CTXT_JOINED or
DLM_CTXT_IN_SHUTDOWN.
Signed-off-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
In ocfs2_direct_IO_get_blocks, we only need to bug out
in case of we are going to write a recounted extent rec.
What a silly bug introduced by me!
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Cc: stable@kernel.org
This patch fixes a compiling warning in ocfs2_file_aio_write().
Signed-off-by: Coly Li <coly.li@suse.de>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Unlike ocfs2, dlmfs has no permanent storage. It can't store off a
cluster stack it is supposed to be using. So it can't specify the stack
name in ocfs2_cluster_connect().
Instead, we create ocfs2_cluster_connect_agnostic(), which simply uses
the stack that is currently enabled. This is find for dlmfs, which will
rely on the stack initialization.
We add the "stackglue" capability to dlmfs's capability list. This lets
userspace know dlmfs can be used with all cluster stacks.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Rather than directly using o2dlm, dlmfs can now use the stackglue. This
allows it to use userspace cluster stacks and fs/dlm. This commit
forces o2cb for now. A latter commit will bump the protocol version and
allow non-o2cb stacks.
This is one big sed, really. LKM_xxMODE becomes DLM_LOCK_xx. LKM_flag
becomes DLM_LKF_flag.
We also learn to check that the LVB is valid before reading it. Any DLM
can lose the contents of the LVB during a complicated recovery. userdlm
should be checking this. Now it does. dlmfs will return 0 from read(2)
if the LVB was invalid.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
We want folks using dlmfs to be able to use the LVB in places other than
just write(2)/read(2). By ignoring truncate requests, we allow 'echo
"contents" > /dlm/space/lockname' to work.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Inside the stackglue, the locking protocol structure is hanging off of
the ocfs2_cluster_connection. This takes it one further; the locking
protocol is passed into ocfs2_cluster_connect(). Now different cluster
connections can have different locking protocols with distinct asts.
Note that all locking protocols have to keep their maximum protocol
version in lock-step.
With the protocol structure set in ocfs2_cluster_connect(), there is no
need for the stackglue to have a static pointer to a specific protocol
structure. We can change initialization to only pass in the maximum
protocol version.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
With the full ocfs2_locking_protocol hanging off of the
ocfs2_cluster_connection, ast wrappers can get the ast/bast pointers
there. They don't need to get them from their plugin structure.
The user plugin still needs the maximum locking protocol version,
though. This changes the plugin structure so that it only holds the max
version, not the entire ocfs2_locking_protocol pointer.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
With the ocfs2_cluster_connection hanging off of the ocfs2_dlm_lksb, we
have access to it in the ast and bast wrapper functions. Attach the
ocfs2_locking_protocol to the conn.
Now, instead of refering to a static variable for ast/bast pointers, the
wrappers can look at the connection. This means different connections
can have different ast/bast pointers, and it reduces the need for the
static pointer.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
We're going to want it in the ast functions, so we convert union
ocfs2_dlm_lksb to struct ocfs2_dlm_lksb and let it carry the connection.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
The stackglue ast and bast functions tried to maintain the fiction that
their arguments were void pointers. In reality, stack_user.c had to
know that the argument was an ocfs2_lock_res in order to get the status
off of the lksb. That's ugly.
This changes stackglue to always pass the lksb as the argument to ast
and bast functions. The caller can always use container_of() to get the
ocfs2_lock_res or user_dlm_lock_res. The net effect to the caller is
zero. They still get back the lockres in their ast. stackglue gets
cleaner, and now can use the lksb itself.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
We're going to remove the tie between ocfs2_dlmfs and o2dlm.
ocfs2_dlmfs doesn't belong in the fs/ocfs2/dlm directory anymore. Here
we move it to fs/ocfs2/dlmfs.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
o2dlm's userspace filesystem is an easy way to use the DLM from
userspace. It is intentionally simple. For example, it does not allow
for asynchronous behavior or lock conversion. This is intentional to
keep the interface simple.
Because there is no asynchronous notification, there is no way for a
process holding a lock to know another node needs the lock. This is the
number one complaint of ocfs2_dlmfs users. Turns out, we can solve this
very easily. We add poll() support to ocfs2_dlmfs. When a BAST is
received, the lock's file descriptor will receive POLLIN.
This is trivial to implement. Userdlm already has an appropriate
waitqueue, and the lock knows when it is blocked.
We add the "bast" capability to tell userspace this is available.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Acked-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Over time, dlmfs has added some features that were not part of the
initial ABI. Unfortunately, some of these features are not detectable
via standard usage. For example, Linux's default poll always returns
POLLIN, so there is no way for a caller of poll(2) to know when dlmfs
added poll support. Instead, we provide this list of new capabilities.
Capabilities is a read-only attribute. We do it as a module parameter
so we can discover it whether dlmfs is built in, loaded, or even not
loaded (via modinfo).
The ABI features are local to this machine's dlmfs mount. This is
distinct from the locking protocol, which is concerned with inter-node
interaction.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
ocfs2 can store extended attribute values as large as a single file. It
does this using a standard ocfs2 btree for the large value. However,
the previous code did not handle all error cases cleanly.
There are multiple problems to have.
1) We have trouble allocating space for a new xattr. This leaves us
with an empty xattr.
2) We overwrote an existing local xattr with a value root, and now we
have an error allocating the storage. This leaves us an empty xattr.
where there used to be a value. The value is lost.
3) We have trouble truncating a reused value. This leaves us with the
original entry pointing to the truncated original value. The value
is lost.
4) We have trouble extending the storage on a reused value. This leaves
us with the original value safely in place, but with more storage
allocated when needed.
This doesn't consider storing local xattrs (values that don't require a
btree). Those only fail when the journal fails.
Case (1) is easy. We just remove the xattr we added. We leak the
storage because we can't safely remove it, but otherwise everything is
happy. We'll print a warning about the leak.
Case (4) is easy. We still have the original value in place. We can
just leave the extra storage attached to this xattr. We return the
error, but the old value is untouched. We print a warning about the
storage.
Case (2) and (3) are hard because we've lost the original values. In
the old code, we ended up with values that could be partially read.
That's not good. Instead, we just wipe the xattr entry and leak the
storage. It stinks that the original value is lost, but now there isn't
a partial value to be read. We'll print a big fat warning.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
