Recently, one of our colleagues meet with a problem that if we
write/delete a 32mb files repeatly, we will get an ENOSPC in
the end. And the corresponding bug is 1288.
http://oss.oracle.com/bugzilla/show_bug.cgi?id=1288
The real problem is that although we have freed the clusters,
they are in truncate log and they will be summed up so that
we can free them once in a whole.
So this patch just try to resolve it. In case we see -ENOSPC
in ocfs2_write_begin_no_lock, we will check whether the truncate
log has enough clusters for our need, if yes, we will try to
flush the truncate log at that point and try again. This method
is inspired by Mark Fasheh <mfasheh@suse.com>. Thanks.
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Commit 1c66b360fe (Change some lock status member in ocfs2_lock_res
to char.) states that these fields need to be signed due to comparision
to -1, but only changed the type from unsigned char to char. However, it
is a compiler option if char is a signed or unsigned type. Change these
fields to signed char so the code will work with all compilers.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Commit 83fd9c7 changes l_level, l_requested and l_blocking of
ocfs2_lock_res from int to unsigned char. But actually it is
initially as -1(ocfs2_lock_res_init_common) which
correspoding to 255 for unsigned char. So the whole dlm lock
mechanism doesn't work now which means a disaster to ocfs2.
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Currently, the default behavior of O_DIRECT writes was allowing
concurrent writing among nodes to the same file, with no cluster
coherency guaranteed (no EX lock held). This can leave stale data in
the cache for buffered reads on other nodes.
The new mount option introduce a chance to choose two different
behaviors for O_DIRECT writes:
* coherency=full, as the default value, will disallow
concurrent O_DIRECT writes by taking
EX locks.
* coherency=buffered, allow concurrent O_DIRECT writes
without EX lock among nodes, which
gains high performance at risk of
getting stale data on other nodes.
Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Adds support for heartbeat=global mount option. It ensures that the heartbeat
mode passed matches the one enabled on disk.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
OCFS2_FEATURE_INCOMPAT_CLUSTERINFO allows us to use sb->s_cluster_info for
both userspace and o2cb cluster stacks. It also allows us to extend cluster
info to include stack flags.
This patch also adds stackflags to sb->s_clusterinfo. It also introduces a
clusterinfo flag OCFS2_CLUSTER_O2CB_GLOBAL_HEARTBEAT to denote the enabled
global heartbeat mode.
This incompat flag can be set/cleared using tunefs.ocfs2 --fs-features. The
clusterinfo flag is set/cleared using tunefs.ocfs2 --update-cluster-stack.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Durring orphan scan, if we are slot 0, and we are replaying
orphan_dir:0001, the general process is that for every file
in this dir:
1. we will iget orphan_dir:0001, since there is no inode for it.
we will have to create an inode and read it from the disk.
2. do the normal work, such as delete_inode and remove it from
the dir if it is allowed.
3. call iput orphan_dir:0001 when we are done. In this case,
since we have no dcache for this inode, i_count will
reach 0, and VFS will have to call clear_inode and in
ocfs2_clear_inode we will checkpoint the inode which will let
ocfs2_cmt and journald begin to work.
4. We loop back to 1 for the next file.
So you see, actually for every deleted file, we have to read the
orphan dir from the disk and checkpoint the journal. It is very
time consuming and cause a lot of journal checkpoint I/O.
A better solution is that we can have another reference for these
inodes in ocfs2_super. So if there is no other race among
nodes(which will let dlmglue to checkpoint the inode), for step 3,
clear_inode won't be called and for step 1, we may only need to
read the inode for the 1st time. This is a big win for us.
So this patch will try to cache system inodes of other slots so
that we will have one more reference for these inodes and avoid
the extra inode read and journal checkpoint.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Thanks for the comments. I have incorportated them all.
CONFIG_OCFS2_FS_STATS is enabled and CONFIG_DEBUG_LOCK_ALLOC is disabled.
Statistics now look like -
ocfs2_write_ctxt: 2144 - 2136 = 8
ocfs2_inode_info: 1960 - 1848 = 112
ocfs2_journal: 168 - 160 = 8
ocfs2_lock_res: 336 - 304 = 32
ocfs2_refcount_tree: 512 - 472 = 40
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.de>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
The fixes include:
1. some endian problems.
2. we should use bit/bpc in ocfs2_block_group_grow_discontig to
allocate clusters.
3. set num_clusters properly in __ocfs2_claim_clusters.
4. change name from ocfs2_supports_discontig_bh to
ocfs2_supports_discontig_bg.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
If we cannot get a contiguous region for a block group, allocate a
discontiguous one when the filesystem supports it.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Tao Ma <tao.ma@oracle.com>
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>
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>
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>
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>
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>
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>
This patch add extent block (metadata) stealing mechanism for
extent allocation. This mechanism is same as the inode stealing.
if no room in slot specific extent_alloc, we will try to
allocate extent block from the next slot.
Signed-off-by: Tiger Yang <tiger.yang@oracle.com>
Acked-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
There is possibility of a livelock in __ocfs2_cluster_lock(). If a node were
to get an ast for an upconvert request, followed immediately by a bast,
there is a small window where the fs may downconvert the lock before the
process requesting the upconvert is able to take the lock.
This patch adds a new flag to indicate that the upconvert is still in
progress and that the dc thread should not downconvert it right now.
Wengang Wang <wen.gang.wang@oracle.com> and Joel Becker
<joel.becker@oracle.com> contributed heavily to this patch.
Reported-by: David Teigland <teigland@redhat.com>
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2:
ocfs2/trivial: Use le16_to_cpu for a disk value in xattr.c
ocfs2/trivial: Use proper mask for 2 places in hearbeat.c
Ocfs2: Let ocfs2 support fiemap for symlink and fast symlink.
Ocfs2: Should ocfs2 support fiemap for S_IFDIR inode?
ocfs2: Use FIEMAP_EXTENT_SHARED
fiemap: Add new extent flag FIEMAP_EXTENT_SHARED
ocfs2: replace u8 by __u8 in ocfs2_fs.h
ocfs2: explicit declare uninitialized var in user_cluster_connect()
ocfs2-devel: remove redundant OCFS2_MOUNT_POSIX_ACL check in ocfs2_get_acl_nolock()
ocfs2: return -EAGAIN instead of EAGAIN in dlm
ocfs2/cluster: Make fence method configurable - v2
ocfs2: Set MS_POSIXACL on remount
ocfs2: Make acl use the default
ocfs2: Always include ACL support
Mainline commit 53ef99cad9 removed the
JBD compatibility layer from OCFS2. This patch removes the last remaining
remnants of that.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Change acl mount options handling to match the one of XFS and BTRFS and
hopefully it is also easier to use now. When admin does not specify any
acl mount option, acls are enabled if and only if the filesystem has
xattr feature enabled. If admin specifies 'acl' mount option, we fail
the mount if the filesystem does not have xattr feature and thus acls
cannot be enabled.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Implement locking around struct ocfs2_refcount_tree. This protects
all read/write operations on refcount trees. ocfs2_refcount_tree
has its own lock and its own caching_info, protecting buffers among
multiple nodes.
User must call ocfs2_lock_refcount_tree before his operation on
the tree and unlock it after that.
ocfs2_refcount_trees are referenced by the block number of the
refcount tree root block, So we create an rb-tree on the ocfs2_super
to look them up.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
The next step in divorcing metadata I/O management from struct inode is
to pass struct ocfs2_caching_info to the journal functions. Thus the
journal locks a metadata cache with the cache io_lock function. It also
can compare ci_last_trans and ci_created_trans directly.
This is a large patch because of all the places we change
ocfs2_journal_access..(handle, inode, ...) to
ocfs2_journal_access..(handle, INODE_CACHE(inode), ...).
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Similar ip_last_trans, ip_created_trans tracks the creation of a journal
managed inode. This specifically tracks what transaction created the
inode. This is so the code can know if the inode has ever been written
to disk.
This behavior is desirable for any journal managed object. We move it
to struct ocfs2_caching_info as ci_created_trans so that any object
using ocfs2_caching_info can rely on this behavior.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
We have the read side of metadata caching isolated to struct
ocfs2_caching_info, now we need the write side. This means the journal
functions. The journal only does a couple of things with struct inode.
This change moves the ip_last_trans field onto struct
ocfs2_caching_info as ci_last_trans. This field tells the journal
whether a pending journal flush is required.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
We don't really want to cart around too many new fields on the
ocfs2_caching_info structure. So let's wrap all our access of the
parent object in a set of operations. One pointer on caching_info, and
more flexibility to boot.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
We want to use the ocfs2_caching_info structure in places that are not
inodes. To do that, it can no longer rely on referencing the inode
directly.
This patch moves the flags to ocfs2_caching_info->ci_flags, stores
pointers to the parent's locks on the ocfs2_caching_info, and renames
the constants and flags to reflect its independant state.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
In commit ea455f8ab6, we moved the dentry lock
put process into ocfs2_wq. This causes problems during umount because ocfs2_wq
can drop references to inodes while they are being invalidated by
invalidate_inodes() causing all sorts of nasty things (invalidate_inodes()
ending in an infinite loop, "Busy inodes after umount" messages etc.).
We fix the problem by stopping ocfs2_wq from doing any further releasing of
inode references on the superblock being unmounted, wait until it finishes
the current round of releasing and finally cleaning up all the references in
dentry_lock_list from ocfs2_put_super().
The issue was tracked down by Tao Ma <tao.ma@oracle.com>.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Add lockdep support to OCFS2. The support also covers all of the cluster
locks except for open locks, journal locks, and local quotafile locks. These
are special because they are acquired for a node, not for a particular process
and lockdep cannot deal with such type of locking.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Currently if the orphan scan fires a tick before the user issues the umount,
the umount will wait for the queued orphan scan tasks to complete.
This patch makes the umount stop the orphan scan as early as possible so as
to reduce the probability of the queued tasks slowing down the umount.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
It would be nice to know how often we get checksum failures. Even
better, how many of them we can fix with the single bit ecc. So, we add
a statistics structure. The structure can be installed into debugfs
wherever the user wants.
For ocfs2, we'll put it in the superblock-specific debugfs directory and
pass it down from our higher-level functions. The stats are only
registered with debugfs when the filesystem supports metadata ecc.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
When a dentry is unlinked, the unlinking node takes an EX on the dentry lock
before moving the dentry to the orphan directory. Other nodes that have
this dentry in cache have a PR on the same dentry lock. When the EX is
requested, the other nodes flag the corresponding inode as MAYBE_ORPHANED
during downconvert. The inode is finally deleted when the last node to iput
the inode sees that i_nlink==0 and the MAYBE_ORPHANED flag is set.
A problem arises if a node is forced to free dentry locks because of memory
pressure. If this happens, the node will no longer get downconvert
notifications for the dentries that have been unlinked on another node.
If it also happens that node is actively using the corresponding inode and
happens to be the one performing the last iput on that inode, it will fail
to delete the inode as it will not have the MAYBE_ORPHANED flag set.
This patch fixes this shortcoming by introducing a periodic scan of the
orphan directories to delete such inodes. Care has been taken to distribute
the workload across the cluster so that no one node has to perform the task
all the time.
Signed-off-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
During recovery, a node recovers orphans in it's slot and the dead node(s). But
if the dead nodes were holding orphans in offline slots, they will be left
unrecovered.
If the dead node is the last one to die and is holding orphans in other slots
and is the first one to mount, then it only recovers it's own slot, which
leaves orphans in offline slots.
This patch queues complete_recovery to clean orphans for all offline slots
during mount and node recovery.
Signed-off-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Acked-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
For nfs exporting, ocfs2_get_dentry() returns the dentry for fh.
ocfs2_get_dentry() may read from disk when the inode is not in memory,
without any cross cluster lock. this leads to the file system loading a
stale inode.
This patch fixes above problem.
Solution is that in case of inode is not in memory, we get the cluster
lock(PR) of alloc inode where the inode in question is allocated from (this
causes node on which deletion is done sync the alloc inode) before reading
out the inode itsself. then we check the bitmap in the group (the inode in
question allcated from) to see if the bit is clear. if it's clear then it's
stale. if the bit is set, we then check generation as the existing code
does.
We have to read out the inode in question from disk first to know its alloc
slot and allot bit. And if its not stale we read it out using ocfs2_iget().
The second read should then be from cache.
And also we have to add a per superblock nfs_sync_lock to cover the lock for
alloc inode and that for inode in question. this is because ocfs2_get_dentry()
and ocfs2_delete_inode() lock on them in reverse order. nfs_sync_lock is locked
in EX mode in ocfs2_get_dentry() and in PR mode in ocfs2_delete_inode(). so
that mutliple ocfs2_delete_inode() can run concurrently in normal case.
[mfasheh@suse.com: build warning fixes and comment cleanups]
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Acked-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
In ocfs2, the block group search looks for the "emptiest" group
to allocate from. So if the allocator has many equally(or almost
equally) empty groups, new block group will tend to get spread
out amongst them.
So we add osb_inode_alloc_group in ocfs2_super to record the last
used inode allocation group.
For more details, please see
http://oss.oracle.com/osswiki/OCFS2/DesignDocs/InodeAllocationStrategy.
I have done some basic test and the results are a ten times improvement on
some cold-cache stat workloads.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
ocfs2_dx_dir_rebalance() is passed the block offset of a dx leaf which needs
rebalancing. Since we rebalance an entire cluster at a time however, this
function needs to calculate the beginning of that cluster, in blocks. The
calculation was wrong, which would result in a read of non-leaf blocks. Fix
the calculation by adding ocfs2_block_to_cluster_start() which is a more
straight-forward way of determining this.
Reported-by: Tristan Ye <tristan.ye@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Since we've now got a directory format capable of handling a large number of
entries, we can increase the maximum link count supported. This only gets
increased if the directory indexing feature is turned on.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Acked-by: Joel Becker <joel.becker@oracle.com>
This patch makes use of Ocfs2's flexible btree code to add an additional
tree to directory inodes. The new tree stores an array of small,
fixed-length records in each leaf block. Each record stores a hash value,
and pointer to a block in the traditional (unindexed) directory tree where a
dirent with the given name hash resides. Lookup exclusively uses this tree
to find dirents, thus providing us with constant time name lookups.
Some of the hashing code was copied from ext3. Unfortunately, it has lots of
unfixed checkpatch errors. I left that as-is so that tracking changes would
be easier.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Acked-by: Joel Becker <joel.becker@oracle.com>
This patch removes the debugfs file local_alloc_stats as that information
is now included in the fs_state debugfs file.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
This patch creates a per mount debugfs file, fs_state, which exposes
information like, cluster stack in use, states of the downconvert, recovery
and commit threads, number of journal txns, some allocation stats, list of
all slots, etc.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
For other metadata in ocfs2, metaecc is checked in ocfs2_read_blocks
with io_mutex held. While for xattr bucket, it is calculated by
the whole buckets. So we have to add a spin_lock to prevent multiple
processes calculating metaecc.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Tested-by: Tristan Ye <tristan.ye@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Dropping of last reference to dentry lock is a complicated operation involving
dropping of reference to inode. This can get complicated and quota code in
particular needs to obtain some quota locks which leads to potential deadlock.
Thus we defer dropping of inode reference to ocfs2_wq.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Future ocfs2 features metaecc and indexed directories need to store a
little bit of data in each dirblock. For compatibility, we place this
in a trailer at the end of the dirblock. The trailer plays itself as an
empty dirent, so that if the features are turned off, it can be reused
without requiring a tunefs scan.
This code adds the trailer and validates it when the block is read in.
[ Mark is the original author, but I reinserted this code before his
dir index work. -- Joel ]
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
The per-metadata-type ocfs2_journal_access_*() functions hook up jbd2
commit triggers and allow us to compute metadata ecc right before the
buffers are written out. This commit provides ecc for inodes, extent
blocks, group descriptors, and quota blocks. It is not safe to use
extened attributes and metaecc at the same time yet.
The ocfs2_extent_tree and ocfs2_path abstractions in alloc.c both hide
the type of block at their root. Before, it didn't matter, but now the
root block must use the appropriate ocfs2_journal_access_*() function.
To keep this abstract, the structures now have a pointer to the matching
journal_access function and a wrapper call to call it.
A few places use naked ocfs2_write_block() calls instead of adding the
blocks to the journal. We make sure to calculate their checksum and ecc
before the write.
Since we pass around the journal_access functions. Let's typedef them
in ocfs2.h.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
This is the code that computes crc32 and ecc for ocfs2 metadata blocks.
There are high-level functions that check whether the filesystem has the
ecc feature, mid-level functions that work on a single block or array of
buffer_heads, and the low-level ecc hamming code that can handle
multiple buffers like crc32_le().
It's not hooked up to the filesystem yet.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
