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2009-12-09Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (42 commits) tree-wide: fix misspelling of "definition" in comments reiserfs: fix misspelling of "journaled" doc: Fix a typo in slub.txt. inotify: remove superfluous return code check hdlc: spelling fix in find_pvc() comment doc: fix regulator docs cut-and-pasteism mtd: Fix comment in Kconfig doc: Fix IRQ chip docs tree-wide: fix assorted typos all over the place drivers/ata/libata-sff.c: comment spelling fixes fix typos/grammos in Documentation/edac.txt sysctl: add missing comments fs/debugfs/inode.c: fix comment typos sgivwfb: Make use of ARRAY_SIZE. sky2: fix sky2_link_down copy/paste comment error tree-wide: fix typos "couter" -> "counter" tree-wide: fix typos "offest" -> "offset" fix kerneldoc for set_irq_msi() spidev: fix double "of of" in comment comment typo fix: sybsystem -> subsystem ...
2009-12-08Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6Linus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1815 commits) mac80211: fix reorder buffer release iwmc3200wifi: Enable wimax core through module parameter iwmc3200wifi: Add wifi-wimax coexistence mode as a module parameter iwmc3200wifi: Coex table command does not expect a response iwmc3200wifi: Update wiwi priority table iwlwifi: driver version track kernel version iwlwifi: indicate uCode type when fail dump error/event log iwl3945: remove duplicated event logging code b43: fix two warnings ipw2100: fix rebooting hang with driver loaded cfg80211: indent regulatory messages with spaces iwmc3200wifi: fix NULL pointer dereference in pmkid update mac80211: Fix TX status reporting for injected data frames ath9k: enable 2GHz band only if the device supports it airo: Fix integer overflow warning rt2x00: Fix padding bug on L2PAD devices. WE: Fix set events not propagated b43legacy: avoid PPC fault during resume b43: avoid PPC fault during resume tcp: fix a timewait refcnt race ... Fix up conflicts due to sysctl cleanups (dead sysctl_check code and CTL_UNNUMBERED removed) in kernel/sysctl_check.c net/ipv4/sysctl_net_ipv4.c net/ipv6/addrconf.c net/sctp/sysctl.c
2009-12-08Merge git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl-2.6Linus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl-2.6: (43 commits) security/tomoyo: Remove now unnecessary handling of security_sysctl. security/tomoyo: Add a special case to handle accesses through the internal proc mount. sysctl: Drop & in front of every proc_handler. sysctl: Remove CTL_NONE and CTL_UNNUMBERED sysctl: kill dead ctl_handler definitions. sysctl: Remove the last of the generic binary sysctl support sysctl net: Remove unused binary sysctl code sysctl security/tomoyo: Don't look at ctl_name sysctl arm: Remove binary sysctl support sysctl x86: Remove dead binary sysctl support sysctl sh: Remove dead binary sysctl support sysctl powerpc: Remove dead binary sysctl support sysctl ia64: Remove dead binary sysctl support sysctl s390: Remove dead sysctl binary support sysctl frv: Remove dead binary sysctl support sysctl mips/lasat: Remove dead binary sysctl support sysctl drivers: Remove dead binary sysctl support sysctl crypto: Remove dead binary sysctl support sysctl security/keys: Remove dead binary sysctl support sysctl kernel: Remove binary sysctl logic ...
2009-12-07Merge branch 'for-next' into for-linusJiri Kosina
Conflicts: kernel/irq/chip.c
2009-12-04tree-wide: fix assorted typos all over the placeAndré Goddard Rosa
That is "success", "unknown", "through", "performance", "[re|un]mapping" , "access", "default", "reasonable", "[con]currently", "temperature" , "channel", "[un]used", "application", "example","hierarchy", "therefore" , "[over|under]flow", "contiguous", "threshold", "enough" and others. Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-12-04tree-wide: fix typos "offest" -> "offset"Uwe Kleine-König
This patch was generated by git grep -E -i -l 'offest' | xargs -r perl -p -i -e 's/offest/offset/' Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-12-01Merge branch 'master' of ↵David S. Miller
master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 Conflicts: net/mac80211/ht.c
2009-11-18sysctl: Drop & in front of every proc_handler.Eric W. Biederman
For consistency drop & in front of every proc_handler. Explicity taking the address is unnecessary and it prevents optimizations like stubbing the proc_handlers to NULL. Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Joe Perches <joe@perches.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2009-11-13ocfs2: Trivial cleanup of jbd compatibility layer removalSunil Mushran
Mainline commit 53ef99cad9878f02f27bb30bc304fc42af8bdd6e 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>
2009-11-12sysctl fs: Remove dead binary sysctl supportEric W. Biederman
Now that sys_sysctl is a generic wrapper around /proc/sys .ctl_name and .strategy members of sysctl tables are dead code. Remove them. Cc: Jan Harkes <jaharkes@cs.cmu.edu> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2009-10-29ocfs2: return f_fsid info in ocfs2_statfs()Coly Li
Currently the f_fsid of struct kstatfs returned from ocfs2_statfs() is undefined (vfs layer fills in 0 as default). Since in some conditions, f_fsid value might be used in a (f_fsid, ino) pair to uniquely identify a file, ocfs2 should return a unique defined f_fsid value from ocfs2_statfs(). Because uuid_str is the same on big or litlle endian machine, it's endian consistent to use osb->uuid_str to generate f_fsid value. Signed-off-by: Coly Li <coly.li@suse.de> Cc: Sunil Mushran <sunil.mushran@oracle.com> Cc: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
2009-10-28ocfs2: duplicate inline data properly during reflink.Tao Ma
The old reflink fails to handle inodes with inline data and will oops if it encounters them. This patch copies inline data to the new inode. Extended attributes may still be refcounted. Signed-off-by: Tao Ma <tao.ma@oracle.com> Signed-off-by: Joel Becker <joel.becker@oracle.com> Tested-by: Tristan Ye <tristan.ye@oracle.com>
2009-10-28ocfs2: Move ocfs2_complete_reflink to the right place.Tao Ma
As its name ocfs2_complete_reflink indicates, it should be called after all the work for reflink is done, so it really should be called after we reflink xattr successfully. Signed-off-by: Tao Ma <tao.ma@oracle.com> Signed-off-by: Joel Becker <joel.becker@oracle.com> Tested-by: Tristan Ye <tristan.ye@oracle.com>
2009-10-28ocfs2: Return -EINVAL when a device is not ocfs2.Joel Becker
In case of non-modular kernels the root filesystem is mounted by trying several filesystems. If ocfs2 was tried before the actual filesystem type, the mount would fail because ocfs2_sb_probe() returns -EAGAIN instead of -EINVAL. ocfs2 will now return -EINVAL properly. Signed-off-by: Joel Becker <joel.becker@oracle.com> Reported-by: Laszlo Attila Toth <panther@balabit.hu>
2009-10-18inet: rename some inet_sock fieldsEric Dumazet
In order to have better cache layouts of struct sock (separate zones for rx/tx paths), we need this preliminary patch. Goal is to transfert fields used at lookup time in the first read-mostly cache line (inside struct sock_common) and move sk_refcnt to a separate cache line (only written by rx path) This patch adds inet_ prefix to daddr, rcv_saddr, dport, num, saddr, sport and id fields. This allows a future patch to define these fields as macros, like sk_refcnt, without name clashes. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-10-01const: constify remaining file_operationsAlexey Dobriyan
[akpm@linux-foundation.org: fix KVM] Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Acked-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-27const: mark struct vm_struct_operationsAlexey Dobriyan
* mark struct vm_area_struct::vm_ops as const * mark vm_ops in AGP code But leave TTM code alone, something is fishy there with global vm_ops being used. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-24Merge branch 'hwpoison' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 * 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6: (21 commits) HWPOISON: Enable error_remove_page on btrfs HWPOISON: Add simple debugfs interface to inject hwpoison on arbitary PFNs HWPOISON: Add madvise() based injector for hardware poisoned pages v4 HWPOISON: Enable error_remove_page for NFS HWPOISON: Enable .remove_error_page for migration aware file systems HWPOISON: The high level memory error handler in the VM v7 HWPOISON: Add PR_MCE_KILL prctl to control early kill behaviour per process HWPOISON: shmem: call set_page_dirty() with locked page HWPOISON: Define a new error_remove_page address space op for async truncation HWPOISON: Add invalidate_inode_page HWPOISON: Refactor truncate to allow direct truncating of page v2 HWPOISON: check and isolate corrupted free pages v2 HWPOISON: Handle hardware poisoned pages in try_to_unmap HWPOISON: Use bitmask/action code for try_to_unmap behaviour HWPOISON: x86: Add VM_FAULT_HWPOISON handling to x86 page fault handler v2 HWPOISON: Add poison check to page fault handling HWPOISON: Add basic support for poisoned pages in fault handler v3 HWPOISON: Add new SIGBUS error codes for hardware poison signals HWPOISON: Add support for poison swap entries v2 HWPOISON: Export some rmap vma locking to outside world ...
2009-09-23headers: utsname.h reduxAlexey Dobriyan
* remove asm/atomic.h inclusion from linux/utsname.h -- not needed after kref conversion * remove linux/utsname.h inclusion from files which do not need it NOTE: it looks like fs/binfmt_elf.c do not need utsname.h, however due to some personality stuff it _is_ needed -- cowardly leave ELF-related headers and files alone. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-23Merge branch 'upstream-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2 * 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2: (85 commits) ocfs2: Use buffer IO if we are appending a file. ocfs2: add spinlock protection when dealing with lockres->purge. dlmglue.c: add missed mlog lines ocfs2: __ocfs2_abort() should not enable panic for local mounts ocfs2: Add ioctl for reflink. ocfs2: Enable refcount tree support. ocfs2: Implement ocfs2_reflink. ocfs2: Add preserve to reflink. ocfs2: Create reflinked file in orphan dir. ocfs2: Use proper parameter for some inode operation. ocfs2: Make transaction extend more efficient. ocfs2: Don't merge in 1st refcount ops of reflink. ocfs2: Modify removing xattr process for refcount. ocfs2: Add reflink support for xattr. ocfs2: Create an xattr indexed block if needed. ocfs2: Call refcount tree remove process properly. ocfs2: Attach xattr clusters to refcount tree. ocfs2: Abstract ocfs2 xattr tree extend rec iteration process. ocfs2: Abstract the creation of xattr block. ocfs2: Remove inode from ocfs2_xattr_bucket_get_name_value. ...
2009-09-23seq_file: constify seq_operationsJames Morris
Make all seq_operations structs const, to help mitigate against revectoring user-triggerable function pointers. This is derived from the grsecurity patch, although generated from scratch because it's simpler than extracting the changes from there. Signed-off-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-23ocfs2: Use buffer IO if we are appending a file.Tao Ma
In ocfs2_file_aio_write, we will prevent direct io if we find that we are appending(changing i_size) and call generic_file_aio_write_nolock. But actually O_DIRECT flag is there and this function will call generic_file_direct_write eventually which will update i_size and leave di->i_size alone. The bug is http://oss.oracle.com/bugzilla/show_bug.cgi?id=1173. So this patch let ocfs2_direct_IO returns 0 directly if we are appending so that buffered write will be called and di->i_size get updated successfully. And this is also what we want in ocfs2_file_aio_write. Signed-off-by: Tao Ma <tao.ma@oracle.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
2009-09-23ocfs2: add spinlock protection when dealing with lockres->purge.Wengang Wang
when we check/modify lockres->purge, we should with the protection of lockres->spinlock. in dlm_purge_lockres(), the checking/modifying is not with the protectin. this patch fixes it. Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
2009-09-23dlmglue.c: add missed mlog linesColy Li
This patch adds the missed mlog_exit() and mlog_exit_void() lines when routines return. Signed-off-by: Coly Li <coly.li@suse.de> Acked-by: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
2009-09-23ocfs2: __ocfs2_abort() should not enable panic for local mountsSunil Mushran
In a clustered setup, we have to panic the box on journal abort. This is because we don't have the facility to go hard readonly. With hard ro, another node would detect node failure and initiate recovery. Having said that, we shouldn't force panic if the volume is mounted locally. This patch defers the handling to the mount option, errors. Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
2009-09-22ocfs2: Add ioctl for reflink.Tao Ma
The ioctl will take 3 parameters: old_path, new_path and preserve and call vfs_reflink. It is useful when we backport reflink features to old kernels. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Enable refcount tree support.Tao Ma
Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Implement ocfs2_reflink.Tao Ma
Implement ocfs2_reflink. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Add preserve to reflink.Tao Ma
reflink has 2 options for the destination file: 1. snapshot: reflink will attempt to preserve ownership, permissions, and all other security state in order to create a full snapshot. 2. new file: it will acquire the data extent sharing but will see the file's security state and attributes initialized as a new file. So add the option to ocfs2. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Create reflinked file in orphan dir.Tao Ma
reflink is a very complicated process, so it can't be integrated into one transaction. So if the system panic in the operation, we may leave a unfinished inode in the destication directory. So we will try to create an inode in orphan_dir first, reflink it to the src file and then move it to the destication file in the end. In that way we won't be afraid of any corruption during the reflink. This patch adds 2 functions for orphan_dir operation: 1. Create a new inode in orphand dir. 2. Move an inode to a target dir. Note: fsck.ocfs2 should work for us to remove the unfinished file in the orphan_dir. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Use proper parameter for some inode operation.Tao Ma
In order to make the original function more suitable for reflink, we modify the following inode operations. Both are tiny. 1. ocfs2_mknod_locked only use dentry for mlog, so move it to the caller so that reflink can use it without dentry. 2. ocfs2_prepare_orphan_dir only want inode to get its ip_blkno. So use ip_blkno instead. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Make transaction extend more efficient.Tao Ma
In ocfs2_extend_rotate_transaction, op_credits is the orignal credits in the handle and we only want to extend the credits for the rotation, but the old solution always double it. It is harmless for some minor operations, but for actions like reflink we may rotate tree many times and cause the credits increase dramatically. So this patch try to only increase the desired credits. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Don't merge in 1st refcount ops of reflink.Tao Ma
Actually the whole reflink will touch refcount tree 2 times: 1. It will add the clusters in the extent record to the tree if it isn't refcounted before. 2. It will add 1 refcount to these clusters when it add these extent records to the tree. So actually we shouldn't do merge in the 1st operation since the 2nd one will soon be called and we may have to split it again. Do a merge first and split soon is a waste of time. So we only merge in the 2nd round. This is done by adding a new internal __ocfs2_increase_refcount and call it with "not-merge" for 1st refcount operation in reflink. This also has a side-effect that we don't need to worry too much about the metadata allocation in the 2nd round since it will only merge and no split will happen for those records. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Modify removing xattr process for refcount.Tao Ma
The old xattr value remove is quite simple, it just erase the tree and free the clusters. But as we have added refcount support, The process is a little complicated. We have to lock the refcount tree at the beginning, what's more, we may split the refcount tree in some cases, so meta/credits are needed. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Add reflink support for xattr.Tao Ma
Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Create an xattr indexed block if needed.Tao Ma
With reflink, there is a need that we create a new xattr indexed block from the very beginning. So add a new parameter for ocfs2_create_xattr_block. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Call refcount tree remove process properly.Tao Ma
Now with xattr refcount support, we need to check whether we have xattr refcounted before we remove the refcount tree. Now the mechanism is: 1) Check whether i_clusters == 0, if no, exit. 2) check whether we have i_xattr_loc in dinode. if yes, exit. 2) Check whether we have inline xattr stored outside, if yes, exit. 4) Remove the tree. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Attach xattr clusters to refcount tree.Tao Ma
In ocfs2, when xattr's value is larger than OCFS2_XATTR_INLINE_SIZE, it will be kept outside of the blocks we store xattr entry. And they are stored in a b-tree also. So this patch try to attach all these clusters to refcount tree also. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Abstract ocfs2 xattr tree extend rec iteration process.Tao Ma
Currently we have ocfs2_iterate_xattr_buckets which can receive a para and a callback to iterate a series of bucket. It is good. But actually the 2 callers ocfs2_xattr_tree_list_index_block and ocfs2_delete_xattr_index_block are almost the same. The only difference is that the latter need to handle the extent record also. So add a new function named ocfs2_iterate_xattr_index_block. It can be given func callback which are used for exten record. So now we only have one iteration function for the xattr index block. Ane what's more, it is useful for our future reflink operations. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Abstract the creation of xattr block.Tao Ma
In xattr reflink, we also need to create xattr block, so abstract the process out. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Remove inode from ocfs2_xattr_bucket_get_name_value.Tao Ma
In ocfs2_xattr_bucket_get_name_value, actually we only use super_block. So use it. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Add CoW support for xattr.Tao Ma
In order to make 2 transcation(xattr and cow) independent with each other, we CoW the whole xattr out in case we are setting them. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Abstract duplicate clusters process in CoW.Tao Ma
We currently use pagecache to duplicate clusters in CoW, but it isn't suitable for xattr case. So abstract it out so that the caller can decide which method it use. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Return extent flags for xattr value tree.Tao Ma
With the new refcount tree, xattr value can also be refcounted among multiple files. So return the appropriate extent flags so that CoW can used it later. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: handle file attributes issue for reflink.Tao Ma
A reflink creates a snapshot of a file, that means the attributes must be identical except for three exceptions - nlink, ino, and ctime. As for time changes, Here is a brief description: 1. Source file: 1) atime: Ignore. Let the lazy atime code handle that. 2) mtime: don't touch. 3) ctime: If we change the tree (adding REFCOUNTED to at least one extent), update it. 2. Destination file: 1) atime: ignore. 2) mtime: we want it to appear identical to the source. 3) ctime: update. The idea here is that an ls -l will show the same time for the src and target - it shows mtime. Backup software like rsync and tar will treat the new file correctly too. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Add normal functions for reflink a normal file's extents.Tao Ma
2 major functions are added in this patch. ocfs2_attach_refcount_tree will create a new refcount tree to the old file if it doesn't have one and insert all the extent records to the tree if they are not refcounted. ocfs2_create_reflink_node will: 1. set the refcount tree to the new file. 2. call ocfs2_duplicate_extent_list which will iterate all the extents for the old file, insert it to the new file and increase the corresponding referennce count. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: CoW a reflinked cluster when it is truncated.Tao Ma
When we truncate a file to a specific size which resides in a reflinked cluster, we need to CoW it since ocfs2_zero_range_for_truncate will zero the space after the size(just another type of write). So we add a "max_cpos" in ocfs2_refcount_cow so that it will stop when it hit the max cluster offset. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Integrate CoW in file write.Tao Ma
When we use mmap, we CoW the refcountd clusters in ocfs2_write_begin_nolock. While for normal file io(including directio), we do CoW in ocfs2_prepare_inode_for_write. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: CoW refcount tree improvement.Tao Ma
During CoW, if the old extent record is refcounted, we allocate som new clusters and do CoW. Actually we can have some improvement here. If the old extent has refcount=1, that means now it is only used by this file. So we don't need to allocate new clusters, just remove the refcounted flag and it is OK. We also have to remove it from the refcount tree while not deleting it. Signed-off-by: Tao Ma <tao.ma@oracle.com>
2009-09-22ocfs2: Add CoW support.Tao Ma
This patch try CoW support for a refcounted record. the whole process will be: 1. Calculate how many clusters we need to CoW and where we start. Extents that are not completely encompassed by the write will be broken on 1MB boundaries. 2. Do CoW for the clusters with the help of page cache. 3. Change the b-tree structure with the new allocated clusters. Signed-off-by: Tao Ma <tao.ma@oracle.com>