We missed using the variable length string macros in several
tracepoints. Fixed them in this change.
There's probably more useful macros that we can use to print
others like flags etc. But I'll submit sepawrate patches for
those at a future date.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Cc: <stable@vger.kernel.org> # v5.12
Signed-off-by: Steve French <stfrench@microsoft.com>
SMB3.0 doesn't have encryption negotiate context but simply uses
the SMB2_GLOBAL_CAP_ENCRYPTION flag.
When that flag is present in the neg response cifs.ko uses AES-128-CCM
which is the only cipher available in this context.
cipher_type was set to the server cipher only when parsing encryption
negotiate context (SMB3.1.1).
For SMB3.0 it was set to 0. This means cipher_type value can be 0 or 1
for AES-128-CCM.
Fix this by checking for SMB3.0 and encryption capability and setting
cipher_type appropriately.
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
When smb2 lease parameter is disabled on server. Server grants
batch oplock instead of RHW lease by default on open, inode page cache
needs to be zapped immediatley upon close as cache is not valid.
Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Removed oplock_break_received flag which was added to achieve
synchronization between oplock handler and open handler by earlier commit.
It is not needed because there is an existing lock open_file_lock to achieve
the same. find_readable_file takes open_file_lock and then traverses the
openFileList. Similarly, cifs_oplock_break while closing the deferred
handle (i.e cifsFileInfo_put) takes open_file_lock and then sends close
to the server.
Added comments for better readability.
Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
When using smb2_copychunk_range() for large ranges we will
run through several iterations of a loop calling SMB2_ioctl()
but never actually free the returned buffer except for the final
iteration.
This leads to memory leaks everytime a large copychunk is requested.
Fixes: 9bf0c9cd43 ("CIFS: Fix SMB2/SMB3 Copy offload support (refcopy) for large files")
Cc: <stable@vger.kernel.org>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
See MS-SMB2 3.2.4.1.4, file ids in compounded requests should be set to
0xFFFFFFFFFFFFFFFF (we were treating it as u32 not u64 and setting
it incorrectly).
Signed-off-by: Steve French <stfrench@microsoft.com>
Reported-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Deadstore detected by Lukas Bulwahn's CodeChecker Tool (ELISA group).
line 741 struct cifsInodeInfo *cinode;
line 747 cinode = CIFS_I(d_inode(cfile->dentry));
could be deleted.
cinode on filesystem should not be deleted when files are closed,
they are representations of some data fields on a physical disk,
thus no further action is required.
The virtual inode on vfs will be handled by vfs automatically,
and the denotation is inode, which is different from the cinode.
Signed-off-by: wenhuizhang <wenhui@gwmail.gwu.edu>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Mounting with "multichannel" is obviously implied if user requested
more than one channel on mount (ie mount parm max_channels>1).
Currently both have to be specified. Fix that so that if max_channels
is greater than 1 on mount, enable multichannel rather than silently
falling back to non-multichannel.
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-By: Tom Talpey <tom@talpey.com>
Cc: <stable@vger.kernel.org> # v5.11+
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
We were ignoring CAP_MULTI_CHANNEL in the server response - if the
server doesn't support multichannel we should not be attempting it.
See MS-SMB2 section 3.2.5.2
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-By: Tom Talpey <tom@talpey.com>
Cc: <stable@vger.kernel.org> # v5.8+
Signed-off-by: Steve French <stfrench@microsoft.com>
In the SMB3/SMB3.1.1 negotiate protocol request, we are supposed to
advertise CAP_MULTICHANNEL capability when establishing multiple
channels has been requested by the user doing the mount. See MS-SMB2
sections 2.2.3 and 3.2.5.2
Without setting it there is some risk that multichannel could fail
if the server interpreted the field strictly.
Reviewed-By: Tom Talpey <tom@talpey.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Cc: <stable@vger.kernel.org> # v5.8+
Signed-off-by: Steve French <stfrench@microsoft.com>
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Merge tag '5.13-rc-smb3-part2' of git://git.samba.org/sfrench/cifs-2.6
Pull cifs updates from Steve French:
"Ten CIFS/SMB3 changes - including two marked for stable - including
some important multichannel fixes, as well as support for handle
leases (deferred close) and shutdown support:
- some important multichannel fixes
- support for handle leases (deferred close)
- shutdown support (which is also helpful since it enables multiple
xfstests)
- enable negotiating stronger encryption by default (GCM256)
- improve wireshark debugging by allowing more options for root to
dump decryption keys
SambaXP and the SMB3 Plugfest test event are going on now so I am
expecting more patches over the next few days due to extra testing
(including more multichannel fixes)"
* tag '5.13-rc-smb3-part2' of git://git.samba.org/sfrench/cifs-2.6:
fs/cifs: Fix resource leak
Cifs: Fix kernel oops caused by deferred close for files.
cifs: fix regression when mounting shares with prefix paths
cifs: use echo_interval even when connection not ready.
cifs: detect dead connections only when echoes are enabled.
smb3.1.1: allow dumping keys for multiuser mounts
smb3.1.1: allow dumping GCM256 keys to improve debugging of encrypted shares
cifs: add shutdown support
cifs: Deferred close for files
smb3.1.1: enable negotiating stronger encryption by default
The -EIO error return path is leaking memory allocated
to page. Fix this by moving the allocation block after
the check of cifs_forced_shutdown.
Addresses-Coverity: ("Resource leak")
Fixes: 087f757b01 ("cifs: add shutdown support")
Signed-off-by: Khaled ROMDHANI <khaledromdhani216@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Fix regression issue caused by deferred close for files.
Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
The commit 315db9a05b ("cifs: fix leak in cifs_smb3_do_mount() ctx")
revealed an existing bug when mounting shares that contain a prefix
path or DFS links.
cifs_setup_volume_info() requires the @devname to contain the full
path (UNC + prefix) to update the fs context with the new UNC and
prepath values, however we were passing only the UNC
path (old_ctx->UNC) in @device thus discarding any prefix paths.
Instead of concatenating both old_ctx->{UNC,prepath} and pass it in
@devname, just keep the dup'ed values of UNC and prepath in
cifs_sb->ctx after calling smb3_fs_context_dup(), and fix
smb3_parse_devname() to correctly parse and not leak the new UNC and
prefix paths.
Cc: <stable@vger.kernel.org> # v5.11+
Fixes: 315db9a05b ("cifs: fix leak in cifs_smb3_do_mount() ctx")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Acked-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>
When the tcp connection is not ready to send requests,
we keep retrying echo with an interval of zero.
This seems unnecessary, and this fix changes the interval
between echoes to what is specified as echo_interval.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
We can detect server unresponsiveness only if echoes are enabled.
Echoes can be disabled under two scenarios:
1. The connection is low on credits, so we've disabled echoes/oplocks.
2. The connection has not seen any request till now (other than
negotiate/sess-setup), which is when we enable these two, based on
the credits available.
So this fix will check for dead connection, only when echo is enabled.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
CC: <stable@vger.kernel.org> # v5.8+
Signed-off-by: Steve French <stfrench@microsoft.com>
When mounted multiuser it is hard to dump keys for the other sessions
which makes it hard to debug using network traces (e.g. using wireshark).
Suggested-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Previously we were only able to dump CCM or GCM-128 keys (see "smbinfo keys" e.g.)
to allow network debugging (e.g. wireshark) of mounts to SMB3.1.1 encrypted
shares. But with the addition of GCM-256 support, we have to be able to dump
32 byte instead of 16 byte keys which requires adding an additional ioctl
for that.
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Various filesystem support the shutdown ioctl which is used by various
xfstests. The shutdown ioctl sets a flag on the superblock which
prevents open, unlink, symlink, hardlink, rmdir, create etc.
on the file system until unmount and remounted. The two flags supported
in this patch are:
FSOP_GOING_FLAGS_LOGFLUSH and FSOP_GOING_FLAGS_NOLOGFLUSH
which require very little other than blocking new operations (since
we do not cache writes to metadata on the client with cifs.ko).
FSOP_GOING_FLAGS_DEFAULT is not supported yet, but could be added in
the future but would need to call syncfs or equivalent to write out
pending data on the mount.
With this patch various xfstests now work including tests 043 through
046 for example.
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
When file is closed, SMB2 close request is not sent to server
immediately and is deferred for acregmax defined interval. When file is
reopened by same process for read or write, the file handle
is reused if an oplock is held.
When client receives a oplock/lease break, file is closed immediately
if reference count is zero, else oplock is downgraded.
Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Now that stronger encryption (gcm256) has been more broadly
tested, and confirmed to work with multiple servers (Windows
and Azure for example), enable it by default. Although gcm256 is
the second choice we offer (after gcm128 which should be faster),
this change allows mounts to server which are configured to
require the strongest encryption to work (without changing a module
load parameter).
Signed-off-by: Steve French <stfrench@microsoft.com>
Suggested-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Pull vfs inode type handling updates from Al Viro:
"We should never change the type bits of ->i_mode or the method tables
(->i_op and ->i_fop) of a live inode.
Unfortunately, not all filesystems took care to prevent that"
* 'work.inode-type-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
spufs: fix bogosity in S_ISGID handling
9p: missing chunk of "fs/9p: Don't update file type when updating file attributes"
openpromfs: don't do unlock_new_inode() until the new inode is set up
hostfs_mknod(): don't bother with init_special_inode()
cifs: have cifs_fattr_to_inode() refuse to change type on live inode
cifs: have ->mkdir() handle race with another client sanely
do_cifs_create(): don't set ->i_mode of something we had not created
gfs2: be careful with inode refresh
ocfs2_inode_lock_update(): make sure we don't change the type bits of i_mode
orangefs_inode_is_stale(): i_mode type bits do *not* form a bitmap...
vboxsf: don't allow to change the inode type
afs: Fix updating of i_mode due to 3rd party change
ceph: don't allow type or device number to change on non-I_NEW inodes
ceph: fix up error handling with snapdirs
new helper: inode_wrong_type()
In some cases readahead of more than the read size can help
(to allow parallel i/o of read ahead which can improve performance).
Ceph introduced a mount parameter "rasize" to allow controlling this.
Add mount parameter "rasize" to allow control of amount of readahead
requested of the server. If rasize not set, rasize defaults to
negotiated rsize as before.
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
For servers which don't support copy_range (SMB3 CopyChunk), the
logging of:
CIFS: VFS: \\server\share refcpy ioctl error -95 getting resume key
can fill the client logs and make debugging real problems more
difficult. Change the -EOPNOTSUPP on copy_range to a "warn once"
Signed-off-by: Steve French <stfrench@microsoft.com>
pfid is being set to tcon->crfid.fid and they are copied in each other
multiple times. Remove the memcopy between same pointers - memory
locations.
Addresses-Coverity: ("Overlapped copy")
Fixes: 9e81e8ff74 ("cifs: return cached_fid from open_shroot")
Signed-off-by: Muhammad Usama Anjum <musamaanjum@gmail.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
If smb3_notify() is called at mount point of CIFS, build_path_from_dentry()
returns the pointer to kmalloc-ed memory with terminating zero (this is
empty FileName to be passed to SMB2 CREATE request). This pointer is assigned
to the `path` variable.
Then `path + 1` (to skip first backslash symbol) is passed to
cifs_convert_path_to_utf16(). This is incorrect for empty path and causes
out-of-bound memory access.
Get rid of this "increase by one". cifs_convert_path_to_utf16() already
contains the check for leading backslash in the path.
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=212693
CC: <stable@vger.kernel.org> # v5.6+
Signed-off-by: Eugene Korenevsky <ekorenevsky@astralinux.ru>
Signed-off-by: Steve French <stfrench@microsoft.com>
* rqst[1,2,3] is allocated in vars
* each rqst->rq_iov is also allocated in vars or using pooled memory
SMB2_open_free, SMB2_ioctl_free, SMB2_query_info_free are iterating on
each rqst after vars has been freed (use-after-free), and they are
freeing the kvec a second time (double-free).
How to trigger:
* compile with KASAN
* mount a share
$ smbinfo quota /mnt/foo
Segmentation fault
$ dmesg
==================================================================
BUG: KASAN: use-after-free in SMB2_open_free+0x1c/0xa0
Read of size 8 at addr ffff888007b10c00 by task python3/1200
CPU: 2 PID: 1200 Comm: python3 Not tainted 5.12.0-rc6+ #107
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014
Call Trace:
dump_stack+0x93/0xc2
print_address_description.constprop.0+0x18/0x130
? SMB2_open_free+0x1c/0xa0
? SMB2_open_free+0x1c/0xa0
kasan_report.cold+0x7f/0x111
? smb2_ioctl_query_info+0x240/0x990
? SMB2_open_free+0x1c/0xa0
SMB2_open_free+0x1c/0xa0
smb2_ioctl_query_info+0x2bf/0x990
? smb2_query_reparse_tag+0x600/0x600
? cifs_mapchar+0x250/0x250
? rcu_read_lock_sched_held+0x3f/0x70
? cifs_strndup_to_utf16+0x12c/0x1c0
? rwlock_bug.part.0+0x60/0x60
? rcu_read_lock_sched_held+0x3f/0x70
? cifs_convert_path_to_utf16+0xf8/0x140
? smb2_check_message+0x6f0/0x6f0
cifs_ioctl+0xf18/0x16b0
? smb2_query_reparse_tag+0x600/0x600
? cifs_readdir+0x1800/0x1800
? selinux_bprm_creds_for_exec+0x4d0/0x4d0
? do_user_addr_fault+0x30b/0x950
? __x64_sys_openat+0xce/0x140
__x64_sys_ioctl+0xb9/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fdcf1f4ba87
Code: b3 66 90 48 8b 05 11 14 2c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 13 2c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffef1ce7748 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000c018cf07 RCX: 00007fdcf1f4ba87
RDX: 0000564c467c5590 RSI: 00000000c018cf07 RDI: 0000000000000003
RBP: 00007ffef1ce7770 R08: 00007ffef1ce7420 R09: 00007fdcf0e0562b
R10: 0000000000000100 R11: 0000000000000246 R12: 0000000000004018
R13: 0000000000000001 R14: 0000000000000003 R15: 0000564c467c5590
Allocated by task 1200:
kasan_save_stack+0x1b/0x40
__kasan_kmalloc+0x7a/0x90
smb2_ioctl_query_info+0x10e/0x990
cifs_ioctl+0xf18/0x16b0
__x64_sys_ioctl+0xb9/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xae
Freed by task 1200:
kasan_save_stack+0x1b/0x40
kasan_set_track+0x1c/0x30
kasan_set_free_info+0x20/0x30
__kasan_slab_free+0xe5/0x110
slab_free_freelist_hook+0x53/0x130
kfree+0xcc/0x320
smb2_ioctl_query_info+0x2ad/0x990
cifs_ioctl+0xf18/0x16b0
__x64_sys_ioctl+0xb9/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xae
The buggy address belongs to the object at ffff888007b10c00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
512-byte region [ffff888007b10c00, ffff888007b10e00)
The buggy address belongs to the page:
page:0000000044e14b75 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b10
head:0000000044e14b75 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x100000000010200(slab|head)
raw: 0100000000010200 ffffea000015f500 0000000400000004 ffff888001042c80
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888007b10b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888007b10b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888007b10c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888007b10c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888007b10d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Can aid in making mount problems easier to diagnose
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This makes the errors accessible from userspace via dmesg and
the fs_context fd.
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Add fs_context param to parsing helpers to be able to log into it in
next patch.
Make some helper static as they are not used outside of fs_context.c
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This new helper will be used in the fs_context mount option parsing
code. It log errors both in:
* the fs_context log queue for userspace to read
* kernel printk buffer (dmesg, old behaviour)
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Emulated via server side copy and setsize for
SMB3 and later. In the future we could compound
this (and/or optionally use DUPLICATE_EXTENTS
if supported by the server).
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Emulated for SMB3 and later via server side copy
and setsize. Eventually this could be compounded.
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Needed for the final patch in the directory caching series
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
and clear the timestamp when we receive a lease break.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Needed for subsequent patches in the directory caching
series.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
We need to hold both a reference for the root/superblock as well as the directory that we
are caching. We need to drop these references before we call kill_anon_sb().
At this point, the root and the cached dentries are always the same but this will change
once we start caching other directories as well.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
And use this to only allow to take out a shared handle once the mount has completed and the
sb becomes available.
This will become important in follow up patches where we will start holding a reference to the
directory dentry for the shared handle during the lifetime of the handle.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
These functions will eventually be used to cache any directory, not just the root
so change the names.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Move the check for the directory path into the open_shroot() function
but still fail for any non-root directories.
This is preparation for later when we will start using the cache also
for other directories than the root.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
instead of doing it in the callsites for open_shroot.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
The cost is that we might need to flip '/' to '\\' in more than
just the prefix. Needs profiling, but I suspect that we won't
get slowdown on that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steve French <stfrench@microsoft.com>
build_path_from_dentry() open-codes dentry_path_raw(). The reason
we can't use dentry_path_raw() in there (and postprocess the
result as needed) is that the callers of build_path_from_dentry()
expect that the object to be freed on cleanup and the string to
be used are at the same address. That's painful, since the path
is naturally built end-to-beginning - we start at the leaf and
go through the ancestors, accumulating the pathname.
Life would be easier if we left the buffer allocation to callers.
It wouldn't be exact-sized buffer, but none of the callers keep
the result for long - it's always freed before the caller returns.
So there's no need to do exact-sized allocation; better use
__getname()/__putname(), same as we do for pathname arguments
of syscalls. What's more, there's no need to do allocation under
spinlocks, so GFP_ATOMIC is not needed.
Next patch will replace the open-coded dentry_path_raw() (in
build_path_from_dentry_optional_prefix()) with calling the real
thing. This patch only introduces wrappers for allocating/freeing
the buffers and switches to new calling conventions:
build_path_from_dentry(dentry, buf)
expects buf to be address of a page-sized object or NULL,
return value is a pathname built inside that buffer on success,
ERR_PTR(-ENOMEM) if buf is NULL and ERR_PTR(-ENAMETOOLONG) if
the pathname won't fit into page. Note that we don't need to
check for failure when allocating the buffer in the caller -
build_path_from_dentry() will do the right thing.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steve French <stfrench@microsoft.com>
Aurelien Aptel