bdev read-only status can be queried using bdev_read_only() and may
change while the device is being opened.  Enforce it by checking it
from blkdev_get() after open succeeds.

This makes bdev_read_only() check in open_bdev_exclusive() and
fsg_lun_open() unnecessary.  Drop them.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: linux-usb@vger.kernel.org

With claim/release rolled into blkdev_get/put(), there's no reason to
keep bd_abort/finish_claim(), __bd_claim() and bd_release() as
separate functions.  It only makes the code difficult to follow.
Collapse them into blkdev_get/put().  This will ease future changes
around claim/release.
Signed-off-by: NTejun Heo <tj@kernel.org>

Over time, block layer has accumulated a set of APIs dealing with bdev
open, close, claim and release.

* blkdev_get/put() are the primary open and close functions.

* bd_claim/release() deal with exclusive open.

* open/close_bdev_exclusive() are combination of open and claim and
  the other way around, respectively.

* bd_link/unlink_disk_holder() to create and remove holder/slave
  symlinks.

* open_by_devnum() wraps bdget() + blkdev_get().

The interface is a bit confusing and the decoupling of open and claim
makes it impossible to properly guarantee exclusive access as
in-kernel open + claim sequence can disturb the existing exclusive
open even before the block layer knows the current open if for another
exclusive access.  Reorganize the interface such that,

* blkdev_get() is extended to include exclusive access management.
  @holder argument is added and, if is @FMODE_EXCL specified, it will
  gain exclusive access atomically w.r.t. other exclusive accesses.

* blkdev_put() is similarly extended.  It now takes @mode argument and
  if @FMODE_EXCL is set, it releases an exclusive access.  Also, when
  the last exclusive claim is released, the holder/slave symlinks are
  removed automatically.

* bd_claim/release() and close_bdev_exclusive() are no longer
  necessary and either made static or removed.

* bd_link_disk_holder() remains the same but bd_unlink_disk_holder()
  is no longer necessary and removed.

* open_bdev_exclusive() becomes a simple wrapper around lookup_bdev()
  and blkdev_get().  It also has an unexpected extra bdev_read_only()
  test which probably should be moved into blkdev_get().

* open_by_devnum() is modified to take @holder argument and pass it to
  blkdev_get().

Most of bdev open/close operations are unified into blkdev_get/put()
and most exclusive accesses are tested atomically at the open time (as
it should).  This cleans up code and removes some, both valid and
invalid, but unnecessary all the same, corner cases.

open_bdev_exclusive() and open_by_devnum() can use further cleanup -
rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop
special features.  Well, let's leave them for another day.

Most conversions are straight-forward.  drbd conversion is a bit more
involved as there was some reordering, but the logic should stay the
same.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NNeil Brown <neilb@suse.de>
Acked-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Acked-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Alex Elder <aelder@sgi.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: dm-devel@redhat.com
Cc: drbd-dev@lists.linbit.com
Cc: Leo Chen <leochen@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Joern Engel <joern@logfs.org>
Cc: reiserfs-devel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>

Code to manage symlinks in /sys/block/*/{holders|slaves} are overly
complex with multiple holder considerations, redundant extra
references to all involved kobjects, unused generic kobject holder
support and unnecessary mixup with bd_claim/release functionalities.

Strip it down to what's necessary (single gendisk holder) and make it
use a separate interface.  This is a step for cleaning up
bd_claim/release.  This patch makes dm-table slightly more complex but
it will be simplified again with further changes.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NNeil Brown <neilb@suse.de>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com

In the failure path of __btrfs_open_devices(), close_bdev_exclusive()
is called with @flags which doesn't match the one used during
open_bdev_exclusive().  Fix it.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Chris Mason <chris.mason@oracle.com>

Andrew Hendry reported a kmemleak warning in 2.6.37-rc1 while editing a
text file with gedit over cifs.

unreferenced object 0xffff88022ee08b40 (size 32):
  comm "gedit", pid 2524, jiffies 4300160388 (age 2633.655s)
  hex dump (first 32 bytes):
    5c 2e 67 6f 75 74 70 75 74 73 74 72 65 61 6d 2d  \.goutputstream-
    35 42 41 53 4c 56 00 de 09 00 00 00 2c 26 78 ee  5BASLV......,&x.
  backtrace:
    [<ffffffff81504a4d>] kmemleak_alloc+0x2d/0x60
    [<ffffffff81136e13>] __kmalloc+0xe3/0x1d0
    [<ffffffffa0313db0>] build_path_from_dentry+0xf0/0x230 [cifs]
    [<ffffffffa031ae1e>] cifs_setattr+0x9e/0x770 [cifs]
    [<ffffffff8115fe90>] notify_change+0x170/0x2e0
    [<ffffffff81145ceb>] sys_fchmod+0x10b/0x140
    [<ffffffff8100c172>] system_call_fastpath+0x16/0x1b
    [<ffffffffffffffff>] 0xffffffffffffffff

The commit 1025774c that removed inode_setattr() seems to have introduced this
memleak by returning early without freeing 'full_path'.
Reported-by: NAndrew Hendry <andrew.hendry@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSuresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Fix openpromfs compilation by adding a missing semicolon in
fs/openpromfs/inode.c openprom_mount().
Signed-off-by: NMeelis Roos <mroos@linux.ee>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 13cfb733 made cifs_ioctl use the tlink attached to the
cifsFileInfo for a filp. This ignores the case of an open directory
however, which in CIFS can have a NULL private_data until a readdir
is done on it.

This patch re-adds the NULL pointer checks that were removed in commit
50ae28f0 and moves the setting of tcon and "caps" variables lower.

Long term, a better fix would be to establish a f_op->open routine for
directories that populates that field at open time, but that requires
some other changes to how readdir calls are handled.
Reported-by: NKjell Rune Skaaraas <kjella79@yahoo.no>
Reviewed-and-Tested-by: NSuresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Add ext4_evict_inode, ext4_drop_inode, ext4_mark_inode_dirty, and
ext4_begin_ordered_truncate()
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Commit 5c521830 (ext4: Support discard requests when running in
no-journal mode) attempts to add sb_issue_discard() for data blocks
(in data=writeback mode) and in no-journal mode.  Unfortunately, this
no longer works, because in commit dd3932ed (block: remove
BLKDEV_IFL_WAIT), sb_issue_discard() only presents a synchronous
interface, and there are times when we call ext4_free_blocks() when we
are are holding a spinlock, or are otherwise in an atomic context.

For now, I've removed the call to sb_issue_discard() to prevent a
deadlock or (if spinlock debugging is enabled) failures like this:

BUG: scheduling while atomic: rc.sysinit/1376/0x00000002
Pid: 1376, comm: rc.sysinit Not tainted 2.6.36-ARCH #1
Call Trace:
[<ffffffff810397ce>] __schedule_bug+0x5e/0x70
[<ffffffff81403110>] schedule+0x950/0xa70
[<ffffffff81060bad>] ? insert_work+0x7d/0x90
[<ffffffff81060fbd>] ? queue_work_on+0x1d/0x30
[<ffffffff81061127>] ? queue_work+0x37/0x60
[<ffffffff8140377d>] schedule_timeout+0x21d/0x360
[<ffffffff812031c3>] ? generic_make_request+0x2c3/0x540
[<ffffffff81402680>] wait_for_common+0xc0/0x150
[<ffffffff81041490>] ? default_wake_function+0x0/0x10
[<ffffffff812034bc>] ? submit_bio+0x7c/0x100
[<ffffffff810680a0>] ? wake_bit_function+0x0/0x40
[<ffffffff814027b8>] wait_for_completion+0x18/0x20
[<ffffffff8120a969>] blkdev_issue_discard+0x1b9/0x210
[<ffffffff811ba03e>] ext4_free_blocks+0x68e/0xb60
[<ffffffff811b1650>] ? __ext4_handle_dirty_metadata+0x110/0x120
[<ffffffff811b098c>] ext4_ext_truncate+0x8cc/0xa70
[<ffffffff810d713e>] ? pagevec_lookup+0x1e/0x30
[<ffffffff81191618>] ext4_truncate+0x178/0x5d0
[<ffffffff810eacbb>] ? unmap_mapping_range+0xab/0x280
[<ffffffff810d8976>] vmtruncate+0x56/0x70
[<ffffffff811925cb>] ext4_setattr+0x14b/0x460
[<ffffffff811319e4>] notify_change+0x194/0x380
[<ffffffff81117f80>] do_truncate+0x60/0x90
[<ffffffff811e08fa>] ? security_inode_permission+0x1a/0x20
[<ffffffff811eaec1>] ? tomoyo_path_truncate+0x11/0x20
[<ffffffff81127539>] do_last+0x5d9/0x770
[<ffffffff811278bd>] do_filp_open+0x1ed/0x680
[<ffffffff8140644f>] ? page_fault+0x1f/0x30
[<ffffffff81132bfc>] ? alloc_fd+0xec/0x140
[<ffffffff81118db1>] do_sys_open+0x61/0x120
[<ffffffff81118e8b>] sys_open+0x1b/0x20
[<ffffffff81002e6b>] system_call_fastpath+0x16/0x1b

https://bugzilla.kernel.org/show_bug.cgi?id=22302Reported-by: NMathias Burén <mathias.buren@gmail.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Cc: jiayingz@google.com

It's not needed to sync the filesystem, and it fixes a lock_dep complaint.
Signed-off-by: NDmitry Monakhov <dmonakhov@gmail.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: NJan Kara <jack@suse.cz>

Use an atomic_t and make sure we don't free the structure while we
might still be submitting I/O for that page.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

The following BUG can occur when an inode which is getting freed when
it still has dirty pages outstanding, and it gets deleted (in this
because it was the target of a rename).  In ordered mode, we need to
make sure the data pages are written just in case we crash before the
rename (or unlink) is committed.  If the inode is being freed then
when we try to igrab the inode, we end up tripping the BUG_ON at
fs/ext4/page-io.c:146.

To solve this problem, we need to keep track of the number of io
callbacks which are pending, and avoid destroying the inode until they
have all been completed.  That way we don't have to bump the inode
count to keep the inode from being destroyed; an approach which
doesn't work because the count could have already been dropped down to
zero before the inode writeback has started (at which point we're not
allowed to bump the count back up to 1, since it's already started
getting freed).

Thanks to Dave Chinner for suggesting this approach, which is also
used by XFS.

  kernel BUG at /scratch_space/linux-2.6/fs/ext4/page-io.c:146!
  Call Trace:
   [<ffffffff811075b1>] ext4_bio_write_page+0x172/0x307
   [<ffffffff811033a7>] mpage_da_submit_io+0x2f9/0x37b
   [<ffffffff811068d7>] mpage_da_map_and_submit+0x2cc/0x2e2
   [<ffffffff811069b3>] mpage_add_bh_to_extent+0xc6/0xd5
   [<ffffffff81106c66>] write_cache_pages_da+0x2a4/0x3ac
   [<ffffffff81107044>] ext4_da_writepages+0x2d6/0x44d
   [<ffffffff81087910>] do_writepages+0x1c/0x25
   [<ffffffff810810a4>] __filemap_fdatawrite_range+0x4b/0x4d
   [<ffffffff810815f5>] filemap_fdatawrite_range+0xe/0x10
   [<ffffffff81122a2e>] jbd2_journal_begin_ordered_truncate+0x7b/0xa2
   [<ffffffff8110615d>] ext4_evict_inode+0x57/0x24c
   [<ffffffff810c14a3>] evict+0x22/0x92
   [<ffffffff810c1a3d>] iput+0x212/0x249
   [<ffffffff810bdf16>] dentry_iput+0xa1/0xb9
   [<ffffffff810bdf6b>] d_kill+0x3d/0x5d
   [<ffffffff810be613>] dput+0x13a/0x147
   [<ffffffff810b990d>] sys_renameat+0x1b5/0x258
   [<ffffffff81145f71>] ? _atomic_dec_and_lock+0x2d/0x4c
   [<ffffffff810b2950>] ? cp_new_stat+0xde/0xea
   [<ffffffff810b29c1>] ? sys_newlstat+0x2d/0x38
   [<ffffffff810b99c6>] sys_rename+0x16/0x18
   [<ffffffff81002a2b>] system_call_fastpath+0x16/0x1b
Reported-by: NNick Bowler <nbowler@elliptictech.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Tested-by: NNick Bowler <nbowler@elliptictech.com>

All the callers already have a pointer to struct cifsInodeInfo. Use it.
Signed-off-by: NSuresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: NPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

This patch is based on Dan's original patch. His original description is
below:

Smatch complained about a couple checking for NULL after dereferencing
bugs.  I'm not super familiar with the code so I did the conservative
thing and move the dereferences after the checks.

The dereferences in cifs_lock() and cifs_fsync() were added in
ba00ba64 "cifs: make various routines use the cifsFileInfo->tcon
pointer".  The dereference in find_writable_file() was added in
6508d904 "cifs: have find_readable/writable_file filter by fsuid".
The comments there say it's possible to trigger the NULL dereference
under stress.
Signed-off-by: NDan Carpenter <error27@gmail.com>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Noticed while reviewing (late) the rbtree conversion patchset (which has been merged
already).

Cc: Jeff Layton <jlayton@redhat.com>
Signed-off-by: NSuresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

We now initialize the percpu counters before replaying the journal,
but after the journal, we recalculate the global counters, to deal
with the possibility of the per-blockgroup counts getting updated by
the journal replay.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: NSteve French <sfrench@us.ibm.com>

Radix trees are ideal when you want to track a bunch of pointers and
can't embed a tracking structure within the target of those pointers.
The tradeoff is an increase in memory, particularly if the tree is
sparse.

In CIFS, we use the tlink_tree to track tcon_link structs. A tcon_link
can never be in more than one tlink_tree, so there's no impediment to
using a rb_tree here instead of a radix tree.

Convert the new multiuser mount code to use a rb_tree instead. This
should reduce the memory required to manage the tlink_tree.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

This is the second version of this patch, the only difference between
it and the first one is that this explicitly makes cifs_sb_master_tlink
a static inline.

Instead of keeping a tag on the master tlink in the tree, just keep a
pointer to the master in the superblock. That eliminates the need for
using the radix tree to look up a tagged entry.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Simplify many places when we need to set oplock level on an inode.
Signed-off-by: NPavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Newer GCC's reported the following build warning:

   fs/ext4/super.c: In function 'ext4_lazyinit_thread':
   fs/ext4/super.c:2702: warning: 'ret' may be used uninitialized in this function

Fix it by removing the need for the ret variable in the first place.
Signed-off-by: N"Lukas Czerner" <lczerner@redhat.com>
Reported-by: N"Stefan Richter" <stefanr@s5r6.in-berlin.de>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

When the request has been removed from the list and no other request
has been issued, we will end up with next wakeup scheduled to
MAX_JIFFY_OFFSET which is bad. So check for that.
Signed-off-by: NLukas Czerner <lczerner@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Linus noted, and complained to me, that doing while lots of "git diff"'s
of kernel sources, these spinlocks were responsible for 27% of the
spinlock cost on his two-processor system as reported by perf.

Git was doing lots of parallel stats, and this was putting a lot of
pressure on ext4_getattr().  A spinlock to protect a single
memory-to-memory copy is pointless, so remove it.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Stanse found that pSMBFile in cifs_ioctl and file->f_path.dentry in
cifs_user_write are dereferenced prior their test to NULL.

The alternative is not to dereference them before the tests. The patch is
to point out the problem, you have to decide.

While at it we cache the inode in cifs_user_write to a local variable
and use all over the function.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: Steve French <sfrench@samba.org>
Cc: linux-cifs@vger.kernel.org
Cc: Jeff Layton <jlayton@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Commit 7d945a3a ("logfs get_sb, part 3") broke the logfs build when
CONFIG_MTD is set due to a mangled logfs_get_sb_mtd() definition.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This one was only used for a nasty hack in nfsd, which has recently
been removed.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The caller allocated it, the caller should free it.

The only issue so far is that we could change the flp pointer even on an
error return if the fl_change callback failed.  But we can simply move
the flp assignment after the fl_change invocation, as the callers don't
care about the flp return value if the setlease call failed.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The NFSv4 server was initializing the dp->dl_flock pointer by the
somewhat ridiculous method of a locks_copy_lock callback.

Now that setlease uses the passed-in lock instead of doing a copy,
dl_flock no longer gets set, resulting in the lock leaking on delegation
release, and later possible hangs (among other problems).

So, initialize dl_flock and get rid of the callback.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We modified setlease to require the caller to allocate the new lease in
the case of creating a new lease, but forgot to fix up the filesystem
methods.

Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Steve French <sfrench@samba.org>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We're depending on setlease to free the passed-in lease on failure.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Removing a lock shouldn't require any allocations; a failure due to
ENOMEM leaves the caller with a choice between retrying or giving up and
leaking an unused lease.

Next we should split the other lease calls into add and delete cases.
I wanted to start with just the bugfix.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

    In fanotify_read() return -ERESTARTSYS instead of -EINTR to
    make read() restartable across signals (BSD semantic).
Signed-off-by: NEric Paris <eparis@redhat.com>

The btrfs merge looks like hell, because it changes fs-writeback.c, and
the crazy code has this repeated "estimate number of dirty pages"
counting that involves three different helper functions.  And it's done
in two different places.

Just unify that whole calculation as a "get_nr_dirty_pages()" helper
function, and the merge result will look half-way decent.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The definition of PAGE_CACHE_MASK in <linux/pagemap.h> is needed to use
MAX_RW_COUNT, and on x86-64 that gets done indirectly through the
architecture header includes.  But on MIPS and s390 that doesn't happen,
and we need to make sure that fs/compat.c includes pagemap.h explicitly.

Introduced in commit 435f49a5 ("readv/writev: do the same
MAX_RW_COUNT truncation that read/write does").

Reported-by: Sachin Sant <sachinp@in.ibm.com> (S390)
Reported-by: wu zhangjin <wuzhangjin@gmail.com> (MIPS)
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

During unlink we remove any references to the inode from
the tree log.  It can return -ENOENT and other errors,
and this changes the unlink code to deal with it.
Signed-off-by: NChris Mason <chris.mason@oracle.com>

jbd2_slab_create_sem is used as a mutex, so make it one.

[ akpm muttered: We may as well make it local to
jbd2_journal_create_slab() also. ]
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <alpine.LFD.2.00.1010162231480.2496@localhost6.localdomain6>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

sbi->hpfs_creation_de is used as mutex so make it a mutex.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NChristoph Hellwig <hch@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
LKML-Reference: <20100907125056.228874895@linutronix.de>

Add a mount option user_subvol_rm_allowed that allows users to delete a
(potentially non-empty!) subvol when they would otherwise we allowed to do
an rmdir(2).  We duplicate the may_delete() checks from the core VFS code
to implement identical security checks (minus the directory size check).
We additionally require that the user has write+exec permission on the
subvol root inode.
Signed-off-by: NSage Weil <sage@newdream.net>
Signed-off-by: NChris Mason <chris.mason@oracle.com>