This problem was found when running 'tests/tst-zfs-mount.so' multiple times.
At the first time, all tests succeed, however, a subsequent run would
fail at the test: 'mkdir /foo/bar', the error message reported
that the target file already exists.

The test basically creates a directory /foo/bar, rename it to /foo/bar2,
then remove /foo/bar2. How could /foo/bar still be there?

Quite simple. Our shutdown function calls unmount_rootfs() which will
attempt to unmount zfs with the flag MNT_FOURCE, however, it's not being
passed to zfs_unmount(), neither unmount_rootfs() tests itself the
return status (which was always getting failures previously).
So OSv is really being shutdown while there is remaining data waiting to
be synced with the backing store. As a result, inconsitency.

This problem was fixed by passing the flag to VFS_UNMOUNT which will now
unmount the fs properly on sudden shutdowns.

Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Currently, vflush is used in the unmount process to release remaining
dentries. vflush in turn calls vevict that is releasing dentries that
it doesn't own.
This behavior is not correct neither good to the future of VFS.

So Avi suggested switching to a different approach. We could only
release those dentries owned by the mountpoint when unmounting it as
there wouldn't be anything else in the dcache (given its functionality).

The problem was fixed by doing the following steps:
 - Drop vflush calls in sys_umount2, make vevict an empty function,
and remove vevict.

 - Created the function release_mp_dentries to release dentries of a mount
point which will be called by VFS_UNMOUNT. It cannot be called before
VFS_UNMOUNT as failures must be considered, neither after as the mount point
would be considered busy.
Don't respect this "rule", and that previously seen ZFS replay transaction
error would happen.

NOTE: vflush is currently duplicated in zfs unmount cases to address the problem
above. This patch fixes this duplication as well.

Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Currently, namei() does vget() unconditionally if no dentry is found.
This is wrong because the path can be a hard link that points to a vnode
that's already in memory.

To fix the problem:

  - Use inode number as part of the hash in vget()

  - Use vn_lookup() in vget() to make sure we have one vnode in memory
    per inode number.

  - Push the vget() calls down to individual filesystems and make
    VOP_LOOKUP return an vnode

Changes since v2:
  - v1 dropped lock in vn_lookup, thus assert that vnode_lock is held.

Changes since v3:
  - Fix lock ordering issue in dentry_lookup. The lock respective to the parent
node must be acquired before dentry_lookup and released after the process is
done. Otherwise, a second thread looking up for the same dentry may take the
'NULL' path incorrectly.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

This reverts commit e4aad1ba.

It causes tst-vfs.so to just hang.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Currently, namei() does vget() unconditionally if no dentry is found.
This is wrong because the path can be a hard link that points to a vnode
that's already in memory.

To fix the problem:

  - Use inode number as part of the hash in vget()

  - Use vn_lookup() in vget() to make sure we have one vnode in memory
    per inode number.

  - Push the vget() calls down to individual filesystems and make
    VOP_LOOKUP return an vnode

  - Drop lock in vn_lookup() and assert that vnode_lock is held.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

Signed-off-by: Asias He <asias@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Use vop_eperm instead to warn the caller about the lack of support (Glauber Costa).

Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Tested-by: Tomasz Grabiec <tgrabiec@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

vop_eperm allows more code reuse (suggested by Glauber Costa)

Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Needed by pivot_root() to unmount the initial rootfs.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

This happens when you move a file to a different directory.

Thread 2 (Thread 2):
 1  0x000000000032ed3b in halt_no_interrupts ()
   at ../../arch/x64/processor.hh:239
   osv::halt () at ../../core/power.cc:28
 2  0x000000000020e7fe in abort (
    msg=msg@entry=0x580160 "page fault outside application")
    at ../../runtime.cc:109
 3  0x00000000002ecfdc in page_fault (ef=0xffffc0003e362008)
    at ../../core/mmu.cc:981
 4  <signal handler called>
 5  merge (b=0xffffc0003b4e8000, a=0xfffffffffffffff8)
    at ../../core/mempool.cc:421
 6  memory::free_page_range_locked (range=range@entry=0xffffc0003b4e8000)
    at ../../core/mempool.cc:436
 7  0x00000000003186d7 in memory::free_page_range (
    range=range@entry=0xffffc0003b4e8000) at ../../core/mempool.cc:448
 8  0x0000000000319280 in free_large (obj=0xffffc0003b4e9000)
    at ../../core/mempool.cc:460
 9  std_free (object=0xffffc0003b4e9000) at ../../core/mempool.cc:790
 10 free (obj=0xffffc0003b4e9000) at ../../core/mempool.cc:892
 11 0x0000000000340e52 in ramfs_free_node (np=np@entry=0xffffc0003d250d40)
    at ../../fs/ramfs/ramfs_vnops.c:78
 12 0x0000000000340ed2 in ramfs_remove_node (dnp=0xffffc0003d250a00,
    np=0xffffc0003d250d40) at ../../fs/ramfs/ramfs_vnops.c:131
 13 0x0000000000340ffd in ramfs_rename (dvp1=0xffffc0003fc9a180,
    vp1=0xffffc0003fc9a100, name1=<optimized out>, dvp2=0xffffc0003fc9a280,
    vp2=<optimized out>, name2=0x2000001fedf1 "prefix_suffix")
    at ../../fs/ramfs/ramfs_vnops.c:380
 14 0x0000000000340069 in sys_rename (src=<optimized out>,
    dest=<optimized out>) at ../../fs/vfs/vfs_syscalls.c:671
 15 0x000000000033a3b2 in rename (oldpath=<optimized out>,
    newpath=0xffffc0003e858cc0 "/tmp/t3-26e1b47c/prefix_suffix")
    at ../../fs/vfs/main.cc:634

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>

strlcpy() expects buffer length not string length.

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>

Wire up the VOP_LINK vnode operation for ramfs in preparation for
sys_link().

Signed-off-by: Raphael S. Carvalho <raphael.scarv@gmail.com>
[ penberg: split to separate commit ]
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Use ->rn_namelen as the destination buffer size for strlcpy().

Spotted by Coverity.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

The ramfs_remove_node() will free vp->v_data so we cannot look it up in
ramfs_remove().

Spotted by Coverity.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Create a new dentry structure for pathname components, following the Linux
VFS model.  The vnodes are left-as is for now but are always fronted by
dentries for pathname lookups.  In a second step they will be moved to
use non-pathname indices.

[penberg: fix open(O_CREAT|O_EXCL) breakage ]

I've also added an osv/ prefix to make sure we don't clash with system headers.

We probably should either adopt this globally or drop it, but I fear we'll run into
problems with the latter approach.

This will allow for easy addition of the vectored and positional I/O
syscalls, as well as making the structure of the I/O path more similar
to *BSD and Solaris.