This is aimed at preventing stacked filesystems like nullfs and unionfs
from "losing" their lower mounts due to forced unmount. Otherwise,
VFS operations that are passed through to the lower filesystem(s) may
crash or otherwise cause unpredictable behavior.
Introduce two new functions: vfs_pin_from_vp() and vfs_unpin().
which are intended to be called on the lower mount(s) when the stacked
filesystem is mounted and unmounted, respectively.
Much as registration in the mnt_uppers list previously did, pinning
will prevent even forced unmount of the lower FS and will allow the
stacked FS to freely operate on the lower mount either by direct
use of the struct mount* or indirect use through a properly-referenced
vnode's v_mount field.
vfs_pin_from_vp() is modeled after vfs_ref_from_vp() in that it uses
the mount interlock coupled with re-checking vp->v_mount to ensure
that it will fail in the face of a pending unmount request, even if
the concurrent unmount fully completes.
Adopt these new functions in both nullfs and unionfs.
Reviewed By: kib, markj
Differential Revision: https://reviews.freebsd.org/D30401
- VFS_UNMOUNT() requires vn_start_write() around it [*].
- call VFS_PURGE() before unmount.
- do not destroy mp if cleanup unmount did not succeed.
- set MNTK_UNMOUNT, and indicate forced unmount with MNTK_UNMOUNTF
for VFS_UNMOUNT() in cleanup.
PR: 251320 [*]
Reported by: Tong Zhang <ztong0001@gmail.com>
Reviewed by: markj, mjg
Discussed with: rmacklem
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D27327
This ensures that no writes are pending in memory, either metadata or
user data, but not including dirty pages not yet converted to fs writes.
Only filesystems declared local are suspended.
Note that this does not guarantee absence of the metadata errors or
leaks if resume is not done: for instance, on UFS unlinked but opened
inodes are leaked and require fsck to gc.
Reviewed by: markj
Discussed with: imp
Tested by: imp (previous version), pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D27054
The 2 provided zones had inconsistent naming between each other
("int" and "64") and other allocator zones (which use bytes).
Follow malloc by naming them "pcpu-" + size in bytes.
This is a step towards replacing ad-hoc per-cpu zones with
general slabs.
r363210 introduced v_seqc_users to the vnodes. This change requires
a vn_seqc_write_end() to match the vn_seqc_write_begin() in
vfs_cache_root_clear().
mjg@ provided this patch which seems to fix the panic.
Tested for an NFS mount where the VFS_STATFS() call will fail.
Submitted by: mjg
Reviewed by: mjg
Differential Revision: https://reviews.freebsd.org/D26160
with vnode locked, use NOWAIT alloc and only report when we don't overflow.
These changes were accidentally omitted from r364402, except for the not
reporting on overflow. They were lumped in with a debugging commit in my tree
that I omitted w/o realizing this.
Other issues from the review are pending some other changes I need to do first.
Report when a filesystem is mounted, remounted or unmounted via devd, along with
details about the mount point and mount options.
Discussed with: kib@
Reviewed by: kirk@ (prior version)
Sponsored by: Netflix
Diffential Revision: https://reviews.freebsd.org/D25969
Modified on each permission change and link/unlink.
Reviewed by: kib
Tested by: pho (in a patchset)
Differential Revision: https://reviews.freebsd.org/D25573
There may be some version of mountd out there that does not supply a default
security flavor when none is given for an export.
Set the default security flavor in vfs_export if none is given, and remove the
workaround for oexport compat.
Reported by: npn
Reviewed by: rmacklem
Approved by: mav (mentor)
MFC after: 3 days
Sponsored by: iXsystems, Inc.
Differential Revision: https://reviews.freebsd.org/D25300
Since mnt_flags was upgraded to 64bits there has been a quirk in
"struct export_args", since it hold a copy of mnt_flags
in ex_flags, which is an "int" (32bits).
This happens to currently work, since all the flag bits used in ex_flags are
defined in the low order 32bits. However, new export flags cannot be defined.
Also, ex_anon is a "struct xucred", which limits it to 16 additional groups.
This patch revises "struct export_args" to make ex_flags 64bits and replaces
ex_anon with ex_uid, ex_ngroups and ex_groups (which points to a
groups list, so it can be malloc'd up to NGROUPS in size.
This requires that the VFS_CHECKEXP() arguments change, so I also modified the
last "secflavors" argument to be an array pointer, so that the
secflavors could be copied in VFS_CHECKEXP() while the export entry is locked.
(Without this patch VFS_CHECKEXP() returns a pointer to the secflavors
array and then it is used after being unlocked, which is potentially
a problem if the exports entry is changed.
In practice this does not occur when mountd is run with "-S",
but I think it is worth fixing.)
This patch also deleted the vfs_oexport_conv() function, since
do_mount_update() does the conversion, as required by the old vfs_cmount()
calls.
Reviewed by: kib, freqlabs
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D25088
vfs_export requires security flavors be explicitly listed when
exporting as of r360900.
Use the default AUTH_SYS flavor when converting old export args to
ensure compatibility with the legacy mount syscall.
Reported by: rmacklem
Reviewed by: rmacklem
Approved by: mav (mentor)
MFC after: 3 days
Sponsored by: iXsystems, Inc.
Differential Revision: https://reviews.freebsd.org/D25045
r353150 added mnt_rootvnode and this seems to have broken NFS mounts when the
VFS_STATFS() called just after VFS_MOUNT() returns an error.
Then the code calls VFS_UNMOUNT(), which calls vflush(), which returns EBUSY.
Then the thread get stuck sleeping on "mntref" in vfs_mount_destroy().
This patch fixes this problem.
Reviewed by: kib, mjg
Differential Revision: https://reviews.freebsd.org/D24022
In particular on amd64 this eliminates an atomic op in the common case,
trading it for IPIs in the uncommon case of catching CPUs executing the
code while the filesystem is getting suspended or unmounted.
mount point while numerous tests are running that are writing to
files on that mount point cause the unmount(8) to hang forever.
The unmount(8) system call is handled in the kernel by the dounmount()
function. The cause of the hang is that prior to dounmount() calling
VFS_UNMOUNT() it is calling VFS_SYNC(mp, MNT_WAIT). The MNT_WAIT
flag indicates that VFS_SYNC() should not return until all the dirty
buffers associated with the mount point have been written to disk.
Because user processes are allowed to continue writing and can do
so faster than the data can be written to disk, the call to VFS_SYNC()
can never finish.
Unlike VFS_SYNC(), the VFS_UNMOUNT() routine can suspend all processes
when they request to do a write thus having a finite number of dirty
buffers to write that cannot be expanded. There is no need to call
VFS_SYNC() before calling VFS_UNMOUNT(), because VFS_UNMOUNT() needs
to flush everything again anyway after suspending writes, to catch
anything that was dirtied between the VFS_SYNC() and writes being
suspended.
The fix is to simply remove the unnecessary call to VFS_SYNC() from
dounmount().
Reported by: Peter Holm
Analysis by: Chuck Silvers
Tested by: Peter Holm
MFC after: 7 days
Sponsored by: Netflix
The current notion of an active vnode is eliminated.
Vnodes transition between 0<->1 hold counts all the time and the
associated traversal between different lists induces significant
scalability problems in certain workloads.
Introduce a global list containing all allocated vnodes. They get
unlinked only when UMA reclaims memory and are only requeued when
hold count reaches 0.
Sample result from an incremental make -s -j 104 bzImage on tmpfs:
stock: 118.55s user 3649.73s system 7479% cpu 50.382 total
patched: 122.38s user 1780.45s system 6242% cpu 30.480 total
Reviewed by: jeff
Tested by: pho (in a larger patch, previous version)
Differential Revision: https://reviews.freebsd.org/D22997
This obviates the need to scan the entire active list looking for vnodes
of interest.
msync is handled by adding all vnodes with write count to the lazy list.
deferred inactive directly adds vnodes as it sets the VI_DEFINACT flag.
Vnodes get dequeued from the list when their hold count reaches 0.
Newly added MNT_VNODE_FOREACH_LAZY* macros support filtering so that
spurious locking is avoided in the common case.
Reviewed by: jeff
Tested by: pho (in a larger patch, previous version)
Differential Revision: https://reviews.freebsd.org/D22995
The previous behavior of leaving VI_OWEINACT vnodes on the active list without
a hold count is eliminated. Hold count is kept and inactive processing gets
explicitly deferred by setting the VI_DEFINACT flag. The syncer is then
responsible for vdrop.
Reviewed by: kib (previous version)
Tested by: pho (in a larger patch, previous version)
Differential Revision: https://reviews.freebsd.org/D23036
Filesystems which want to use it in limited capacity can employ the
VOP_UNLOCK_FLAGS macro.
Reviewed by: kib (previous version)
Differential Revision: https://reviews.freebsd.org/D21427
Root vnodes looekd up all the time, e.g. when crossing a mount point.
Currently used routines always perform a costly lookup which can be
trivially avoided.
Reviewed by: jeff (previous version), kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21646
When a VFS option passed to nmount is present but NULL the kernel will
place an empty option in its internal list. This will have a NULL
pointer and a length of 0. When we come to read one of these the kernel
will try to load from the last address of virtual memory. This is
normally invalid so will fault resulting in a kernel panic.
Fix this by checking if the length is valid before dereferencing.
MFC after: 3 days
Sponsored by: DARPA, AFRL
The two options are
* nocover/cover: Prevent/allow mounting over an existing root mountpoint.
E.g., "mount -t ufs -o nocover /dev/sd1a /usr/local" will fail if /usr/local
is already a mountpoint.
* emptydir/noemptydir: Prevent/allow mounting on a non-empty directory.
E.g., "mount -t ufs -o emptydir /dev/sd1a /usr" will fail.
Neither of these options is intended to be a default, for historical and
compatibility reasons.
Reviewed by: allanjude, kib
Differential Revision: https://reviews.freebsd.org/D21458
There are 3 counters modified all the time in this structure - one for
keeping the structure alive, one for preventing unmount and one for
tracking active writers. Exact values of these counters are very rarely
needed, which makes them a prime candidate for conversion to a per-cpu
scheme, resulting in much better performance.
Sample benchmark performing fstatfs (modifying 2 out of 3 counters) on
a 104-way 2 socket Skylake system:
before: 852393 ops/s
after: 76682077 ops/s
Reviewed by: kib, jeff
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21637
New primitive is introduced to denote sections can operate locklessly
on aspects of struct mount, but which can also be disabled if necessary.
This provides an opportunity to start scaling common case modifications
while providing stable state of the struct when facing unmount, write
suspendion or other events.
mnt_ref is the first counter to start being managed in this manner with
the intent to make it per-cpu.
Reviewed by: kib, jeff
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21425
After all the changes, its dynamic scope is same as for MNTK_UNMOUNT,
but to allow the syncer vnode to be re-installed on unmount failure.
But the case of syncer was already handled by using the VV_FORCEINSMQ
flag for quite some time.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
fs-specific part of vfs_statfs routines only fill in small portion of the
structure. Previous code was always copying everything at a higher layer to
acoomodate it and this patch does the same.
'df' (no arguments) worked fine because the caller uses mnt_stat itself as the
target buffer, making all the copying a no-op for its own case.
'df /' and similar use a different consumer which passes its own buffer and
this is where you can run into trouble.
Reported by: cy
Fixes: r351193
Sponsored by: The FreeBSD Foundation
The struct is already populated on each mount (and remount). Fields are either
constant or not used by filesystem in the first place.
Some infrequently used functions use it to avoid having to allocate a new buffer
and are left alone.
The current code results in an avoidable copying single-threaded and significant
cache line bouncing multithreaded
While here deduplicate initial filling of the struct.
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21317
Similar to r348026, exhaustive search for uses of CTRn() and cross reference
ktr.h includes. Where it was obvious that an OS compat header of some kind
included ktr.h indirectly, .c files were left alone. Some of these files
clearly got ktr.h via header pollution in some scenarios, or tinderbox would
not be passing prior to this revision, but go ahead and explicitly include it
in files using it anyway.
Like r348026, these CUs did not show up in tinderbox as missing the include.
Reported by: peterj (arm64/mp_machdep.c)
X-MFC-With: r347984
Sponsored by: Dell EMC Isilon
be called before VFS_ROOT() is called. Move the call for VFS_STATFS()
so that it is done after VFS_MOUNT(), but before VFS_ROOT().
This change actually improves the robustness of the mount system
call because it returns an error rather than failing silently
when VFS_STATFS() returns failure.
Reported by: Rebecca Cran <rebecca@bluestop.org>
Sponsored by: Netflix
check-hash fails. Panic'ing is not an appropriate response. So, check
for an error return from VFS_ROOT() and when an error is reported,
unwind and return the error.
Reported by: Gary Jennejohn (gj)
Sponsored by: Netflix
Use bypass to catch any NFS VOP dispatch and route it through the
wrapper which does sigdeferstop() and then dispatches original
VOP. NFS does not need a bypass below it, which is not supported.
The vop offset in the vop_vector is added since otherwise it is
impossible to get vop_op_t from the internal table, and I did not
wanted to create the layered fs only to wrap NFS VOPs.
VFS_OP()s wrap is straightforward.
Requested and reviewed by: mjg (previous version)
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D17658
by doing most of the work in a new function prison_add_vfs in kern_jail.c
Now a jail-enabled filesystem need only mark itself with VFCF_JAIL, and
the rest is taken care of. This includes adding a jail parameter like
allow.mount.foofs, and a sysctl like security.jail.mount_foofs_allowed.
Both of these used to be a static list of known filesystems, with
predefined permission bits.
Reviewed by: kib
Differential Revision: D14681
If the operation is not an update, if neither r/w nor r/o mode is
explicitly requested, if the error code hints at the possibility of the
media being read-only, and if the fallback is allowed, then we can try
to automatically downgrade to the readonly mode.
This is especially useful for auto-mounting of removable media that
sometimes can happen to be write-protected.
The fallback to r/o is not enabled by default. It can be requested on a
per-mount basis with a new mount option, 'autoro'. Or it can be
globally allowed by setting vfs.default_autoro.
Reviewed by: cem, kib
MFC after: 3 weeks
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D13361
