Disable the normal reclaim path for zpl_putpage(). This ensures that
all memory allocations under this call path will never enter direct
reclaim. If this were to happen the VM might try to write out
additional pages by calling zpl_putpage() again resulting in a
deadlock.
This sitution is typically handled in Linux by marking each offending
allocation GFP_NOFS. However, since much of the code used is common
it makes more sense to use PF_MEMALLOC to flag the entire call tree.
Alternately, the code could be updated to pass the needed allocation
flags but that's a more invasive change.
The following example of the above described deadlock was triggered
by test 074 in the xfstest suite.
Call Trace:
[<ffffffff814dcdb2>] down_write+0x32/0x40
[<ffffffffa05af6e4>] dnode_new_blkid+0x94/0x2d0 [zfs]
[<ffffffffa0597d66>] dbuf_dirty+0x556/0x750 [zfs]
[<ffffffffa05987d1>] dmu_buf_will_dirty+0x81/0xd0 [zfs]
[<ffffffffa059ee70>] dmu_write+0x90/0x170 [zfs]
[<ffffffffa0611afe>] zfs_putpage+0x2ce/0x360 [zfs]
[<ffffffffa062875e>] zpl_putpage+0x1e/0x60 [zfs]
[<ffffffffa06287b2>] zpl_writepage+0x12/0x20 [zfs]
[<ffffffff8115f907>] writeout+0xa7/0xd0
[<ffffffff8115fa6b>] move_to_new_page+0x13b/0x170
[<ffffffff8115fed4>] migrate_pages+0x434/0x4c0
[<ffffffff811559ab>] compact_zone+0x4fb/0x780
[<ffffffff81155ed1>] compact_zone_order+0xa1/0xe0
[<ffffffff8115602c>] try_to_compact_pages+0x11c/0x190
[<ffffffff811200bb>] __alloc_pages_nodemask+0x5eb/0x8b0
[<ffffffff8115464a>] alloc_pages_current+0xaa/0x110
[<ffffffff8111e36e>] __get_free_pages+0xe/0x50
[<ffffffffa03f0e2f>] kv_alloc+0x3f/0xb0 [spl]
[<ffffffffa03f11d9>] spl_kmem_cache_alloc+0x339/0x660 [spl]
[<ffffffffa05950b3>] dbuf_create+0x43/0x370 [zfs]
[<ffffffffa0596fb1>] __dbuf_hold_impl+0x241/0x480 [zfs]
[<ffffffffa0597276>] dbuf_hold_impl+0x86/0xc0 [zfs]
[<ffffffffa05977ff>] dbuf_hold_level+0x1f/0x30 [zfs]
[<ffffffffa05a9dde>] dmu_tx_check_ioerr+0x4e/0x110 [zfs]
[<ffffffffa05aa1f9>] dmu_tx_count_write+0x359/0x6f0 [zfs]
[<ffffffffa05aa5df>] dmu_tx_hold_write+0x4f/0x70 [zfs]
[<ffffffffa0611a6d>] zfs_putpage+0x23d/0x360 [zfs]
[<ffffffffa062875e>] zpl_putpage+0x1e/0x60 [zfs]
[<ffffffff811221f9>] write_cache_pages+0x1c9/0x4a0
[<ffffffffa0628738>] zpl_writepages+0x18/0x20 [zfs]
[<ffffffff81122521>] do_writepages+0x21/0x40
[<ffffffff8119bbbd>] writeback_single_inode+0xdd/0x2c0
[<ffffffff8119bfbe>] writeback_sb_inodes+0xce/0x180
[<ffffffff8119c11b>] writeback_inodes_wb+0xab/0x1b0
[<ffffffff8119c4bb>] wb_writeback+0x29b/0x3f0
[<ffffffff8119c6cb>] wb_do_writeback+0xbb/0x240
[<ffffffff811308ea>] bdi_forker_task+0x6a/0x310
[<ffffffff8108ddf6>] kthread+0x96/0xa0
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#327
When modifing overlapping regions of a file using mmap(2) and
write(2)/read(2) it is possible to deadlock due to a lock inversion.
The zfs_write() and zfs_read() hooks first take the zfs range lock
and then lock the individual pages. Conversely, when using mmap'ed
I/O the zpl_writepage() hook is called with the individual page
locks already taken and then zfs_putpage() takes the zfs range lock.
The most straight forward fix is to simply not take the zfs range
lock in the mmap(2) case. The individual pages will still be locked
thus serializing access. Updating the same region of a file with
write(2) and mmap(2) has always been a dodgy thing to do. This change
at a minimum ensures we don't deadlock and is consistent with the
existing Linux semantics enforced by the VFS.
This isn't an issue under Solaris because the only range locking
performed will be with the zfs range locks. It's up to each filesystem
to perform its own file locking. Under Linux the VFS provides many
of these services.
It may be possible/desirable at a latter date to entirely dump the
existing zfs range locking and rely on the Linux VFS page locks.
However, for now its safest to perform both layers of locking until
zfs is more tightly integrated with the page cache.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #302
This commit fixes a regression which was accidentally introduced by
the Linux 2.6.39 compatibility chanages. As part of these changes
instead of holding an active reference on the namepsace (which is
no longer posible) a reference is taken on the super block. This
reference ensures the super block remains valid while it is in use.
To handle the unlikely race condition of the filesystem being
unmounted concurrently with the start of a 'zfs send/recv' the
code was updated to only take the super block reference when there
was an existing reference. This indicates that the filesystem is
active and in use.
Unfortunately, in the 'zfs recv' case this is not the case. The
newly created dataset will not have a super block without an
active reference which results in the 'dataset is busy' error.
The most straight forward fix for this is to simply update the
code to always take the reference even when it's zero. This
may expose us to very very unlikely concurrent umount/send/recv
case but the consequences of that are minor.
Closes#319
There is at most a factor of 3x performance improvement to be
had by using the Linux generic_fillattr() helper. However, to
use it safely we need to ensure the values in a cached inode
are kept rigerously up to date. Unfortunately, this isn't
the case for the blksize, blocks, and atime fields. At the
moment the authoritative values are still stored in the znode.
This patch introduces an optimized zfs_getattr_fast() call.
The idea is to use the up to date values from the inode and
the blksize, block, and atime fields from the znode. At some
latter date we should be able to strictly use the inode values
and further improve performance.
The remaining overhead in the zfs_getattr_fast() call can be
attributed to having to take the znode mutex. This overhead is
unavoidable until the inode is kept strictly up to date. The
the careful reader will notice the we do not use the customary
ZFS_ENTER()/ZFS_EXIT() macros. These macro's are designed to
ensure the filesystem is not torn down in the middle of an
operation. However, in this case the VFS is holding a
reference on the active inode so we know this is impossible.
=================== Performance Tests ========================
This test calls the fstat(2) system call 10,000,000 times on
an open file description in a tight loop. The test results
show the zfs stat(2) performance is now only 22% slower than
ext4. This is a 2.5x improvement and there is a clear long
term plan to get to parity with ext4.
filesystem | test-1 test-2 test-3 | average | times-ext4
--------------+-------------------------+---------+-----------
ext4 | 7.785s 7.899s 7.284s | 7.656s | 1.000x
zfs-0.6.0-rc4 | 24.052s 22.531s 23.857s | 23.480s | 3.066x
zfs-faststat | 9.224s 9.398s 9.485s | 9.369s | 1.223x
The second test is to run 'du' of a copy of the /usr tree
which contains 110514 files. The test is run multiple times
both using both a cold cache (/proc/sys/vm/drop_caches) and
a hot cache. As expected this change signigicantly improved
the zfs hot cache performance and doesn't quite bring zfs to
parity with ext4.
A little surprisingly the zfs cold cache performance is better
than ext4. This can probably be attributed to the zfs allocation
policy of co-locating all the meta data on disk which minimizes
seek times. By default the ext4 allocator will spread the data
over the entire disk only co-locating each directory.
filesystem | cold | hot
--------------+---------+--------
ext4 | 13.318s | 1.040s
zfs-0.6.0-rc4 | 4.982s | 1.762s
zfs-faststat | 4.933s | 1.345s
The performance of the L2ARC can be tweaked by a number of tunables, which
may be necessary for different workloads:
l2arc_write_max max write bytes per interval
l2arc_write_boost extra write bytes during device warmup
l2arc_noprefetch skip caching prefetched buffers
l2arc_headroom number of max device writes to precache
l2arc_feed_secs seconds between L2ARC writing
l2arc_feed_min_ms min feed interval in milliseconds
l2arc_feed_again turbo L2ARC warmup
l2arc_norw no reads during writes
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#316
The remaining code that is guarded by HAVE_SHARE ifdefs is related to the
.zfs/shares functionality which is currently not available on Linux.
On Solaris the .zfs/shares directory can be used to set permissions for
SMB shares.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The sharenfs and sharesmb properties depend on the libshare library
to export datasets via NFS and SMB. This commit implements the base
libshare functionality as well as support for managing NFS shares.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Under Linux you may only disable USER xattrs. The SECURITY,
SYSTEM, and TRUSTED xattr namespaces must always be available
if xattrs are supported by the filesystem. The enforcement
of USER xattrs is performed in the zpl_xattr_user_* handlers.
Under Solaris there is only a single xattr namespace which
is managed globally.
The Linux kernel already has support for mandatory locking. This
change just replaces the Solaris mandatory locking calls with the
Linux equivilants. In fact, it looks like this code could be
removed entirely because this checking is already done generically
in the Linux VFS. However, for now we'll leave it in place even
if it is redundant just in case we missed something.
The original patch to update the code to support mandatory locking
was done by Rohan Puri. This patch is an updated version which is
compatible with the previous mount option handling changes.
Original-Patch-by: Rohan Puri <rohan.puri15@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#222Closes#253
The .get_sb callback has been replaced by a .mount callback
in the file_system_type structure. When using the new
interface the caller must now use the mount_nodev() helper.
Unfortunately, the new interface no longer passes the vfsmount
down to the zfs layers. This poses a problem for the existing
implementation because we currently save this pointer in the
super block for latter use. It provides our only entry point
in to the namespace layer for manipulating certain mount options.
This needed to be done originally to allow commands like
'zfs set atime=off tank' to work properly. It also allowed me
to keep more of the original Solaris code unmodified. Under
Solaris there is a 1-to-1 mapping between a mount point and a
file system so this is a fairly natural thing to do. However,
under Linux they many be multiple entries in the namespace
which reference the same filesystem. Thus keeping a back
reference from the filesystem to the namespace is complicated.
Rather than introduce some ugly hack to get the vfsmount and
continue as before. I'm leveraging this API change to update
the ZFS code to do things in a more natural way for Linux.
This has the upside that is resolves the compatibility issue
for the long term and fixes several other minor bugs which
have been reported.
This commit updates the code to remove this vfsmount back
reference entirely. All modifications to filesystem mount
options are now passed in to the kernel via a '-o remount'.
This is the expected Linux mechanism and allows the namespace
to properly handle any options which apply to it before passing
them on to the file system itself.
Aside from fixing the compatibility issue, removing the
vfsmount has had the benefit of simplifying the code. This
change which fairly involved has turned out nicely.
Closes#246Closes#217Closes#187Closes#248Closes#231
The security_inode_init_security() function now takes an additional
qstr argument which must be passed in from the dentry if available.
Passing a NULL is safe when no qstr is available the relevant
security checks will just be skipped.
Closes#246Closes#217Closes#187
Under Linux the VFS handles virtually all of the mmap() access
checks. Filesystem specific checks are left to be handled in
the .mmap() hook and normally there arn't any.
However, ZFS provides a few attributes which can influence the
mmap behavior and should be honored. Note, currently the code
to modify these attributes has not been implemented under Linux.
* ZFS_IMMUTABLE | ZFS_READONLY | ZFS_APPENDONLY: when any of these
attributes are set a file may not be mmaped with write access.
* ZFS_AV_QUARANTINED: when set a file file may not be mmaped with
read or exec access.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The following functions were required for the OpenSolaris mmap
implementation. Because the Linux VFS does most the most heavy
lifting for us they are not required and are being removed to
keep the code clean and easy to understand.
* zfs_null_putapage()
* zfs_frlock()
* zfs_no_putpage()
Signed-off-by: Brian Behlendorf <behlendorf@llnl.gov>
Enable zfs_getpage, zfs_fillpage, zfs_putpage, zfs_putapage functions.
The functions have been modified to make them Linux friendly.
ZFS uses these functions to read/write the mmapped pages. Using them
from readpage/writepage results in clear code. The patch also adds
readpages and writepages interface functions to read/write list of
pages in one function call.
The code change handles the first mmap optimization mentioned on
https://github.com/behlendorf/zfs/issues/225
Signed-off-by: Prasad Joshi <pjoshi@stec-inc.com>
Signed-off-by: Brian Behlendorf <behlendorf@llnl.gov>
Issue #255
According to Linux kernel commit 2c27c65e, using truncate_setsize in
setattr simplifies the code. Therefore, the patch replaces the call
to vmtruncate() with truncate_setsize().
zfs_setattr uses zfs_freesp to free the disk space belonging to the
file. As truncate_setsize may release the page cache and flushing
the dirty data to disk, it must be called before the zfs_freesp.
Suggested-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Prasad Joshi <pjoshi@stec-inc.com>
Closes#255
The inode eviction should unmap the pages associated with the inode.
These pages should also be flushed to disk to avoid the data loss.
Therefore, use truncate_setsize() in evict_inode() to release the
pagecache.
The API truncate_setsize() was added in 2.6.35 kernel. To ensure
compatibility with the old kernel, the patch defines its own
truncate_setsize function.
Signed-off-by: Prasad Joshi <pjoshi@stec-inc.com>
Closes#255
To accomindate the updated Linux 3.0 shrinker API the spl
shrinker compatibility code was updated. Unfortunately, this
couldn't be done cleanly without slightly adjusting the comapt
API. See spl commit a55bcaad18.
This commit updates the ZFS code to use the slightly modified
API. You must use the latest SPL if your building ZFS.
The problem here is that prune_icache() tries to evict/delete
both the xattr directory inode as well as at least one xattr
inode contained in that directory. Here's what happens:
1. File is created.
2. xattr is created for that file (behind the scenes a xattr
directory and a file in that xattr directory are created)
3. File is deleted.
4. Both the xattr directory inode and at least one xattr
inode from that directory are evicted by prune_icache();
prune_icache() acquires a lock on both inodes before it
calls ->evict() on the inodes
When the xattr directory inode is evicted zfs_zinactive attempts
to delete the xattr files contained in that directory. While
enumerating these files zfs_zget() is called to obtain a reference
to the xattr file znode - which tries to lock the xattr inode.
However that very same xattr inode was already locked by
prune_icache() further up the call stack, thus leading to a
deadlock.
This can be reliably reproduced like this:
$ touch test
$ attr -s a -V b test
$ rm test
$ echo 3 > /proc/sys/vm/drop_caches
This patch fixes the deadlock by moving the zfs_purgedir() call to
zfs_unlinked_drain(). Instead zfs_rmnode() now checks whether the
xattr dir is empty and leaves the xattr dir in the unlinked set if
it finds any xattrs.
To ensure zfs_unlinked_drain() never accesses a stale super block
zfsvfs_teardown() has been update to block until the iput taskq
has been drained. This avoids a potential race where a file with
an xattr directory is removed and the file system is immediately
unmounted.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#266
iput_final() already calls zpl_inode_destroy() -> zfs_inode_destroy()
for us after zfs_zinactive(), thus making sure that the inode is
properly cleaned up.
The zfs_inode_destroy() calls in zfs_rmnode() would lead to a
double-free.
Fixes#282
Some disks with internal sectors larger than 512 bytes (e.g., 4k) can
suffer from bad write performance when ashift is not configured
correctly. This is caused by the disk not reporting its actual sector
size, but a sector size of 512 bytes. The drive may behave this way
for compatibility reasons. For example, the WDC WD20EARS disks are
known to exhibit this behavior.
When creating a zpool, ZFS takes that wrong sector size and sets the
"ashift" property accordingly (to 9: 1<<9=512), whereas it should be
set to 12 for 4k sectors (1<<12=4096).
This patch allows an adminstrator to manual specify the known correct
ashift size at 'zpool create' time. This can significantly improve
performance in certain cases. However, it will have an impact on your
total pool capacity. See the updated ashift property description
in the zpool.8 man page for additional details.
Valid values for the ashift property range from 9 to 17 (512B-128KB).
Additionally, you may set the ashift to 0 if you wish to auto-detect
the sector size based on what the disk reports, this is the default
behavior. The most common ashift values are 9 and 12.
Example:
zpool create -o ashift=12 tank raidz2 sda sdb sdc sdd
Closes#280
Original-patch-by: Richard Laager <rlaager@wiktel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The WRITE_FLUSH, WRITE_FUA, and WRITE_FLUSH_FUA flags have been
introduced as a replacement for WRITE_BARRIER. This was done
to allow richer semantics to be expressed to the block layer.
It is the block layers responsibility to choose the correct way
to implement these semantics.
This change simply updates the bio's to use the new kernel API
which should be absolutely safe. However, since ZFS depends
entirely on this working as designed for correctness we do
want to be careful.
Closes#281
Stack usage for ddt_class_contains() reduced from 524 bytes to 68
bytes. This large stack allocation significantly contributed to
the likelyhood of a stack overflow when scrubbing/resilvering
dedup pools.
Stack usage for ddt_zap_lookup() reduced from 368 bytes to 120
bytes. This large stack allocation significantly contributed to
the likelyhood of a stack overflow when scrubbing/resilvering
dedup pools.
This abomination is no longer required because the zio's issued
during this recursive call path will now be handled asynchronously
by the taskq thread pool.
This reverts commit 6656bf5621.
The majority of the recursive operations performed by the dsl
are done either in the context of the tgx_sync_thread or during
pool import. It is these recursive operations which contribute
greatly to the stack depth. When this recursion is coupled with
a synchronous I/O in the same context overflow becomes possible.
Previously to handle this case I have focused on keeping the
individual stack frames as light as possible. This is a good
idea as long as it can be done in a way which doesn't overly
complicate the code. However, there is a better solution.
If we treat all zio's issued by the tgx_sync_thread as async then
we can use the tgx_sync_thread stack for the recursive parts, and
the zio_* threads for the I/O parts. This effectively doubles our
available stack space with the only drawback being a small delay
to schedule the I/O. However, in practice the scheduling time
is so much smaller than the actual I/O time this isn't an issue.
Another benefit of making the zio async is that the zio pipeline
is now parallel. That should mean for CPU intensive pipelines
such as compression or dedup performance may be improved.
With this change in place the worst case stack usage observed so
far is 6902 bytes. This is still higher than I'd like but
significantly improved. Additional changes to specific functions
should improve this further. This change allows us to revent
commit 6656bf5 which did some horrible things to the recursive
traverse_visitbp() callpath in the name of saving stack.
Yesterday I ran across a 3TB drive which exposed 4K sectors to
Linux. While I thought I had gotten this support correct it
turns out there were 2 subtle bugs which prevented it from
working.
sudo ./cmd/zpool/zpool create -f large-sector /dev/sda
cannot create 'large-sector': one or more devices is currently unavailable
1) The first issue was that it was possible that bdev_capacity()
would return the number of 512 byte sectors rather than the number
of 4096 sectors. Internally, certain Linux functions only operate
with 512 byte sectors so you need to be careful. To avoid any
confusion in the future I've updated bdev_capacity() to simply
return the device (or partition) capacity in bytes. The higher
levels of ZFS want the value in bytes anyway so this is cleaner.
2) When creating a bio the ->bi_sector count must always be
expressed in 512 byte sectors. The existing code would scale
the byte offset by the logical sector size. Until now this was
always 512 so it never caused problems. Trying a 4K sector drive
clearly exposed the issue. The problem has been fixed by
hard coding the 512 byte sector which is exactly what the bio
code does internally.
With these changes I'm now able to create ZFS pools using 4K
sector drives. No issues were observed during fairly extensive
testing. This is also a low risk change if your using 512b
sectors devices because none of the logic changes.
Closes#256
The default buffer size when requesting multiple quota entries
is 100 times the zfs_useracct_t size. In practice this works out
to exactly 27200 bytes. Since this will be a short lived buffer
in a non-performance critical path it is preferable to vmem_alloc()
the needed memory.
Initially when zfsdev_ioctl() was ported to Linux we didn't have
any credential support implemented. So at the time we simply
passed NULL which wasn't much of a problem since most of the
secpolicy code was disabled.
However, one exception is quota handling which does require the
credential. Now that proper credentials are supported we can
safely start passing the callers credential. This is also an
initial step towards fully implemented the zfs secpolicy.
Normally when the arc_shrinker_func() function is called the return
value should be:
>=0 - To indicate the number of freeable objects in the cache, or
-1 - To indicate this cache should be skipped
However, when the shrinker callback is called with 'nr_to_scan' equal
to zero. The caller simply wants the number of freeable objects in
the cache and we must never return -1. This patch reorders the
first two conditionals in arc_shrinker_func() to ensure this behavior.
This patch also now explictly casts arc_size and arc_c_min to signed
int64_t types so MAX(x, 0) works as expected. As unsigned types
we would never see an negative value which defeated the purpose of
the MAX() lower bound and broke the shrinker logic.
Finally, when nr_to_scan is non-zero we explictly prevent all reclaim
below arc_c_min. This is done to prevent the Linux page cache from
completely crowding out the ARC. This limit is tunable and some
experimentation is likely going to be required to set it exactly right.
For now we're sticking with the OpenSolaris defaults.
Closes#218Closes#243
The comment in zfs_close() pertaining to decrementing the synchronous
open count needs to be updated for Linux. The code was already
updated to be correct, but the comment was missed and is now misleading.
Under Linux the zfs_close() hook is only called once when the final
reference is dropped. This differs from Solaris where zfs_close()
is called for each close.
Closes#237
Update the handling of named pipes and sockets to be consistent with
other platforms with regard to the rdev attribute. While all ZFS
ipmlementations store the rdev for device files in a system attribute
(SA), this is not the case for FIFOs and sockets. Indeed, Linux always
passes rdev=0 to mknod() for FIFOs and sockets, so the value is not
needed. Add an ASSERT that rdev==0 for FIFOs and sockets to detect if
the expected behavior ever changes.
Closes#216
The direct reclaim path in the z_wr_* threads must be disabled
to ensure forward progress is always maintained for txg processing.
This ensures that a txg will never get stuck waiting on itself
because it entered the following memory reclaim callpath.
->prune_icache()->dispose_list()->zpl_clear_inode()->zfs_inactive()
->dmu_tx_assign()->dmu_tx_wait()->tgx_wait_open()
It would be preferable to target this exact code path but the
kernel offers no way to do this without custom patches. To avoid
this we are forced to disable all reclaim for these threads. It
should not be necessary to do this for other other z_* threads
because they will not hold a txg open.
Closes#232
How nfsd handles .fsync() has been changed a couple of times in the
recent kernels. But basically there are three cases we need to
consider.
Linux 2.6.12 - 2.6.33
* The .fsync() hook takes 3 arguments
* The nfsd will call .fsync() with a NULL file struct pointer.
Linux 2.6.34
* The .fsync() hook takes 3 arguments
* The nfsd no longer calls .fsync() but instead used sync_inode()
Linux 2.6.35 - 2.6.x
* The .fsync() hook takes 2 arguments
* The nfsd no longer calls .fsync() but instead used sync_inode()
For once it looks like we've gotten lucky. The first two cases can
actually be collased in to one if we stop using the file struct
pointer entirely. Since the dentry is still passed in both cases
this is possible. The last case can then be safely handled by
unconditionally using the dentry in the file struct pointer now
that we know the nfsd caller has been removed.
Closes#230
The default buffer size when requesting history is 128k. This
is far to large for a kmem_alloc() so instead use the slower
vmem_alloc(). This path has no performance concerns and the
buffer is immediately free'd after its contents are copied to
the user space buffer.
This commit adds module options for all existing zfs tunables.
Ideally the average user should never need to modify any of these
values. However, in practice sometimes you do need to tweak these
values for one reason or another. In those cases it's nice not to
have to resort to rebuilding from source. All tunables are visable
to modinfo and the list is as follows:
$ modinfo module/zfs/zfs.ko
filename: module/zfs/zfs.ko
license: CDDL
author: Sun Microsystems/Oracle, Lawrence Livermore National Laboratory
description: ZFS
srcversion: 8EAB1D71DACE05B5AA61567
depends: spl,znvpair,zcommon,zunicode,zavl
vermagic: 2.6.32-131.0.5.el6.x86_64 SMP mod_unload modversions
parm: zvol_major:Major number for zvol device (uint)
parm: zvol_threads:Number of threads for zvol device (uint)
parm: zio_injection_enabled:Enable fault injection (int)
parm: zio_bulk_flags:Additional flags to pass to bulk buffers (int)
parm: zio_delay_max:Max zio millisec delay before posting event (int)
parm: zio_requeue_io_start_cut_in_line:Prioritize requeued I/O (bool)
parm: zil_replay_disable:Disable intent logging replay (int)
parm: zfs_nocacheflush:Disable cache flushes (bool)
parm: zfs_read_chunk_size:Bytes to read per chunk (long)
parm: zfs_vdev_max_pending:Max pending per-vdev I/Os (int)
parm: zfs_vdev_min_pending:Min pending per-vdev I/Os (int)
parm: zfs_vdev_aggregation_limit:Max vdev I/O aggregation size (int)
parm: zfs_vdev_time_shift:Deadline time shift for vdev I/O (int)
parm: zfs_vdev_ramp_rate:Exponential I/O issue ramp-up rate (int)
parm: zfs_vdev_read_gap_limit:Aggregate read I/O over gap (int)
parm: zfs_vdev_write_gap_limit:Aggregate write I/O over gap (int)
parm: zfs_vdev_scheduler:I/O scheduler (charp)
parm: zfs_vdev_cache_max:Inflate reads small than max (int)
parm: zfs_vdev_cache_size:Total size of the per-disk cache (int)
parm: zfs_vdev_cache_bshift:Shift size to inflate reads too (int)
parm: zfs_scrub_limit:Max scrub/resilver I/O per leaf vdev (int)
parm: zfs_recover:Set to attempt to recover from fatal errors (int)
parm: spa_config_path:SPA config file (/etc/zfs/zpool.cache) (charp)
parm: zfs_zevent_len_max:Max event queue length (int)
parm: zfs_zevent_cols:Max event column width (int)
parm: zfs_zevent_console:Log events to the console (int)
parm: zfs_top_maxinflight:Max I/Os per top-level (int)
parm: zfs_resilver_delay:Number of ticks to delay resilver (int)
parm: zfs_scrub_delay:Number of ticks to delay scrub (int)
parm: zfs_scan_idle:Idle window in clock ticks (int)
parm: zfs_scan_min_time_ms:Min millisecs to scrub per txg (int)
parm: zfs_free_min_time_ms:Min millisecs to free per txg (int)
parm: zfs_resilver_min_time_ms:Min millisecs to resilver per txg (int)
parm: zfs_no_scrub_io:Set to disable scrub I/O (bool)
parm: zfs_no_scrub_prefetch:Set to disable scrub prefetching (bool)
parm: zfs_txg_timeout:Max seconds worth of delta per txg (int)
parm: zfs_no_write_throttle:Disable write throttling (int)
parm: zfs_write_limit_shift:log2(fraction of memory) per txg (int)
parm: zfs_txg_synctime_ms:Target milliseconds between tgx sync (int)
parm: zfs_write_limit_min:Min tgx write limit (ulong)
parm: zfs_write_limit_max:Max tgx write limit (ulong)
parm: zfs_write_limit_inflated:Inflated tgx write limit (ulong)
parm: zfs_write_limit_override:Override tgx write limit (ulong)
parm: zfs_prefetch_disable:Disable all ZFS prefetching (int)
parm: zfetch_max_streams:Max number of streams per zfetch (uint)
parm: zfetch_min_sec_reap:Min time before stream reclaim (uint)
parm: zfetch_block_cap:Max number of blocks to fetch at a time (uint)
parm: zfetch_array_rd_sz:Number of bytes in a array_read (ulong)
parm: zfs_pd_blks_max:Max number of blocks to prefetch (int)
parm: zfs_dedup_prefetch:Enable prefetching dedup-ed blks (int)
parm: zfs_arc_min:Min arc size (ulong)
parm: zfs_arc_max:Max arc size (ulong)
parm: zfs_arc_meta_limit:Meta limit for arc size (ulong)
parm: zfs_arc_reduce_dnlc_percent:Meta reclaim percentage (int)
parm: zfs_arc_grow_retry:Seconds before growing arc size (int)
parm: zfs_arc_shrink_shift:log2(fraction of arc to reclaim) (int)
parm: zfs_arc_p_min_shift:arc_c shift to calc min/max arc_p (int)
When a new znode/inode pair is created both the znode and the inode
should be immediately updated to the correct values. This was done
for the znode and for most of the values in the inode, but not all
of them. This normally wasn't a problem because most subsequent
operations would cause the inode to be immediately updated. This
change ensures the inode is now fully updated before it is inserted
in to the inode hash.
Closes#116Closes#146Closes#164
This change fixes a kernel panic which would occur when resizing
a dataset which was not open. The objset_t stored in the
zvol_state_t will be set to NULL when the block device is closed.
To avoid this issue we pass the correct objset_t as the third arg.
The code has also been updated to correctly notify the kernel
when the block device capacity changes. For 2.6.28 and newer
kernels the capacity change will be immediately detected. For
earlier kernels the capacity change will be detected when the
device is next opened. This is a known limitation of older
kernels.
Online ext3 resize test case passes on 2.6.28+ kernels:
$ dd if=/dev/zero of=/tmp/zvol bs=1M count=1 seek=1023
$ zpool create tank /tmp/zvol
$ zfs create -V 500M tank/zd0
$ mkfs.ext3 /dev/zd0
$ mkdir /mnt/zd0
$ mount /dev/zd0 /mnt/zd0
$ df -h /mnt/zd0
$ zfs set volsize=800M tank/zd0
$ resize2fs /dev/zd0
$ df -h /mnt/zd0
Original-patch-by: Fajar A. Nugraha <github@fajar.net>
Closes#68Closes#84
The vdev_metaslab_init() function has been observed to allocate
larger than 8k chunks. However, they are not much larger than 8k
and it does this infrequently so it is allowed and the warning is
supressed.
The dsl_scan_visit() function is a little heavy weight taking 464
bytes on the stack. This can be easily reduced for little cost by
moving zap_cursor_t and zap_attribute_t off the stack and on to the
heap. After this change dsl_scan_visit() has been reduced in size
by 320 bytes.
This change was made to reduce stack usage in the dsl_scan_sync()
callpath which is recursive and has been observed to overflow the
stack.
Issue #174
This function is called recursively so everything possible must be
done to limit its stack consumption. The dprintf_bp() debugging
function adds 30 bytes of local variables to the function we cannot
afford. By commenting out this debugging we save 30 bytes per
recursion and depths of 13 are not uncommon. This yeilds a total
stack saving of 390 bytes on our 8k stack.
Issue #174
The recursive call chain dsl_scan_visitbp() -> dsl_scan_recurse() ->
dsl_scan_visitdnode() -> dsl_scan_visitbp has been observed to consume
considerable stack resulting in a stack overflow (>8k). The cleanest
way I see to fix this with minimal impact to the existing flow of
code, and with the fewest performance concerns, is to always inline
dsl_scan_recurse() and dsl_scan_visitdnode(). While this will increase
the function size of dsl_scan_visitbp(), by 4660 bytes, it also reduces
the stack requirements by removing the function call overhead.
Issue #174
It's possible for a zvol_write thread to enter direct memory reclaim
while holding open a transaction group. This results in the system
attempting to write out data to the disk to free memory. Unfortunately,
this can't succeed because the the thread doing reclaim is holding open
the txg which must be closed to be synced to disk. To prevent this
the offending allocation is marked KM_PUSHPAGE which will prevent it
from attempting writeback.
Closes#191
Occasionally we would see an -EFAULT returned when setting the
I/O scheduler on a vdev. This was caused an improperly formatted
user mode helper command.
This commit restructures the command to something simpler, allocates
space for it dynamically to save stack, and removes the retry logic
which is no longer needed.
Closes#169
This change ensures the ARC meta-data limits are enforced. Without
this enforcement meta-data can grow to consume all of the ARC cache
pushing out data and hurting performance. The cache is aggressively
reclaimed but this is a soft and not a hard limit. The cache may
exceed the set limit briefly before being brought under control.
By default 25% of the ARC capacity can be used for meta-data. This
limit can be tuned by setting the 'zfs_arc_meta_limit' module option.
Once this limit is exceeded meta-data reclaim will occur in 3 percent
chunks, or may be tuned using 'arc_reduce_dnlc_percent'.
Closes#193
Fixed a bug where zfs_zget could access a stale znode pointer when
the inode had already been removed from the inode cache via iput ->
iput_final -> ... -> zfs_zinactive but the corresponding SA handle
was still alive.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#180
As part of zfs_ioc_recv() a zfs_cmd_t is allocated in the kernel
which is 17808 bytes in size. This sort of thing in general should
be avoided. However, since this should be an infrequent event for
now we allow it and simply suppress the warning with the KM_NODEBUG
flag. This can be revisited latter if/when it becomes an issue.
Closes#178
If the attribute's new value was shorter than the old one the old
code would leave parts of the old value in the xattr znode.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#203
