- don't unlock the vnode after vinvalbuf() only to have to relock it
almost immediately.
- don't refer to devices classified by vn_isdisk() as block devices.
operators) in and near revs.1.169-1.170 (open mode bandaid). This
(or better a proper fix) should have been done before cloning the
bandaid to many other file systems.
- rev.1.42 of ffs_readwrite.c added a special case in ffs_read() for reads
that are initially at EOF, and rev.1.62 of ufs_readwrite.c fixed
timestamp bugs in it. Removal of most of vfs_ioopt made it just and
optimization, and removal of the vm object reference calls made it less
than an optimization. It was cloned in rev.1.94 of ufs_readwrite.c as
part of cloning ffs_extwrite() although it was always less than an
optimization in ffs_extwrite().
- some comments, compound statements and vertical whitespace were vestiges
of dead code.
- struct plimit includes a mutex to protect a reference count. The plimit
structure is treated similarly to struct ucred in that is is always copy
on write, so having a reference to a structure is sufficient to read from
it without needing a further lock.
- The proc lock protects the p_limit pointer and must be held while reading
limits from a process to keep the limit structure from changing out from
under you while reading from it.
- Various global limits that are ints are not protected by a lock since
int writes are atomic on all the archs we support and thus a lock
wouldn't buy us anything.
- All accesses to individual resource limits from a process are abstracted
behind a simple lim_rlimit(), lim_max(), and lim_cur() API that return
either an rlimit, or the current or max individual limit of the specified
resource from a process.
- dosetrlimit() was renamed to kern_setrlimit() to match existing style of
other similar syscall helper functions.
- The alpha OSF/1 compat layer no longer calls getrlimit() and setrlimit()
(it didn't used the stackgap when it should have) but uses lim_rlimit()
and kern_setrlimit() instead.
- The svr4 compat no longer uses the stackgap for resource limits calls,
but uses lim_rlimit() and kern_setrlimit() instead.
- The ibcs2 compat no longer uses the stackgap for resource limits. It
also no longer uses the stackgap for accessing sysctl's for the
ibcs2_sysconf() syscall but uses kernel_sysctl() instead. As a result,
ibcs2_sysconf() no longer needs Giant.
- The p_rlimit macro no longer exists.
Submitted by: mtm (mostly, I only did a few cleanups and catchups)
Tested on: i386
Compiled on: alpha, amd64
and ffs_write(). These calls trace their origins to the dead vfs_ioopt
code, first appearing in revision 1.39 of ufs_readwrite.c.
Observed by: bde
Discussed with: tegge
Replace wrong check returned EFBIG with EOVERFLOW handling from POSIX:
36708 [EOVERFLOW] The file is a regular file, nbyte is greater than 0, the
starting position is before the end-of-file, and the starting position is
greater than or equal to the offset maximum established in the open file
description associated with fildes.
ffs_write:
Replace u_int64_t cast with uoff_t cast which is more natural for types
used.
ffs_write & ffs_read:
Remove uio_offset and uio_resid checks for negative values, the caller
supposed to do it already. Add comments about it.
Reviewed by: bde
Move diagnostic printf after vget. This might delay the debug
output some, but at least it keeps kernel from exploding if
DEBUG_VFS_LOCKS is in effect.
system super block after fsck has repaired the file system. The value of
fs_ronly was getting overwritten, which caused ffs_update() to attempt to
update inode timestamps even though the file system was still mounted
read-only.
This fixes the "giving up on N buffers" error that is triggered by running
fsck on the root file system and then rebooting without mounting the file
system read-write.
of newfs, to signify the newfs operation has not yet completed. Re-
write the superblock with the correct magic number once all of the
cylinder groups have been created to show the operation has finished.
Sponsored by: St. Bernard Software
accurate reporting of multi-terabyte filesystem sizes.
You should build and boot a new kernel BEFORE doing a `make world'
as the new kernel will know about binaries using the old statfs
structure, but an old kernel will not know about the new system
calls that support the new statfs structure. Running an old kernel
after a `make world' will cause programs such as `df' that do a
statfs system call to fail with a bad system call.
Reviewed by: Bruce Evans <bde@zeta.org.au>
Reviewed by: Tim Robbins <tjr@freebsd.org>
Reviewed by: Julian Elischer <julian@elischer.org>
Reviewed by: the hoards of <arch@freebsd.org>
Sponsored by: DARPA & NAI Labs.
Introduce two new macros MNT_ILOCK(mp)/MNT_IUNLOCK(mp) to
operate on this mutex transparently.
Eventually new mutex will be protecting more fields in
struct mount, not only vnode list.
Discussed with: jeff
wasn't curthread, i.e. when we receive a thread pointer to use
as a function argument. Use VOP_UNLOCK/vrele in these cases.
The only case there td != curthread known at the moment is
boot() calling sync with thread0 pointer.
This fixes the panic on shutdown people have reported.
those cylinder groups that have at least 75% of the average free
space per cylinder group for that file system are considered as
candidates for the creation of a new directory. The previous formula
for minbfree would set it to zero if the file system was more than
75% full, which allowed cylinder groups with no free space at all
to be chosen as candidates for directory creation, which resulted
in an expensive search for free blocks for each file that was
subsequently created in that directory.
Modify the calculation of minifree in the same way.
Decrease maxcontigdirs as the file system fills to decrease the
likelyhood that a cluster of directories will overflow the available
space in a cylinder group.
Reviewed by: mckusick
Tested by: kmarx@vicor.com
MFC after: 2 weeks
so make the code slightly more uniform. The vnode lock is acquired in
all cases and now the only difference between VCHR and other is we
call UFS_UPDATE instead of VOP_FSYNC().
- Slightly rewrite the fsync loop to be more lock friendly. We must
acquire the vnode interlock before dropping the mnt lock. We must
also check XLOCK to prevent vclean() races.
- Use LK_INTERLOCK in the vget() in ffs_sync to further prevent vclean()
races.
- Use a local variable to store the results of the nvp == TAILQ_NEXT
test so that we do not access the vp after we've vrele()d it.
- Add an XXX comment about UFS_UPDATE() not being protected by any lock
here. I suspect that it should need the VOP lock.
we release the mntvnode_mtx.
- Call vgonel() directly instead of going through vrecycle() since we own
the interlock now.
- Remove a few cases where we locked the interlock just so that we could
call VOP_UNLOCK with interlock held.
mntvnode_mtx.
- Use a local variable to store the results of the test to see if the
next vnode on the mount list has changed. This is so that we no longer
acess the vnode after we vput() it.
in a list head instead of a pointer to the first element at the time of
the first call. These lists are subject to change, and getdirtybuf()
would refetch from the wrong list in some cases.
Spottedy by: tegge
Pointy hat to: me
bail out if the buffer is not already present.
- The buffer returned by incore() is not locked and should not be sent to
brelse(). Use getblk() with the new GB_NOCREAT flag to preserve the
desired semantics.
caller to acquire it. This permits drain_output() to be done atomically
with other operations as well as reducing the number of lock operations.
- Assert that the proper locks are held in drain_output().
- Change getdirtybuf() to accept a mutex as an argument. This mutex is used
to protect the vnode's buf list and the BKGRDWAIT flag. This lock is
dropped when we successfully acquire a buffer and held on return
otherwise. These semantics reduce the number of cumbersome cases in
calling code.
- Pass the mtx from getdirtybuf() into interlocked_sleep() and allow this
mutex to be used as the interlock argument to BUF_LOCK() in the LOCKBUF
case of interlocked_sleep().
- Change the return value of getdirtybuf() to be the resulting locked buffer
or NULL otherwise. This is for callers who pass in a list head that
requires a lock. It is necessary since the lock that protects the list
head must be dropped in getdirtybuf() so that we don't have a lock order
reversal with the buf queues lock in bremfree().
- Adjust all callers of getdirtybuf() to match the new semantics.
- Add a comment in indir_trunc() that points at unlocked access to a buf.
This may also be one of the last instances of incore() in the tree.
- Surround all accesses of the BKGRD{WAIT,INPROG} flags with the vnode
interlock.
- Don't use the B_LOCKED flag and QUEUE_LOCKED for background write
buffers. Check for the BKGRDINPROG flag before recycling or throwing
away a buffer. We do this instead because it is not safe for us to move
the original buffer to a new queue from the callback on the background
write buffer.
- Remove the B_LOCKED flag and the locked buffer queue. They are no longer
used.
- The vnode interlock is used around checks for BKGRDINPROG where it may
not be strictly necessary. If we hold the buf lock the a back-ground
write will not be started without our knowledge, one may only be
completed while we're not looking. Rather than remove the code, Document
two of the places where this extra locking is done. A pass should be
done to verify and minimize the locking later.
get the same value from ip->i_ump->um_devvp.
This saves a pointer in the memory copies of inodes, which can
easily run into several hundred kilobytes.
The extra indirection is unmeasurable in benchmarks.
Approved by: mckusick
generate the inode mode from a default ACL and creation mask,
implement ufs_sync_inode_from_acl() using acl_posix1e_newfilemode().
Since ACL_OVERRIDE_MASK/ACL_PRESERVE_MASK are defined, we no
longer need to explicitly pass in a "preserve_mask" field: this
is implicit in the use of POSIX.1e semantics.
Note: this change contains a semantic bugfix for new file creation:
we now intersect the ACL-generated mode and the cmode requested by
the user process. This means permissions on newly created file
objects will now be more conservative. In the future, we may want
to provide alternative semantics (similar to Solaris and Linux) in
which the ACL mask overrides the umask, permitting ACLs to broaden
the rights beyond the requested umask.
PR: 50148
Reported by: Ritz, Bruno <bruno_ritz@gmx.ch>
Obtained from: TrustedBSD Project
cases:
- Setting sticky bit on non-directory
- Setting setgid on a file with a group that isn't in the effective
or extended groups of the authorizing credential
I.e., test the requirement first, then do the privilege test,
rather than doing the privilege test regardless of the need for
privilege.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
kernel ACL interfaces and system call names.
Break out UFS2 and FFS extattr delete and list vnode operations from
setextattr and getextattr to deleteextattr and listextattr, which
cleans up the implementations, and makes the results more readable,
and makes the APIs more clear.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
contain the filedescriptor number on opens from userland.
The index is used rather than a "struct file *" since it conveys a bit
more information, which may be useful to in particular fdescfs and /dev/fd/*
For now pass -1 all over the place.
UFS quota implementation. Push some quite broken access control
logic out of ufs_quotactl() into the individual command
implementations in ufs_quota.c; fix that logic. Pass in the thread
argument to any quotactl command that will need to perform access
control.
o quotaon() requires privilege (PRISON_ROOT).
o quotaoff() requires privilege (PRISON_ROOT).
o getquota() requires that:
If the type is USRQUOTA, either the effective uid match the
requested quota ID, that the unprivileged_get_quota flag be
set, or that the thread be privileged (PRISON_ROOT).
If the type is GRPQUOTA, require that either the thread be
a member of the group represented by the requested quota ID,
that the unprivileged_get_quota flag be set, or that the
thread be privileged (PRISON_ROOT).
o setquota() requires privilege (PRISON_ROOT).
o setuse() requires privilege (PRISON_ROOT).
o qsync() requires no special privilege (consistent with what
was present before, but probably not very useful).
Add a new sysctl, security.bsd.unprivileged_get_quota, which when
set to a non-zero value, will permit unprivileged users to query user
quotas with non-matching uids and gids. Set this to 0 by default
to be mostly consistent with the previous behavior (the same for
USRQUOTA, but not for GRPQUOTA).
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
attribute name of "" from ffs_getextattr(). Invoking VOP_GETETATTR()
with an empty name is now no longer supported; user application
compatibility is provided by a system call level compatibility
wrapper. We make sure to explicitly reject attempts to set an EA
with the name "".
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
extended attribute retrieval code: it's no longer special-cased,
and is caught by the normal UFS1 EA validity checks (and, in
fact, returns the same error, EINVAL).
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
if we permit them to occur, the kernel panics due to our performing
EA operations using VOP_STRATEGY on the vnode. This went unnoticed
previously because there are very for users of device nodes on UFS2
due to the introduction of devfs. However, this can come up with
the Linux compat directories and its hard-coded dev nodes (which will
need to go away as we move away from hard-coded device numbers).
This can come up if you use EA-intensive features such as ACLs and
MAC.
The proper fix is pretty complicated, but this band-aid would be
an excellent MFC candidate for the release.
only while holding appropriate vnode locks. This patch slides the lock
release for ufs_extattr_enable() to continue to hold the active vnode lock
on a backing file until after the flag change; it also acquires a vnode
lock when disabling an attribute and hence clearing a flag on the backing
vnode. This permits VFS_DEBUG_LOCKS to run UFS1 extended attributes
without panicking, as well as preventing a potential race and vnode flag
problem.
Approved by: re (jhb)
Pointed out by: DEBUG_VFS_LOCKS
These fields can be left as NULL if ffs_vget() allocates an inode but
fails before the dinode memory has been allocated. There are two cases
when this can occur: when we lose a race and another process has added
the inode to the hash, and when reading the inode off disk fails.
The bug was observed by Kris on one of the package-building machines.
See http://marc.theaimsgroup.com/?l=freebsd-current&m=105172731013411&w=2
In Kris's case, it was the bread() that failed because of a disk error.
The alternative to this patch is to ensure that ffs_vget() does not call
vput() when the inode that hasn't been properly initialised.
kg_nice is now protected by both. Being protected by both means that
other places in the kernel that want to read kg_nice only need one of the
two locks.
requiring locked bufs in vfs_bio_awrite(). Previously the buf could
have been written out by fsync before we acquired the buf lock if it
weren't for giant. The cluster_wbuild() handles this race properly but
the single write at the end of vfs_bio_awrite() would not.
- Modify flushbufqueues() so there is only one copy of the loop. Pass a
parameter in that says whether or not we should sync bufs with deps.
- Call flushbufqueues() a second time and then break if we couldn't find
any bufs without deps.
of a snapshot's copy of a superblock. This patch fixes a panic
when taking a snapshot of a 4096/512 filesystem.
Reported by: Ian Freislich <ianf@za.uu.net>
Sponsored by: DARPA & NAI Labs.
- Define one flag GB_LOCK_NOWAIT that tells getblk() to pass the LK_NOWAIT
flag to the initial BUF_LOCK(). This will eventually be used in cases
were we want to use a buffer only if it is not currently in use.
- Convert all consumers of the getblk() api to use this extra parameter.
Reviwed by: arch
Not objected to by: mckusick
Remove extraneous uses of vop_null, instead defering to the default op.
Rename vnode type "vfs" to the more descriptive "syncer".
Fix formatting for various filesystems that use vop_print.
from the filesystem size field to the filesystem maximum blocksize
field. The problem is that older versions of growfs updated only the
new size field and not the old size field. This resulted in the old
(smaller) size field being copied up to the new size field which
caused the filesystem to appear to fsck to be badly trashed.
This also adds a sanity check to ensure that the superblock is not
being updated when the filesystem is mounted read-only. Obviously
such an update should never happen.
Reported by: Nate Lawson <nate@root.org>
Sponsored by: DARPA & NAI Labs.
- Remove the buftimelock mutex and acquire the buf's interlock to protect
these fields instead.
- Hold the vnode interlock while locking bufs on the clean/dirty queues.
This reduces some cases from one BUF_LOCK with a LK_NOWAIT and another
BUF_LOCK with a LK_TIMEFAIL to a single lock.
Reviewed by: arch, mckusick
a snapshot. As part of taking a snapshot of a filesystem, the kernel
builds up a list of the filesystem metadata (such as the cylinder
group bitmaps) that are contained in the snapshot. When doing a
copy-on-write check, the list is first consulted. If the block being
written is found on the list, then the full snapshot lookup can be
avoided. Besides providing an important performance speedup this
check also avoids a potential deadlock between the code creating
the snapshot and the bufdaemon trying to cleanup snapshot related
buffers. This fix creates a temporary list containing the key
metadata blocks that can cause the deadlock. This temporary list
is used between the time that the snapshot is first enabled and the
time that the fully complete list is built.
Reported by: Attila Nagy <bra@fsn.hu>
Sponsored by: DARPA & NAI Labs.
is being taken from panicing with either "freeing free block" or
"freeing free inode". The problem arises when the snapshot code
is scanning the filesystem looking for inodes with a reference
count of zero (e.g., unlinked but still open) so that it can
expunge them from its view. If it encounters a reclaimed vnode
and has to restart its scan, then it will panic if it encounters
and tries to free an inode that it has already processed. The fix
is to check each candidate inode to see if it has already been
processed before trying to delete it from the snapshot image.
Sponsored by: DARPA & NAI Labs.
that they convert to 64-bit values before shifting rather than
afterwards. Once fixed, they can be used rather than inline expanded.
Sponsored by: DARPA & NAI Labs.
values for the initial inode generation numbers in newfs and for
newly allocated inode generation numbers in the kernel.
Submitted by: Theo de Raadt <deraadt@cvs.openbsd.org>
Sponsored by: DARPA & NAI Labs.
that is protected by the vnode lock.
- Move B_SCANNED into b_vflags and call it BV_SCANNED.
- Create a vop_stdfsync() modeled after spec's sync.
- Replace spec_fsync, msdos_fsync, and hpfs_fsync with the stdfsync and some
fs specific processing. This gives all of these filesystems proper
behavior wrt MNT_WAIT/NOWAIT and the use of the B_SCANNED flag.
- Annotate the locking in buf.h
pointer types, and remove a huge number of casts from code using it.
Change struct xfile xf_data to xun_data (ABI is still compatible).
If we need to add a #define for f_data and xf_data we can, but I don't
think it will be necessary. There are no operational changes in this
commit.
padding is not specific to non-i386 architectures. It is
caused by non-i386 specific alignment requirements of
fs_swuid,
o Add a CTASSERT to catch a change in the size of struct fs
at compile-time rather than run-time.
Ok'd: gordon
Tested on: i386 ia64
will be used to support volume names with the help of a GEOM module (to be
committed). uuid will be used to deal with conflicting volume names (which
doesn't work just yet).
Approved by: mckusick@
repeatedly truncate the same file. Each time the file is truncated,
a buffer is grabbed to store the indirect block numbers that need
to be freed. Those blocks cannot be freed until the inode claiming
them is written to disk. Thus, the number of buffers being held by
soft updates explodes and in extreme cases can run the kernel out
of buffers. The problem can be avoided by doing an fsync on the
file every debug.maxindirdep truncates (currently defaulted to 50).
The fsync causes the inode to be written so that the held buffers
can be freed. The check for excessive buffers is checked as part
of the existing hook for excessive dependencies (softdep_slowdown)
in the truncate code.
Reported by: David Schultz <dschultz@uclink.Berkeley.EDU>
Sponsored by: DARPA & NAI Labs.
MFC after: 3 weeks
to sort out disk-io from file-io in the vm/buffer/filesystem space.
The intent is to sort VOP_STRATEGY calls into those which operate
on "real" vnodes and those which operate on VCHR vnodes. For
the latter kind, the call will be changed to VOP_SPECSTRATEGY,
possibly conditionally for those places where dual-use happens.
Add a default VOP_SPECSTRATEGY method which will call the normal
VOP_STRATEGY. First time it is called it will print debugging
information. This will only happen if a normal vnode is passed
to VOP_SPECSTRATEGY by mistake.
Add a real VOP_SPECSTRATEGY in specfs, which does what VOP_STRATEGY
does on a VCHR vnode today.
Add a new VOP_STRATEGY method in specfs to catch instances where
the conversion to VOP_SPECSTRATEGY has not yet happened. Handle
the request just like we always did, but first time called print
debugging information.
Apart up to two instances of console messages per boot, this amounts
to a glorified no-op commit.
If you get any of the messages on your console I would very much
like a copy of them mailed to phk@freebsd.org
kern/vfs_defaults.c it is wrong for the individual filesystems to use
the std* functions as that prevents override of the default.
Found by: src/tools/tools/vop_table
this was causing filedesc work to be very painful.
In order to make this work split out sigio definitions to thier own header
(sigio.h) which is included from proc.h for the time being.
Remove the malloctype from the ufs mount structure, instead add a callback
to the storage method for freeing inodes: UFS_IFREE().
Add vfs_ifree() method function which frees an inode.
Unvariablelize the malloc type used for allocating inodes.
so as to work correctly on 64-bit platforms.
Reported-by: Jake Burkholder <jake@locore.ca>
Sponsored by: DARPA & NAI Labs.
Approved by: Ian Dowse <iedowse@maths.tcd.ie>
that were copied in all of the earlier snapshots, thus its precomputed
list must be used in the copyonwrite test. Using incomplete lists may
lead to deadlock. Also do not include the blocks used for the indirect
pointers in the indirect pointers as this may lead to inconsistent
snapshots.
Sponsored by: DARPA & NAI Labs.
Approved by: re
previously allocated block as the previous use of the block may
have fallen out of the cache. Failure to reread its contents cause
zeroed results to be written instead of the proper contents.
Conversely, when the block is going to be entirely filled in, it
is not necessary reread the old contents.
Sponsored by: DARPA & NAI Labs.
Approved by: re
converting from individual vnode locks to the snapshot
lock, be sure to pass any waiting processes along to the
new lock as well. This transfer is done by a new function
in the lock manager, transferlockers(from_lock, to_lock);
Thanks to Lamont Granquist <lamont@scriptkiddie.org> for
his help in pounding on snapshots beyond all reason and
finding this deadlock.
Sponsored by: DARPA & NAI Labs.
1) Release the snapshot file lock while suspending the system. Otherwise
a process trying to read the lock may block on its containing directory
preventing the suspension from completing. Thanks to Sean Kelly
<smkelly@zombie.org> for finding this deadlock.
2) Replace some bdwrite's with bawrite's so as not to fill all the
buffers with dirty data. The buffers could not be cleaned as the
snapshot vnode was locked hence the system could deadlock when
making snapshots of really massive filesystems. Thanks to
Hidetoshi Shimokawa <simokawa@sat.t.u-tokyo.ac.jp> for figuring
this out.
Sponsored by: DARPA & NAI Labs.
before using it to write the superblock. This is to guard against
accidentally trashing the disklabel if the superblock format missed
being upgraded by the new kernel.
Reported by: Sam Leffler <sam@errno.com>
Sponsored by: DARPA & NAI Labs.
Approved by: Murray Stokely <murray@FreeBSD.org>
the old 8-bit fs_old_flags to the new location the first time that the
filesystem is mounted by a new kernel. One of the unused flags in
fs_old_flags is used to indicate that the flags have been moved.
Leave the fs_old_flags word intact so that it will work properly if
used on an old kernel.
Change the fs_sblockloc superblock location field to be in units
of bytes instead of in units of filesystem fragments. The old units
did not work properly when the fragment size exceeeded the superblock
size (8192). Update old fs_sblockloc values at the same time that
the flags are moved.
Suggested by: BOUWSMA Barry <freebsd-misuser@netscum.dyndns.dk>
Sponsored by: DARPA & NAI Labs.
in half because of reports that under heavy load the kernel could
exhaust its memory pool. The limit is now (desiredvnodes * 4)
rather than (desiredvnodes * 8), so it will still scale with
larger systems, just not as quickly.
Sponsored by: DARPA & NAI Labs.
not have hit the disk and the dependencies cannot be unrolled.
In this case, the system will mark the buffer as dirty again so
that the write can be retried in the future. When the write
succeeds or the system gives up on the buffer and marks it as
invalid (B_INVAL), the dependencies will be cleared.
Sponsored by: DARPA & NAI Labs.
"refreshing" the label on the vnode before use, just get the label
right from inception. For single-label file systems, set the label
in the generic VFS getnewvnode() code; for multi-label file systems,
leave the labeling up to the file system. With UFS1/2, this means
reading the extended attribute during vfs_vget() as the inode is
pulled off disk, rather than hitting the extended attributes
frequently during operations later, improving performance. This
also corrects sematics for shared vnode locks, which were not
previously present in the system. This chances the cache
coherrency properties WRT out-of-band access to label data, but in
an acceptable form. With UFS1, there is a small race condition
during automatic extended attribute start -- this is not present
with UFS2, and occurs because EAs aren't available at vnode
inception. We'll introduce a work around for this shortly.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
check for and/or report I/O errors. The result is that a VFS_SYNC
or VOP_FSYNC called with MNT_WAIT could loop infinitely on ufs in
the presence of a hard error writing a disk sector or in a filesystem
full condition. This patch ensures that I/O errors will always be
checked and returned. This patch also ensures that every call to
VFS_SYNC or VOP_FSYNC with MNT_WAIT set checks for and takes
appropriate action when an error is returned.
Sponsored by: DARPA & NAI Labs.
the ffs_copyonwrite routine to avoid a deadlock between the syncer
daemon trying to sync out a snapshot vnode and the bufdaemon
trying to write out a buffer containing the snapshot inode.
With any luck this will be the last snapshot race condition.
Sponsored by: DARPA & NAI Labs.
a full filesystem. Previously, if the allocation failed, we had to
fsync the file before rolling back any partial allocation of indirect
blocks. Most block allocation requests only need to allocate a single
data block and if that allocation fails, there is nothing to unroll.
So, before doing the fsync, we check to see if any rollback will
really be necessary. If none is necessary, then we simply return.
This update eliminates the flurry of disk activity that got triggered
whenever a filesystem would run out of space.
Sponsored by: DARPA & NAI Labs.
that works in the new threaded kernel. It was commented out of
the disksort routine earlier this year for the reasons given in
kern/subr_disklabel.c (which is where this code used to reside
before it moved to kern/subr_disk.c):
----------------------------
revision 1.65
date: 2002/04/22 06:53:20; author: phk; state: Exp; lines: +5 -0
Comment out Kirks io-request priority hack until we can do this in a
civilized way which doesn't cause grief.
The problem is that it is not generally safe to cast a "struct bio
*" to a "struct buf *". Things like ccd, vinum, ata-raid and GEOM
constructs bio's which are not entrails of a struct buf.
Also, curthread may or may not have anything to do with the I/O request
at hand.
The correct solution can either be to tag struct bio's with a
priority derived from the requesting threads nice and have disksort
act on this field, this wouldn't address the "silly-seek syndrome"
where two equal processes bang the diskheads from one edge to the
other of the disk repeatedly.
Alternatively, and probably better: a sleep should be introduced
either at the time the I/O is requested or at the time it is completed
where we can be sure to sleep in the right thread.
The sleep also needs to be in constant timeunits, 1/hz can be practicaly
any sub-second size, at high HZ the current code practically doesn't
do anything.
----------------------------
As suggested in this comment, it is no longer located in the disk sort
routine, but rather now resides in spec_strategy where the disk operations
are being queued by the thread that is associated with the process that
is really requesting the I/O. At that point, the disk queues are not
visible, so the I/O for positively niced processes is always slowed
down whether or not there is other activity on the disk.
On the issue of scaling HZ, I believe that the current scheme is
better than using a fixed quantum of time. As machines and I/O
subsystems get faster, the resolution on the clock also rises.
So, ten years from now we will be slowing things down for shorter
periods of time, but the proportional effect on the system will
be about the same as it is today. So, I view this as a feature
rather than a drawback. Hence this patch sticks with using HZ.
Sponsored by: DARPA & NAI Labs.
Reviewed by: Poul-Henning Kamp <phk@critter.freebsd.dk>
