Commit graph

18562 commits

Author SHA1 Message Date
Sage Weil f0b18d9f22 ceph: sync header defs with server code
Define ROLLBACK op, IFLOCK inode lock (for advisory file locking).

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:42 -07:00
Sage Weil 5cd068c200 ceph: clean up header guards
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:42 -07:00
Sage Weil 9688f19a18 ceph: strip misleading/obsolete version, feature info
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:41 -07:00
Sage Weil 6a2593823a ceph: specify supported features in super.h
Specify the supported/required feature bits in super.h client code instead
of using the definitions from the shared kernel/userspace headers (which
will go away shortly).

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:41 -07:00
Sage Weil c309f0ab26 ceph: clean up fsid mount option
Specify the fsid mount option in hex, not via the major/minor u64 hackery we had
before.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:41 -07:00
Sage Weil e0f9f9ee8f ceph: remove unused 'monport' mount option
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:41 -07:00
Greg Farnum e55b71f802 ceph: handle ESTALE properly; on receipt send to authority if it wasn't
Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:41 -07:00
Greg Farnum 2bc50259fa ceph: add ceph_get_cap_for_mds function.
Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:41 -07:00
Sage Weil 154f42c2c3 ceph: connect to export targets on cap export
When we get a cap EXPORT message, make sure we are connected to all export
targets to ensure we can handle the matching IMPORT.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:41 -07:00
Sage Weil cb170a2215 ceph: connect to export targets if mds is laggy
If an MDS we are talking to may have failed, we need to open sessions to
its potential export targets to ensure that any in-progress migration that
may have involved some of our caps is properly handled.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:40 -07:00
Sage Weil ed0552a1a2 ceph: introduce helper to connect to mds export targets
There are a few cases where we need to open sessions with a given mds's
potential export targets.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:40 -07:00
Sage Weil 796d6955a5 ceph: only set num_pages in calc_layout
Setting it elsewhere is unnecessary and more fragile.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:40 -07:00
Yehuda Sadeh 37151668ba ceph: do caps accounting per mds_client
Caps related accounting is now being done per mds client instead
of just being global. This prepares ground work for a later revision
of the caps preallocated reservation list.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:40 -07:00
Sage Weil 0deb01c999 ceph: track laggy state of mds from mdsmap
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:40 -07:00
Yehuda Sadeh cd84db6e40 ceph: code cleanup
Mainly fixing minor issues reported by sparse.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:40 -07:00
Sage Weil ca81f3f6bd ceph: skip if no auth cap in flush_snaps
If we have a capsnap but no auth cap (e.g. because it is migrating to
another mds), bail out and do nothing for now.  Do NOT remove the capsnap
from the flush list.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:39 -07:00
Sage Weil 3b454c4945 ceph: simplify caps revocation, fix for multimds
The caps revocation should either initiate writeback, invalidateion, or
call check_caps to ack or do the dirty work.  The primary question is
whether we can get away with only checking the auth cap or whether all
caps need to be checked.

The old code was doing...something else.  At the very least, revocations
from non-auth MDSs could break by triggering the "check auth cap only"
case.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:39 -07:00
Sage Weil 38e8883ee3 ceph: simplify add_cap_releases
No functional change, aside from more useful debug output.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:39 -07:00
Sage Weil ee6b272b9c ceph: drop unused argument
Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:39 -07:00
Sage Weil 2962507ca2 ceph: perform lazy reads when file mode and caps permit
If the file mode is marked as "lazy," perform cached/buffered reads when
the caps permit it.  Adjust the rdcache_gen and invalidation logic
accordingly so that we manage our cache based on the FILE_CACHE -or-
FILE_LAZYIO cap bits.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:39 -07:00
Sage Weil 33caad324b ceph: perform lazy writes when file mode and caps permit
If we have marked a file as "lazy" (using the ceph ioctl), perform buffered
writes when the MDS caps allow it.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:39 -07:00
Sage Weil 8c6e9229fc ceph: add LAZYIO ioctl to mark a file description for lazy consistency
Allow an application to mark a file descriptor for lazy file consistency
semantics, allowing buffered reads and writes when multiple clients are
accessing the same file.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:39 -07:00
Sage Weil 84d9509234 ceph: request FILE_LAZYIO cap when LAZY file mode is set
Also clean up the file flags -> file mode -> wanted caps functions while
we're at it.  This resyncs this file with userspace.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-08-01 20:11:38 -07:00
Trond Myklebust 77a63f3d1e NFS: Fix a typo in include/linux/nfs_fs.h
nfs_commit_inode() needs to be defined irrespectively of whether or not
we are supporting NFSv3 and NFSv4.

Allow the compiler to optimise away code in the NFSv2-only case by
converting it into an inlined stub function.

Reported-and-tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-01 15:10:01 -07:00
Linus Torvalds fc71ff8a6c Merge branch 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6
* 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6:
  NFS: Ensure that writepage respects the nonblock flag
  NFS: kswapd must not block in nfs_release_page
  nfs: include space for the NUL in root path
2010-07-30 19:02:21 -07:00
David Howells 51c20fcced CIFS: Remove __exit mark from cifs_exit_dns_resolver()
Remove the __exit mark from cifs_exit_dns_resolver() as it's called by the
module init routine in case of error, and so may have been discarded during
linkage.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-07-30 18:56:09 -07:00
Trond Myklebust cfb506e1d3 NFS: Ensure that writepage respects the nonblock flag
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2010-07-30 15:38:56 -04:00
Trond Myklebust b608b283a9 NFS: kswapd must not block in nfs_release_page
See https://bugzilla.kernel.org/show_bug.cgi?id=16056

If other processes are blocked waiting for kswapd to free up some memory so
that they can make progress, then we cannot allow kswapd to block on those
processes.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org
2010-07-30 15:38:42 -04:00
Dan Carpenter 674b222292 nfs: include space for the NUL in root path
In root_nfs_name() it does the following:

        if (strlen(buf) + strlen(cp) > NFS_MAXPATHLEN) {
                printk(KERN_ERR "Root-NFS: Pathname for remote directory too long.\n");
                return -1;
        }
        sprintf(nfs_export_path, buf, cp);

In the original code if (strlen(buf) + strlen(cp) == NFS_MAXPATHLEN)
then the sprintf() would lead to an overflow.  Generally the rest of the
code assumes that the path can have NFS_MAXPATHLEN (1024) characters and
a NUL terminator so the fix is to add space to the nfs_export_path[]
buffer.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2010-07-30 15:33:39 -04:00
David Howells de09a9771a CRED: Fix get_task_cred() and task_state() to not resurrect dead credentials
It's possible for get_task_cred() as it currently stands to 'corrupt' a set of
credentials by incrementing their usage count after their replacement by the
task being accessed.

What happens is that get_task_cred() can race with commit_creds():

	TASK_1			TASK_2			RCU_CLEANER
	-->get_task_cred(TASK_2)
	rcu_read_lock()
	__cred = __task_cred(TASK_2)
				-->commit_creds()
				old_cred = TASK_2->real_cred
				TASK_2->real_cred = ...
				put_cred(old_cred)
				  call_rcu(old_cred)
		[__cred->usage == 0]
	get_cred(__cred)
		[__cred->usage == 1]
	rcu_read_unlock()
							-->put_cred_rcu()
							[__cred->usage == 1]
							panic()

However, since a tasks credentials are generally not changed very often, we can
reasonably make use of a loop involving reading the creds pointer and using
atomic_inc_not_zero() to attempt to increment it if it hasn't already hit zero.

If successful, we can safely return the credentials in the knowledge that, even
if the task we're accessing has released them, they haven't gone to the RCU
cleanup code.

We then change task_state() in procfs to use get_task_cred() rather than
calling get_cred() on the result of __task_cred(), as that suffers from the
same problem.

Without this change, a BUG_ON in __put_cred() or in put_cred_rcu() can be
tripped when it is noticed that the usage count is not zero as it ought to be,
for example:

kernel BUG at kernel/cred.c:168!
invalid opcode: 0000 [#1] SMP
last sysfs file: /sys/kernel/mm/ksm/run
CPU 0
Pid: 2436, comm: master Not tainted 2.6.33.3-85.fc13.x86_64 #1 0HR330/OptiPlex
745
RIP: 0010:[<ffffffff81069881>]  [<ffffffff81069881>] __put_cred+0xc/0x45
RSP: 0018:ffff88019e7e9eb8  EFLAGS: 00010202
RAX: 0000000000000001 RBX: ffff880161514480 RCX: 00000000ffffffff
RDX: 00000000ffffffff RSI: ffff880140c690c0 RDI: ffff880140c690c0
RBP: ffff88019e7e9eb8 R08: 00000000000000d0 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000040 R12: ffff880140c690c0
R13: ffff88019e77aea0 R14: 00007fff336b0a5c R15: 0000000000000001
FS:  00007f12f50d97c0(0000) GS:ffff880007400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8f461bc000 CR3: 00000001b26ce000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process master (pid: 2436, threadinfo ffff88019e7e8000, task ffff88019e77aea0)
Stack:
 ffff88019e7e9ec8 ffffffff810698cd ffff88019e7e9ef8 ffffffff81069b45
<0> ffff880161514180 ffff880161514480 ffff880161514180 0000000000000000
<0> ffff88019e7e9f28 ffffffff8106aace 0000000000000001 0000000000000246
Call Trace:
 [<ffffffff810698cd>] put_cred+0x13/0x15
 [<ffffffff81069b45>] commit_creds+0x16b/0x175
 [<ffffffff8106aace>] set_current_groups+0x47/0x4e
 [<ffffffff8106ac89>] sys_setgroups+0xf6/0x105
 [<ffffffff81009b02>] system_call_fastpath+0x16/0x1b
Code: 48 8d 71 ff e8 7e 4e 15 00 85 c0 78 0b 8b 75 ec 48 89 df e8 ef 4a 15 00
48 83 c4 18 5b c9 c3 55 8b 07 8b 07 48 89 e5 85 c0 74 04 <0f> 0b eb fe 65 48 8b
04 25 00 cc 00 00 48 3b b8 58 04 00 00 75
RIP  [<ffffffff81069881>] __put_cred+0xc/0x45
 RSP <ffff88019e7e9eb8>
---[ end trace df391256a100ebdd ]---

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-07-29 15:16:17 -07:00
Andre Osterhues a6f80fb7b5 ecryptfs: Bugfix for error related to ecryptfs_hash_buckets
The function ecryptfs_uid_hash wrongly assumes that the
second parameter to hash_long() is the number of hash
buckets instead of the number of hash bits.
This patch fixes that and renames the variable
ecryptfs_hash_buckets to ecryptfs_hash_bits to make it
clearer.

Fixes: CVE-2010-2492

Signed-off-by: Andre Osterhues <aosterhues@escrypt.com>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-07-28 19:59:24 -07:00
Linus Torvalds 6c50e1a49b Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph: use complete_all and wake_up_all
  ceph: Correct obvious typo of Kconfig variable "CRYPTO_AES"
  ceph: fix dentry lease release
  ceph: fix leak of dentry in ceph_init_dentry() error path
  ceph: fix pg_mapping leak on pg_temp updates
  ceph: fix d_release dop for snapdir, snapped dentries
  ceph: avoid dcache readdir for snapdir
2010-07-28 11:10:53 -07:00
Steven Whitehouse d2a97a4e99 GFS2: Use kmalloc when possible for ->readdir()
If we don't need a huge amount of memory in ->readdir() then
we can use kmalloc rather than vmalloc to allocate it. This
should cut down on the greater overheads associated with
vmalloc for smaller directories.

We may be able to eliminate vmalloc entirely at some stage,
but this is easy to do right away.

Also using GFP_NOFS to avoid any issues wrt to deleting inodes
while under a glock, and suggestion from Linus to factor out
the alloc/dealloc.

I've given this a test with a variety of different sized
directories and it seems to work ok.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-07-28 11:10:03 -07:00
Yehuda Sadeh 03066f2345 ceph: use complete_all and wake_up_all
This fixes an issue triggered by running concurrent syncs. One of the syncs
would go through while the other would just hang indefinitely. In any case, we
never actually want to wake a single waiter, so the *_all functions should
be used.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-07-27 13:11:17 -07:00
Latchesar Ionkov da7ddd3296 9p: Pass the correct end of buffer to p9stat_read
Pass the correct end of the buffer to p9stat_read.

Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
2010-07-27 14:52:04 -05:00
Eric W. Biederman d33002129e sysfs: allow creating symlinks from untagged to tagged directories
Supporting symlinks from untagged to tagged directories is reasonable,
and needed to support CONFIG_SYSFS_DEPRECATED.  So don't fail a prior
allowing that case to work.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-07-26 12:02:41 -07:00
Eric W. Biederman 521d045354 sysfs: sysfs_delete_link handle symlinks from untagged to tagged directories.
This happens for network devices when SYSFS_DEPRECATED is enabled.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-07-26 12:02:41 -07:00
Eric W. Biederman 96d6523adf sysfs: Don't allow the creation of symlinks we can't remove
Recently my tagged sysfs support revealed a flaw in the device core
that a few rare drivers are running into such that we don't always put
network devices in a class subdirectory named net/.

Since we are not creating the class directory the network devices wind
up in a non-tagged directory, but the symlinks to the network devices
from /sys/class/net are in a tagged directory.  All of which works
until we go to remove or rename the symlink.  When we remove or rename
a symlink we look in the namespace of the target of the symlink.
Since the target of the symlink is in a non-tagged sysfs directory we
don't have a namespace to look in, and we fail to remove the symlink.

Detect this problem up front and simply don't create symlinks we won't
be able to remove later.  This prevents symlink leakage and fails in
a much clearer and more understandable way.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-07-26 12:02:41 -07:00
Robert P. J. Day 25848b3ec6 ceph: Correct obvious typo of Kconfig variable "CRYPTO_AES"
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Sage Weil <sage@newdream.net>
2010-07-24 21:36:07 -07:00
Sage Weil 1dadcce358 ceph: fix dentry lease release
When we embed a dentry lease release notification in a request, invalidate
our lease so we don't think we still have it.  Otherwise we can get all
sorts of incorrect client behavior when multiple clients are interacting
with the same part of the namespace.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-07-23 13:54:21 -07:00
Sage Weil 8c696737aa ceph: fix leak of dentry in ceph_init_dentry() error path
If we fail to allocate a ceph_dentry_info, don't leak the dn reference.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-07-23 10:02:07 -07:00
Sage Weil bc4fdca857 ceph: fix pg_mapping leak on pg_temp updates
Free the ceph_pg_mapping structs when they are removed from the pg_temp
rbtree.  Also fix a leak in the __insert_pg_mapping() error path.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-07-23 10:02:06 -07:00
Sage Weil 252af52146 ceph: fix d_release dop for snapdir, snapped dentries
We need to set the d_release dop for snapdir and snapped dentries so that
the ceph_dentry_info struct gets released.  We also use the dcache to
cache readdir results when possible, which only works if we know when
dentries are dropped from the cache.  Since we don't use the dcache for
readdir in the hidden snapdir, avoid that case in ceph_dentry_release.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-07-23 10:02:05 -07:00
Sage Weil a0dff78dab ceph: avoid dcache readdir for snapdir
We should always go to the MDS for readdir on the hidden snapdir.  The
set of snapshots can change at any time; the client can't trust its cache
for that.

Signed-off-by: Sage Weil <sage@newdream.net>
2010-07-22 13:50:45 -07:00
David Howells 4c0c03ca54 CIFS: Fix a malicious redirect problem in the DNS lookup code
Fix the security problem in the CIFS filesystem DNS lookup code in which a
malicious redirect could be installed by a random user by simply adding a
result record into one of their keyrings with add_key() and then invoking a
CIFS CFS lookup [CVE-2010-2524].

This is done by creating an internal keyring specifically for the caching of
DNS lookups.  To enforce the use of this keyring, the module init routine
creates a set of override credentials with the keyring installed as the thread
keyring and instructs request_key() to only install lookup result keys in that
keyring.

The override is then applied around the call to request_key().

This has some additional benefits when a kernel service uses this module to
request a key:

 (1) The result keys are owned by root, not the user that caused the lookup.

 (2) The result keys don't pop up in the user's keyrings.

 (3) The result keys don't come out of the quota of the user that caused the
     lookup.

The keyring can be viewed as root by doing cat /proc/keys:

2a0ca6c3 I-----     1 perm 1f030000     0     0 keyring   .dns_resolver: 1/4

It can then be listed with 'keyctl list' by root.

	# keyctl list 0x2a0ca6c3
	1 key in keyring:
	726766307: --alswrv     0     0 dns_resolver: foo.bar.com

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-and-Tested-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Steve French <smfrench@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-07-22 09:42:40 -07:00
Linus Torvalds a4ce96ac35 Fix up trivial spelling errors ('taht' -> 'that')
Pointed out by Lucas who found the new one in a comment in
setup_percpu.c. And then I fixed the others that I grepped
for.

Reported-by: Lucas <canolucas@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-07-21 09:25:42 -07:00
Linus Torvalds e0959371b4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph: do not include cap/dentry releases in replayed messages
  ceph: reuse request message when replaying against recovering mds
  ceph: fix creation of ipv6 sockets
  ceph: fix parsing of ipv6 addresses
  ceph: fix printing of ipv6 addrs
  ceph: add kfree() to error path
  ceph: fix leak of mon authorizer
  ceph: fix message revocation
2010-07-20 16:27:58 -07:00
Linus Torvalds 620d0be881 Merge branch 'shrinker' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/xfsdev
* 'shrinker' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/xfsdev:
  xfs: track AGs with reclaimable inodes in per-ag radix tree
  xfs: convert inode shrinker to per-filesystem contexts
  mm: add context argument to shrinker callback
2010-07-19 20:18:24 -07:00
Linus Torvalds ee1039307a Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable
* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: fix checks in BTRFS_IOC_CLONE_RANGE
  Btrfs: fix CLONE ioctl destination file size expansion to block boundary
  Btrfs: fix split_leaf double split corner case
2010-07-19 19:33:02 -07:00
Dave Chinner 16fd536737 xfs: track AGs with reclaimable inodes in per-ag radix tree
https://bugzilla.kernel.org/show_bug.cgi?id=16348

When the filesystem grows to a large number of allocation groups,
the summing of recalimable inodes gets expensive. In many cases,
most AGs won't have any reclaimable inodes and so we are wasting CPU
time aggregating over these AGs. This is particularly important for
the inode shrinker that gets called frequently under memory
pressure.

To avoid the overhead, track AGs with reclaimable inodes in the
per-ag radix tree so that we can find all the AGs with reclaimable
inodes via a simple gang tag lookup. This involves setting the tag
when the first reclaimable inode is tracked in the AG, and removing
the tag when the last reclaimable inode is removed from the tree.
Then the summation process becomes a loop walking the radix tree
summing AGs with the reclaim tag set.

This significantly reduces the overhead of scanning - a 6400 AG
filesystea now only uses about 25% of a cpu in kswapd while slab
reclaim progresses instead of being permanently stuck at 100% CPU
and making little progress. Clean filesystems filesystems will see
no overhead and the overhead only increases linearly with the number
of dirty AGs.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-07-20 09:43:39 +10:00