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2009-08-17GFS2: Add some more info to ueventsSteven Whitehouse
With each uevent, we now always include the journal ID. We can't call it JID since that is already in use by some of the individual events relating to recovery, so we use JOURNALID instead. We don't send the JOURNALID for spectator mounts, since there isn't one. Also the ADD event now has both RDONLY and SPECTATOR information to match that of the ONLINE event. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2009-08-17GFS2: Add online uevent to GFS2Steven Whitehouse
We already have an offline uevent (used when a withdraw occurs) but no online uevent. This adds an online uevent so that userspace will be able to detect a successful mount by means other than not receiving a remove event after the add & recovery (change) uevents. It has also been added to the remount path as well - we can't use a change uevent there as older GFS2 userspace acts on change uevents according to the state that it thinks the fs is in, so we can't easily add any new ones. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2009-08-17xfs: fix locking in xfs_iget_cache_hitChristoph Hellwig
The locking in xfs_iget_cache_hit currently has numerous problems: - we clear the reclaim tag without i_flags_lock which protects modifications to it - we call inode_init_always which can sleep with pag_ici_lock held (this is oss.sgi.com BZ #819) - we acquire and drop i_flags_lock a lot and thus provide no consistency between the various flags we set/clear under it This patch fixes all that with a major revamp of the locking in the function. The new version acquires i_flags_lock early and only drops it once we need to call into inode_init_always or before calling xfs_ilock. This patch fixes a bug seen in the wild where we race modifying the reclaim tag. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Felix Blyakher <felixb@sgi.com> Reviewed-by: Eric Sandeen <sandeen@sandeen.net> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-15poll/select: initialize triggered field of struct poll_wqueuesGuillaume Knispel
The triggered field of struct poll_wqueues introduced in commit 5f820f648c92a5ecc771a96b3c29aa6e90013bba ("poll: allow f_op->poll to sleep"). It was first set to 1 in pollwake() (now __pollwake() ), tested and later set to 0 in poll_schedule_timeout(), but not initialized before. As a result when the process needs to sleep, triggered was likely to be non-zero even if pollwake() is not called before the first poll_schedule_timeout(), meaning schedule_hrtimeout_range() would not be called and an extra loop calling all ->poll() would be done. This patch initialize triggered to 0 in poll_initwait() so the ->poll() are not called twice before the process goes to sleep when it needs to. Signed-off-by: Guillaume Knispel <gknispel@proformatique.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-08-14nfs: nfs4xdr: optimize low level decodingBenny Halevy
do not increment decoding ptr if not needed. Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: get rid of READ_BUFBenny Halevy
Use xdr_inline_decode instead. Open code debug printout and error return. Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: simplify decode_exchange_id by reusing decode_opaque_inlineBenny Halevy
Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: get rid of COPYMEMBenny Halevy
Just directly call memcpy. Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: introduce decode_sessionid helperBenny Halevy
Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: introduce decode_verifier helperBenny Halevy
Signed-off-by: Benny Halevy <bhalevy@panasas.com> [Trond: Fixed up an 'uninitialised variable' issue in decode_readdir] Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: introduce decode_opaque_fixed and decode_stateid helpersBenny Halevy
Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: introduce print_overflow_msgBenny Halevy
Part fo the nfs4xdr cleanup. READ_BUF will go away. Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: get rid of READTIMEBenny Halevy
It has no users. Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: get rid of READ64Benny Halevy
s/READ64\(\*(.*)\)/p = xdr_decode_hyper(p, \1)/ s/READ64\((.*)\)/p = xdr_decode_hyper(p, &\1)/ Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: get rid of READ32Benny Halevy
s/READ32\((.*)\)/\1 = be32_to_cpup(p++)/ Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: merge xdr_encode_int+xdr_encode_opaque_fixed into ↵Benny Halevy
xdr_encode_opaque use encode_string where appropriate. Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: optimize low level encodingBenny Halevy
do not increment encoding ptr if not needed. Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: change RESERVE_SPACE macro into a static helperBenny Halevy
In order to open code and expose the result pointer assignment. Alternatively, we can open code the call to xdr_reserve_space and do the BUG_ON an the error case at the call site. Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: encode_compound_hdr does not have to round up reserved bytesBenny Halevy
This is already done by xdr_reserve_space and since encode_compound_hdr is adding a byte count to "12" which is already word aligned, the xdr level rounding will work just as well. Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: optimize RESERVE_SPACE in encode_create_session and ↵Benny Halevy
encode_sequence Coalesce multilpe constant RESERVE_SPACEs into one Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: get rid of WRITEMEMBenny Halevy
s/WRITEMEM(/p = xdr_encode_opaque_fixed(p, / Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: get rid of WRITE64Benny Halevy
s/WRITE64/p = xdr_encode_hyper(p, / Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14nfs: nfs4xdr: get rid of WRITE32Benny Halevy
s/WRITE32/*p++ = cpu_to_be32/ Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-14GFS2: Fix permissions on "recover" fileSteven Whitehouse
Although this file is only ever written and not read by userspace, it seems that the utils are opening this file O_RDWR, so we need to allow that. Also fixes the whitespace which seemed to be broken. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> Cc: David Teigland <teigland@redhat.com>
2009-08-13Merge branch 'upstream-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2 * 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2: (22 commits) ocfs2: Fix possible deadlock when extending quota file ocfs2: keep index within status_map[] ocfs2: Initialize the cluster we're writing to in a non-sparse extend ocfs2: Remove redundant BUG_ON in __dlm_queue_ast() ocfs2/quota: Release lock for error in ocfs2_quota_write. ocfs2: Define credit counts for quota operations ocfs2: Remove syncjiff field from quota info ocfs2: Fix initialization of blockcheck stats ocfs2: Zero out padding of on disk dquot structure ocfs2: Initialize blocks allocated to local quota file ocfs2: Mark buffer uptodate before calling ocfs2_journal_access_dq() ocfs2: Make global quota files blocksize aligned ocfs2: Use ocfs2_rec_clusters in ocfs2_adjust_adjacent_records. ocfs2: Fix deadlock on umount ocfs2: Add extra credits and access the modified bh in update_edge_lengths. ocfs2: Fail ocfs2_get_block() immediately when a block needs allocation ocfs2: Fix error return in ocfs2_write_cluster() ocfs2: Fix compilation warning for fs/ocfs2/xattr.c ocfs2: Initialize count in aio_write before generic_write_checks ocfs2: log the actual return value of ocfs2_file_aio_write() ...
2009-08-12Merge branch 'master' of ↵David S. Miller
master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 Conflicts: arch/microblaze/include/asm/socket.h
2009-08-12Merge branch 'for-linus' of git://oss.sgi.com/xfs/xfsLinus Torvalds
* 'for-linus' of git://oss.sgi.com/xfs/xfs: xfs: fix spin_is_locked assert on uni-processor builds xfs: check for dinode realtime flag corruption use XFS_CORRUPTION_ERROR in xfs_btree_check_sblock xfs: switch to NOFS allocation under i_lock in xfs_attr_rmtval_get xfs: switch to NOFS allocation under i_lock in xfs_readlink_bmap xfs: switch to NOFS allocation under i_lock in xfs_attr_rmtval_set xfs: switch to NOFS allocation under i_lock in xfs_buf_associate_memory xfs: switch to NOFS allocation under i_lock in xfs_dir_cilookup_result xfs: switch to NOFS allocation under i_lock in xfs_da_buf_make xfs: switch to NOFS allocation under i_lock in xfs_da_state_alloc xfs: switch to NOFS allocation under i_lock in xfs_getbmap xfs: avoid memory allocation under m_peraglock in growfs code
2009-08-12NFS: Fix an O_DIRECT Oops...Trond Myklebust
We can't call nfs_readdata_release()/nfs_writedata_release() without first initialising and referencing args.context. Doing so inside nfs_direct_read_schedule_segment()/nfs_direct_write_schedule_segment() causes an Oops. We should rather be calling nfs_readdata_free()/nfs_writedata_free() in those cases. Looking at the O_DIRECT code, the "struct nfs_direct_req" is already referencing the nfs_open_context for us. Since the readdata and writedata structures carry a reference to that, we can simplify things by getting rid of the extra nfs_open_context references, so that we can replace all instances of nfs_readdata_release()/nfs_writedata_release(). Reported-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Tested-by: Catalin Marinas <catalin.marinas@arm.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-08-12xfs: fix spin_is_locked assert on uni-processor buildsChristoph Hellwig
Without SMP or preemption spin_is_locked always returns false, so we can't do an assert with it. Instead use assert_spin_locked, which does the right thing on all builds. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Eric Sandeen <sandeen@sandeen.net> Reported-by: Johannes Engel <jcnengel@googlemail.com> Tested-by: Johannes Engel <jcnengel@googlemail.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12xfs: check for dinode realtime flag corruptionChristoph Hellwig
Ramon tested XFS with a modified version of fsfuzzer and hit a NULL pointer dereference in __xfs_get_blocks due to the RT device target pointer being NULL. To fix this reject inode with the realtime bit set on a a filesystem without an RT subvolume during inode read. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Eric Sandeen <sandeen@sandeen.net> Reviewed-by: Felix Blyakher <felixb@sgi.com> Reported-by: Ramon de Carvalho Valle <ramon@risesecurity.org> Tested-by: Ramon de Carvalho Valle <ramon@risesecurity.org> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12use XFS_CORRUPTION_ERROR in xfs_btree_check_sblockEric Sandeen
In Red Hat Bug 512552 - Can't write to XFS mount during raid5 resync a user ran into corruption while resyncing a raid, and we failed a consistency test, but didn't get much more info; it'd be nice to call XFS_CORRUPTION_ERROR here so we can see the buffer contents. Signed-off-by: Eric Sandeen <sandeen@sandeen.net> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12xfs: switch to NOFS allocation under i_lock in xfs_attr_rmtval_getChristoph Hellwig
xfs_attr_rmtval_get is always called with i_lock held, but i_lock is taken in reclaim context so all allocations under it must avoid recursions into the filesystem. Reported by the new reclaim context tracing in lockdep. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Felix Blyakher <felixb@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12xfs: switch to NOFS allocation under i_lock in xfs_readlink_bmapChristoph Hellwig
xfs_readlink_bmap is called with i_lock held, but i_lock is taken in reclaim context so all allocations under it must avoid recursions into the filesystem. Reported by the new reclaim context tracing in lockdep. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Felix Blyakher <felixb@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12xfs: switch to NOFS allocation under i_lock in xfs_attr_rmtval_setChristoph Hellwig
xfs_attr_rmtval_set is always called with i_lock held, and i_lock is taken in reclaim context so all allocations under it must avoid recursions into the filesystem. Reported by the new reclaim context tracing in lockdep. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Felix Blyakher <felixb@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12xfs: switch to NOFS allocation under i_lock in xfs_buf_associate_memoryChristoph Hellwig
xfs_buf_associate_memory is used for setting up the spare buffer for the log wrap case in xlog_sync which can happen under i_lock when called from xfs_fsync. The i_lock mutex is taken in reclaim context so all allocations under it must avoid recursions into the filesystem. There are a couple more uses of xfs_buf_associate_memory in the log recovery code that are also affected by this, but I'd rather keep the code simple than passing on a gfp_mask argument. Longer term we should just stop requiring the memoery allocation in xlog_sync by some smaller rework of the buffer layer. Reported by the new reclaim context tracing in lockdep. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Felix Blyakher <felixb@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12xfs: switch to NOFS allocation under i_lock in xfs_dir_cilookup_resultChristoph Hellwig
xfs_dir_cilookup_result is always called with i_lock held, but i_lock is taken in reclaim context so all allocations under it must avoid recursions into the filesystem. Reported by the new reclaim context tracing in lockdep. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Felix Blyakher <felixb@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12xfs: switch to NOFS allocation under i_lock in xfs_da_buf_makeChristoph Hellwig
i_lock is taken in the reclaim context so all allocations under it must avoid recursions into the filesystem. Reported by the new reclaim context tracing in lockdep. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Felix Blyakher <felixb@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12xfs: switch to NOFS allocation under i_lock in xfs_da_state_allocChristoph Hellwig
xfs_da_state_alloc is always called with i_lock held, but i_lock is taken in reclaim context so all allocations under it must avoid recursions into the filesystem. Reported by the new reclaim context tracing in lockdep. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Felix Blyakher <felixb@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12xfs: switch to NOFS allocation under i_lock in xfs_getbmapChristoph Hellwig
xfs_getbmap allocates memory with i_lock held, but i_lock is taken in reclaim context so all allocations under it must avoid recursions into the filesystem. Reported by the new reclaim context tracing in lockdep. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Felix Blyakher <felixb@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-12xfs: avoid memory allocation under m_peraglock in growfs codeChristoph Hellwig
Allocate the memory for the larger m_perag array before taking the per-AG lock as the per-AG lock can be taken under the i_lock which can be taken from reclaim context. Reported by the new reclaim context tracing in lockdep. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Felix Blyakher <felixb@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
2009-08-11Merge branch 'master' into nextJames Morris
2009-08-10Merge branch 'sunrpc_cache-for-2.6.32' into nfs-for-2.6.32Trond Myklebust
2009-08-10Merge branch 'patches_cel-for-2.6.32' into nfs-for-2.6.32Trond Myklebust
2009-08-10ocfs2: Fix possible deadlock when extending quota fileJan Kara
In OCFS2, allocator locks rank above transaction start. Thus we cannot extend quota file from inside a transaction less we could deadlock. We solve the problem by starting transaction not already in ocfs2_acquire_dquot() but only in ocfs2_local_read_dquot() and ocfs2_global_read_dquot() and we allocate blocks to quota files before starting the transaction. In case we crash, quota files will just have a few blocks more but that's no problem since we just use them next time we extend the quota file. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Joel Becker <joel.becker@oracle.com>
2009-08-10nfs: remove superfluous BUG_ON()sBartlomiej Zolnierkiewicz
Subject: [PATCH] nfs: remove superfluous BUG_ON()s Remove duplicated BUG_ON()s from nfs[4]_create_server() (we make the same checks earlier in both functions). This takes care of the following entries from Dan's list: fs/nfs/client.c +1078 nfs_create_server(47) warning: variable derefenced before check 'server->nfs_client' fs/nfs/client.c +1079 nfs_create_server(48) warning: variable derefenced before check 'server->nfs_client->rpc_ops' fs/nfs/client.c +1363 nfs4_create_server(43) warning: variable derefenced before check 'server->nfs_client' fs/nfs/client.c +1364 nfs4_create_server(44) warning: variable derefenced before check 'server->nfs_ Reported-by: Dan Carpenter <error27@gmail.com> Cc: corbet@lwn.net Cc: eteo@redhat.com Cc: Julia Lawall <julia@diku.dk> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-10NFS: read-modify-write page updatingPeter Staubach
Hi. I have a proposal for possibly resolving this issue. I believe that this situation occurs due to the way that the Linux NFS client handles writes which modify partial pages. The Linux NFS client handles partial page modifications by allocating a page from the page cache, copying the data from the user level into the page, and then keeping track of the offset and length of the modified portions of the page. The page is not marked as up to date because there are portions of the page which do not contain valid file contents. When a read call comes in for a portion of the page, the contents of the page must be read in the from the server. However, since the page may already contain some modified data, that modified data must be written to the server before the file contents can be read back in the from server. And, since the writing and reading can not be done atomically, the data must be written and committed to stable storage on the server for safety purposes. This means either a FILE_SYNC WRITE or a UNSTABLE WRITE followed by a COMMIT. This has been discussed at length previously. This algorithm could be described as modify-write-read. It is most efficient when the application only updates pages and does not read them. My proposed solution is to add a heuristic to decide whether to do this modify-write-read algorithm or switch to a read- modify-write algorithm when initially allocating the page in the write system call path. The heuristic uses the modes that the file was opened with, the offset in the page to read from, and the size of the region to read. If the file was opened for reading in addition to writing and the page would not be filled completely with data from the user level, then read in the old contents of the page and mark it as Uptodate before copying in the new data. If the page would be completely filled with data from the user level, then there would be no reason to read in the old contents because they would just be copied over. This would optimize for applications which randomly access and update portions of files. The linkage editor for the C compiler is an example of such a thing. I tested the attached patch by using rpmbuild to build the current Fedora rawhide kernel. The kernel without the patch generated about 269,500 WRITE requests. The modified kernel containing the patch generated about 261,000 WRITE requests. Thus, about 8,500 fewer WRITE requests were generated. I suspect that many of these additional WRITE requests were probably FILE_SYNC requests to WRITE a single page, but I didn't test this theory. The difference between this patch and the previous one was to remove the unneeded PageDirty() test. I then retested to ensure that the resulting system continued to behave as desired. Thanx... ps Signed-off-by: Peter Staubach <staubach@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-10NFS: Add a ->migratepage() aop for NFSTrond Myklebust
Make NFS a bit more friendly to NUMA and memory hot removal... Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-08-10chrdev: implement __[un]register_chrdev()Tejun Heo
[un]register_chrdev() assume minor range 0-255. This patch adds __ prefixed versions which take @minorbase and @count explicitly. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
2009-08-10mm_for_maps: take ->cred_guard_mutex to fix the race with execOleg Nesterov
The problem is minor, but without ->cred_guard_mutex held we can race with exec() and get the new ->mm but check old creds. Now we do not need to re-check task->mm after ptrace_may_access(), it can't be changed to the new mm under us. Strictly speaking, this also fixes another very minor problem. Unless security check fails or the task exits mm_for_maps() should never return NULL, the caller should get either old or new ->mm. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
2009-08-10mm_for_maps: shift down_read(mmap_sem) to the callerOleg Nesterov
mm_for_maps() takes ->mmap_sem after security checks, this looks strange and obfuscates the locking rules. Move this lock to its single caller, m_start(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>