This is (again) a preparatory patch similar to commit
a2a9537ac0. It open codes a simple
async way of executing do_thaw_all() out of context, so we can get
rid of pdflush.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
fuse: fix "direct_io" private mmap
fuse: fix argument type in fuse_get_user_pages()
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2:
nilfs2: fix possible mismatch of sufile counters on recovery
nilfs2: segment usage file cleanups
nilfs2: fix wrong accounting and duplicate brelse in nilfs_sufile_set_error
nilfs2: simplify handling of active state of segments fix
nilfs2: remove module version
nilfs2: fix lockdep recursive locking warning on meta data files
nilfs2: fix lockdep recursive locking warning on bmap
nilfs2: return f_fsid for statfs2
If two writers allocating blocks to file race with each other (e.g.
because writepages races with ordinary write or two writepages race with
each other), ext2_getblock() can be called on the same inode in parallel.
Before we are going to allocate new blocks, we have to recheck the block
chain we have obtained so far without holding truncate_mutex. Otherwise
we could overwrite the indirect block pointer set by the other writer
leading to data loss.
The below test program by Ying is able to reproduce the data loss with ext2
on in BRD in a few minutes if the machine is under memory pressure:
long kMemSize = 50 << 20;
int kPageSize = 4096;
int main(int argc, char **argv) {
int status;
int count = 0;
int i;
char *fname = "/mnt/test.mmap";
char *mem;
unlink(fname);
int fd = open(fname, O_CREAT | O_EXCL | O_RDWR, 0600);
status = ftruncate(fd, kMemSize);
mem = mmap(0, kMemSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
// Fill the memory with 1s.
memset(mem, 1, kMemSize);
sleep(2);
for (i = 0; i < kMemSize; i++) {
int byte_good = mem[i] != 0;
if (!byte_good && ((i % kPageSize) == 0)) {
//printf("%d ", i / kPageSize);
count++;
}
}
munmap(mem, kMemSize);
close(fd);
unlink(fname);
if (count > 0) {
printf("Running %d bad page\n", count);
return 1;
}
return 0;
}
Cc: Ying Han <yinghan@google.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Update information about locking in JBD revoke code.
Reported-by: Lin Tan <tammy000@gmail.com>.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When an HFS filesystem is unmounted, it leaks a 2-page bitmap. Also,
under extreme memory pressure, it's possible that hfs_releasepage() may
use a tree pointer that has not been initialized, and if so, the release
request should just be rejected.
[akpm@linux-foundation.org: free_pages(0) is legal, remove obvious comment]
Signed-off-by: Dave Anderson <anderson@redhat.com>
Tested-by: Eugene Teo <eugeneteo@kernel.sg>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://oss.sgi.com/xfs/xfs:
xfs: remove xfs_flush_space
xfs: flush delayed allcoation blocks on ENOSPC in create
xfs: block callers of xfs_flush_inodes() correctly
xfs: make inode flush at ENOSPC synchronous
xfs: use xfs_sync_inodes() for device flushing
xfs: inform the xfsaild of the push target before sleeping
xfs: prevent unwritten extent conversion from blocking I/O completion
xfs: fix double free of inode
xfs: validate log feature fields correctly
On-disk counters ndirtysegs and ncleansegs of sufile, can go wrong
after roll-forward recovery because
nilfs_prepare_segment_for_recovery() function marks segments dirty
without adjusting value of these counters.
This fixes the problem by adding a function to sufile which does the
operation adjusting the counters, and by letting the recovery function
use it.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This will simplify sufile.c by sharing common code which repeatedly
appears in routines updating a segment usage entry; a wrapper function
nilfs_sufile_update() is introduced for the purpose, and counter
modifications are integrated to a new function
nilfs_sufile_mod_counter().
This is a preparation for the successive bugfix patch ("nilfs2: fix
possible mismatch of sufile counters on recovery").
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
The nilfs_sufile_set_error() function wrongly adjusts the number of
dirty segments instead of the number of clean segments. In addition,
the function calls brelse() twice for the same buffer head.
This fixes these bugs.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This fixes a bug of ("nilfs2: simplify handling of active state of
segments") patch. The patch did not take account that a base index is
increased in nilfs_sufile_get_suinfo() function if requested entries
go across block boundary on sufile.
Due to this bug, the active flag sometimes appears on wrong segments
and has induced malfunction of garbage collection.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
A MODULE_VERSION() macro has been used in out-of-tree nilfs modules,
but it's needless and not updated in tree. So, this removes it along
with the version declaration.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This fixes the following false detection of lockdep against nilfs meta
data files:
=============================================
[ INFO: possible recursive locking detected ]
2.6.29 #26
---------------------------------------------
mount.nilfs2/4185 is trying to acquire lock:
(&mi->mi_sem){----}, at: [<d0c7925b>] nilfs_sufile_get_stat+0x1e/0x105 [nilfs2]
but task is already holding lock:
(&mi->mi_sem){----}, at: [<d0c72026>] nilfs_count_free_blocks+0x48/0x84 [nilfs2]
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
The bmap semaphore of DAT file can be held while a bmap of other files
is locked. This has caused the following false detection of lockdep
check:
mount.nilfs2/4667 is trying to acquire lock:
(&bmap->b_sem){..--}, at: [<d0c6c4b4>] nilfs_bmap_lookup_at_level+0x1a/0x74 [nilfs2]
but task is already holding lock:
(&bmap->b_sem){..--}, at: [<d0c6c4b4>] nilfs_bmap_lookup_at_level+0x1a/0x74 [nilfs2]
This will fix the false detection by distinguishing semaphores of the
DAT and other files.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This follows the change of Coly Li's series ("fs: return f_fsid for
statfs(2)"), and make nilfs2 return f_fsid info for statfs(2).
Acked-by: Coly Li <coly.li@suse.de>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: check block device size on mount
ext4: Fix off-by-one-error in ext4_valid_extent_idx()
ext4: Fix big-endian problem in __ext4_check_blockref()
MAP_PRIVATE mmap could return stale data from the cache for
"direct_io" files. Fix this by flushing the cache on mmap.
Found with a slightly modified fsx-linux.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Fix the following warning:
fs/fuse/file.c: In function 'fuse_direct_io':
fs/fuse/file.c:1002: warning: passing argument 3 of 'fuse_get_user_pages' from incompatible pointer type
This was introduced by commit f4975c67 "fuse: allow kernel to access
"direct_io" files".
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
* 'ext3-latency-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext3: Try to avoid starting a transaction in writepage for data=writepage
block_write_full_page: switch synchronous writes to use WRITE_SYNC_PLUG
6260a4b052 ("/proc/pid/maps: don't show
pgoff of pure ANON VMAs" had a typo.
fs/proc/task_nommu.c:138: error: 'struct vm_area_struct' has no member named 'pg_off'
distcc[21484] ERROR: compile fs/proc/task_nommu.c on sprygo/32 failed
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This does the same as commit 9e80d40773
(avoid starting a transaction when no block allocation is needed)
but for data=writeback mode of ext3. We also cleanup the data=ordered
case a bit to stick to coding style...
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Now that we have a distinction between WRITE_SYNC and WRITE_SYNC_PLUG,
use WRITE_SYNC_PLUG in __block_write_full_page() to avoid unplugging
the block device I/O queue between each page that gets flushed out.
Otherwise, when we run sync() or fsync() and we need to write out a
large number of pages, the block device queue will get unplugged
between for every page that is flushed out, which will be a pretty
serious performance regression caused by commit a64c8610.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Commit c2ec175c39 ("mm: page_mkwrite
change prototype to match fault") exposed a bug in the NFS
implementation of page_mkwrite. We should be returning 0 on success...
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's a possible deadlock in generic_file_splice_write(),
splice_from_pipe() and ocfs2_file_splice_write():
- task A calls generic_file_splice_write()
- this calls inode_double_lock(), which locks i_mutex on both
pipe->inode and target inode
- ordering depends on inode pointers, can happen that pipe->inode is
locked first
- __splice_from_pipe() needs more data, calls pipe_wait()
- this releases lock on pipe->inode, goes to interruptible sleep
- task B calls generic_file_splice_write(), similarly to the first
- this locks pipe->inode, then tries to lock inode, but that is
already held by task A
- task A is interrupted, it tries to lock pipe->inode, but fails, as
it is already held by task B
- ABBA deadlock
Fix this by explicitly ordering locks: the outer lock must be on
target inode and the inner lock (which is later unlocked and relocked)
must be on pipe->inode. This is OK, pipe inodes and target inodes
form two nonoverlapping sets, generic_file_splice_write() and friends
are not called with a target which is a pipe.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Mark Fasheh <mfasheh@suse.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After a review of user's feedback for finding out other compatibility
issues, I found nilfs improperly initializes timestamps in inode;
CURRENT_TIME was used there instead of CURRENT_TIME_SEC even though nilfs
didn't have nanosecond timestamps on disk. A few users gave us the report
that the tar program sometimes failed to expand symbolic links on nilfs,
and it turned out to be the cause.
Instead of applying the above displacement, I've decided to support
nanosecond timestamps on this occation. Fortunetaly, a needless 64-bit
field was in the nilfs_inode struct, and I found it's available for this
purpose without impact for the users.
So, this will do the enhancement and resolve the tar problem.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The former versions didn't have extra super blocks. This improves the
weak point by introducing another super block at unused region in tail of
the partition.
This doesn't break disk format compatibility; older versions just ingore
the secondary super block, and new versions just recover it if it doesn't
exist. The partition created by an old mkfs may not have unused region,
but in that case, the secondary super block will not be added.
This doesn't make more redundant copies of the super block; it is a future
work.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
will reduce some lines of segment constructor. Previously, the state was
complexly controlled through a list of segments in order to keep
consistency in meta data of usage state of segments. Instead, this
presents ``calculated'' active flags to userland cleaner program and stop
maintaining its real flag on disk.
Only by this fake flag, the cleaner cannot exactly know if each segment is
reclaimable or not. However, the recent extension of nilfs_sustat ioctl
struct (nilfs2-extend-nilfs_sustat-ioctl-struct.patch) can prevent the
cleaner from reclaiming in-use segment wrongly.
So, now I can apply this for simplification.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nilfs creates checkpoints even for garbage collection or metadata updates
such as checkpoint mode change. So, user often sees checkpoints created
only by such internal operations.
This is inconvenient in some situations. For example, application that
monitors checkpoints and changes them to snapshots, will fall into an
infinite loop because it cannot distinguish internally created
checkpoints.
This patch solves this sort of problem by adding a flag to checkpoint for
identification.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The sketch file is a file to mark checkpoints with user data. It was
experimentally introduced in the original implementation, and now
obsolete. The file was handled differently with regular files; the file
size got truncated when a checkpoint was created.
This stops the special treatment and will treat it as a regular file.
Most users are not affected because mkfs.nilfs2 no longer makes this file.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adds a missing endian conversion of checksum field in the super
block. This fixes compatibility issue on big endian machines which will
come to surface after supporting recovery of super block.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pekka Enberg advised me:
> It would be nice if BUG(), BUG_ON(), and panic() calls would be
> converted to proper error handling using WARN_ON() calls. The BUG()
> call in nilfs_cpfile_delete_checkpoints(), for example, looks to be
> triggerable from user-space via the ioctl() system call.
This will follow the comment and keep them to a minimum.
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adds a new argument to the nilfs_sustat structure.
The extended field allows to delete volatile active state of segments,
which was needed to protect freshly-created segments from garbage
collection but has confused code dealing with segments. This
extension alleviates the mess and gives room for further
simplifications.
The volatile active flag is not persistent, so it's eliminable on this
occasion without affecting compatibility other than the ioctl change.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pekka Enberg suggested converting ->ioctl operations to use
->unlocked_ioctl to avoid BKL.
The conversion was verified to be safe, so I will take it on this
occasion.
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This removes compat code from the nilfs ioctls and applies the same
function for both .ioctl and .compat_ioctl file operations.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nilfs ioctl had structures not having fixed sized types such as:
struct nilfs_argv {
void *v_base;
size_t v_nmembs;
size_t v_size;
int v_index;
int v_flags;
};
Further, some of them are wrongly aligned:
e.g.
struct nilfs_cpmode {
__u64 cm_cno;
int cm_mode;
};
The size of wrongly aligned structures varies depending on
architectures, and it breaks the identity of ioctl commands, which
leads to arch dependent errors.
Previously, these are compensated by using compat_ioctl.
This fixes these problems and allows removal of compat ioctl.
Since this will change sizes of those structures, binary compatibility
for the past utilities will once break; new utilities have to be used
instead. However, it would be helpful to avoid platform dependent
problems in the long term.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This removes NILFS_IOCTL_TIMEDWAIT command from ioctl interface along
with the related flags and wait queue.
The command is terrible because it just sleeps in the ioctl. I prefer
to avoid this by devising means of event polling in userland program.
By reconsidering the userland GC daemon, I found this is possible
without changing behaviour of the daemon and sacrificing efficiency.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This will fix the weird behavior of lscp command in listing continuously
created checkpoints; the output of lscp is rewinded regularly for the
recent nilfs. As a result of debugging, a defect was found in
nilfs_cpfile_do_get_cpinfo() function.
Though the function can be repeatedly called to enumerate checkpoints and
it can skip invalid checkpoint entries, the index value was not carried
between successive calls.
The bug has long been present, and came to surface after applying a bugfix
nilfs2-fix-problems-of-memory-allocation-in-ioctl.patch, which increased
frequency of calling the function. The similar bugfix was already applied
for ``snapshots'' by
nilfs2-fix-gc-failure-on-volumes-keeping-numerous-snapshots.patch.
This fixes the problem by making the index argument bidirectional on the
function.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This cleans up the strange indirect function calling convention used in
nilfs to follow the normal kernel coding style.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A few tool developers gave me requests for fixing inconvenient return
value of nilfs_get_cpinfo() ioctl; if the requested mode is NILFS_SNAPSHOT
and the specified start entry is not a snapshot, the ioctl unnaturally
returns one as the number of acquired snapshot item.
In addition, the ioctl function returns an ENOENT error for checkpoints
within blocks deleted by garbage collection.
These behaviors require corrections for programs which enumerate
snapshots. This resolves the inconvenience by changing the return values
to zero for the above cases.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This resolves the following failure of nilfs2 cleaner daemon:
nilfs_cleanerd[20670]: cannot clean segments: No such file or directory
nilfs_cleanerd[20670]: shutdown
When creating thousands of snapshots, the cleaner daemon had rarely died
as above due to an error returned from the kernel code.
After applying the recent patch which fixed memory allocation problems in
ioctl (Message-Id: <20081215.155840.105124170.ryusuke@osrg.net>), the
problem gets more frequent.
It turned out to be a bug of nilfs_ioctl_wrap_copy function and one of its
callback routines to read out information of snapshots; if the
nilfs_ioctl_wrap_copy function divided a large read request into multiple
requests, the second and later requests have failed since a restart
position on snapshot meta data was not properly set forward.
It's a deficiency of the callback interface that cannot pass the restart
position among multiple requests. This patch fixes the issue by allowing
nilfs_ioctl_wrap_copy and snapshot read functions to exchange a position
argument.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The file gcinode.c gives buffer cache functions for on-disk blocks
moved in garbage collection. Joern Engel has suggested inserting its
explanations in the source file (Message-ID:
<20080917144146.GD8750@logfs.org> and
<20080917224953.GB14644@logfs.org>).
This follows the comment.
Cc: Joern Engel <joern@logfs.org>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pekka Enberg pointed out that double error handlings found after
nilfs_transaction_end() can be avoided by separating abort operation:
OK, I don't understand this. The only way nilfs_transaction_end() can
fail is if we have NILFS_TI_SYNC set and we fail to construct the
segment. But why do we want to construct a segment if we don't commit?
I guess what I'm asking is why don't we have a separate
nilfs_transaction_abort() function that can't fail for the erroneous
case to avoid this double error value tracking thing?
This does the separation and renames nilfs_transaction_end() to
nilfs_transaction_commit() for clarification.
Since, some calls of these functions were used just for exclusion control
against the segment constructor, they are replaced with semaphore
operations.
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This will remove the following unnecessary locks and cleanup code in
nilfs_clear_inode():
- unnecessary protection using nilfs_transaction_begin() and
nilfs_transaction_end().
- cleanup code of i_dirty list field which is never chained
when this function is called.
- spinlock used when releasing i_bh field.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is another patch for fixing the following problems of a memory
copy function in nilfs2 ioctl:
(1) It tries to allocate 128KB size of memory even for small objects.
(2) Though the function repeatedly tries large memory allocations
while reducing the size, GFP_NOWAIT flag is not specified.
This increases the possibility of system memory shortage.
(3) During the retries of (2), verbose warnings are printed
because _GFP_NOWARN flag is not used for the kmalloc calls.
The first patch was still doing large allocations by kmalloc which are
repeatedly tried while reducing the size.
Andi Kleen told me that using copy_from_user for large memory is not
good from the viewpoint of preempt latency:
On Fri, 12 Dec 2008 21:24:11 +0100, Andi Kleen <andi@firstfloor.org> wrote:
> > In the current interface, each data item is copied twice: one is to
> > the allocated memory from user space (via copy_from_user), and another
>
> For such large copies it is better to use multiple smaller (e.g. 4K)
> copy user, that gives better real time preempt latencies. Each cfu has a
> cond_resched(), but only one, not multiple times in the inner loop.
He also advised me that:
On Sun, 14 Dec 2008 16:13:27 +0100, Andi Kleen <andi@firstfloor.org> wrote:
> Better would be if you could go to PAGE_SIZE. order 0 allocations
> are typically the fastest / least likely to stall.
>
> Also in this case it's a good idea to use __get_free_pages()
> directly, kmalloc tends to be become less efficient at larger
> sizes.
For the function in question, the size of buffer memory can be reduced
since the buffer is repeatedly used for a number of small objects. On
the other hand, it may incur large preempt latencies for larger buffer
because a copy_from_user (and a copy_to_user) was applied only once
each cycle.
With that, this revision uses the order 0 allocations with
__get_free_pages() to fix the original problems.
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adds a Makefile for the nilfs2 file system, and updates the
makefile and Kconfig file in the file system directory.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adds userland interface implemented with ioctl.
Signed-off-by: Koji Sato <sato.koji@lab.ntt.co.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
