20 Jul, 2007
4 commits
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Slab destructors were no longer supported after Christoph's
c59def9f222d44bb7e2f0a559f2906191a0862d7 change. They've been
BUGs for both slab and slub, and slob never supported them
either.This rips out support for the dtor pointer from kmem_cache_create()
completely and fixes up every single callsite in the kernel (there were
about 224, not including the slab allocator definitions themselves,
or the documentation references).Signed-off-by: Paul Mundt
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Change ->fault prototype. We now return an int, which contains
VM_FAULT_xxx code in the low byte, and FAULT_RET_xxx code in the next byte.
FAULT_RET_ code tells the VM whether a page was found, whether it has been
locked, and potentially other things. This is not quite the way he wanted
it yet, but that's changed in the next patch (which requires changes to
arch code).This means we no longer set VM_CAN_INVALIDATE in the vma in order to say
that a page is locked which requires filemap_nopage to go away (because we
can no longer remain backward compatible without that flag), but we were
going to do that anyway.struct fault_data is renamed to struct vm_fault as Linus asked. address
is now a void __user * that we should firmly encourage drivers not to use
without really good reason.The page is now returned via a page pointer in the vm_fault struct.
Signed-off-by: Nick Piggin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Nonlinear mappings are (AFAIKS) simply a virtual memory concept that encodes
the virtual address -> file offset differently from linear mappings.->populate is a layering violation because the filesystem/pagecache code
should need to know anything about the virtual memory mapping. The hitch here
is that the ->nopage handler didn't pass down enough information (ie. pgoff).
But it is more logical to pass pgoff rather than have the ->nopage function
calculate it itself anyway (because that's a similar layering violation).Having the populate handler install the pte itself is likewise a nasty thing
to be doing.This patch introduces a new fault handler that replaces ->nopage and
->populate and (later) ->nopfn. Most of the old mechanism is still in place
so there is a lot of duplication and nice cleanups that can be removed if
everyone switches over.The rationale for doing this in the first place is that nonlinear mappings are
subject to the pagefault vs invalidate/truncate race too, and it seemed stupid
to duplicate the synchronisation logic rather than just consolidate the two.After this patch, MAP_NONBLOCK no longer sets up ptes for pages present in
pagecache. Seems like a fringe functionality anyway.NOPAGE_REFAULT is removed. This should be implemented with ->fault, and no
users have hit mainline yet.[akpm@linux-foundation.org: cleanup]
[randy.dunlap@oracle.com: doc. fixes for readahead]
[akpm@linux-foundation.org: build fix]
Signed-off-by: Nick Piggin
Signed-off-by: Randy Dunlap
Cc: Mark Fasheh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix the race between invalidate_inode_pages and do_no_page.
Andrea Arcangeli identified a subtle race between invalidation of pages from
pagecache with userspace mappings, and do_no_page.The issue is that invalidation has to shoot down all mappings to the page,
before it can be discarded from the pagecache. Between shooting down ptes to
a particular page, and actually dropping the struct page from the pagecache,
do_no_page from any process might fault on that page and establish a new
mapping to the page just before it gets discarded from the pagecache.The most common case where such invalidation is used is in file truncation.
This case was catered for by doing a sort of open-coded seqlock between the
file's i_size, and its truncate_count.Truncation will decrease i_size, then increment truncate_count before
unmapping userspace pages; do_no_page will read truncate_count, then find the
page if it is within i_size, and then check truncate_count under the page
table lock and back out and retry if it had subsequently been changed (ptl
will serialise against unmapping, and ensure a potentially updated
truncate_count is actually visible).Complexity and documentation issues aside, the locking protocol fails in the
case where we would like to invalidate pagecache inside i_size. do_no_page
can come in anytime and filemap_nopage is not aware of the invalidation in
progress (as it is when it is outside i_size). The end result is that
dangling (->mapping == NULL) pages that appear to be from a particular file
may be mapped into userspace with nonsense data. Valid mappings to the same
place will see a different page.Andrea implemented two working fixes, one using a real seqlock, another using
a page->flags bit. He also proposed using the page lock in do_no_page, but
that was initially considered too heavyweight. However, it is not a global or
per-file lock, and the page cacheline is modified in do_no_page to increment
_count and _mapcount anyway, so a further modification should not be a large
performance hit. Scalability is not an issue.This patch implements this latter approach. ->nopage implementations return
with the page locked if it is possible for their underlying file to be
invalidated (in that case, they must set a special vm_flags bit to indicate
so). do_no_page only unlocks the page after setting up the mapping
completely. invalidation is excluded because it holds the page lock during
invalidation of each page (and ensures that the page is not mapped while
holding the lock).This also allows significant simplifications in do_no_page, because we have
the page locked in the right place in the pagecache from the start.Signed-off-by: Nick Piggin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Jul, 2007
1 commit
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Some users have been having problems with utilities like cp or dd dumping
core when they try to copy a file that's too large for the destination
filesystem (typically, > 4gb). Apparently, some defunct standards required
SIGXFSZ to be sent in such circumstances, but SUS only requires/allows it
for when a written file exceeds the process's resource limits. I'd like to
limit SIGXFSZs to the bare minimum required by SUS.Patch sent per http://lkml.org/lkml/2007/4/10/302
Signed-off-by: Micah Cowan
Acked-by: Alan Cox
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
22 May, 2007
1 commit
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First thing mm.h does is including sched.h solely for can_do_mlock() inline
function which has "current" dereference inside. By dealing with can_do_mlock()
mm.h can be detached from sched.h which is good. See below, why.This patch
a) removes unconditional inclusion of sched.h from mm.h
b) makes can_do_mlock() normal function in mm/mlock.c
c) exports can_do_mlock() to not break compilation
d) adds sched.h inclusions back to files that were getting it indirectly.
e) adds less bloated headers to some files (asm/signal.h, jiffies.h) that were
getting them indirectlyNet result is:
a) mm.h users would get less code to open, read, preprocess, parse, ... if
they don't need sched.h
b) sched.h stops being dependency for significant number of files:
on x86_64 allmodconfig touching sched.h results in recompile of 4083 files,
after patch it's only 3744 (-8.3%).Cross-compile tested on
all arm defconfigs, all mips defconfigs, all powerpc defconfigs,
alpha alpha-up
arm
i386 i386-up i386-defconfig i386-allnoconfig
ia64 ia64-up
m68k
mips
parisc parisc-up
powerpc powerpc-up
s390 s390-up
sparc sparc-up
sparc64 sparc64-up
um-x86_64
x86_64 x86_64-up x86_64-defconfig x86_64-allnoconfigas well as my two usual configs.
Signed-off-by: Alexey Dobriyan
Signed-off-by: Linus Torvalds
17 May, 2007
1 commit
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SLAB_CTOR_CONSTRUCTOR is always specified. No point in checking it.
Signed-off-by: Christoph Lameter
Cc: David Howells
Cc: Jens Axboe
Cc: Steven French
Cc: Michael Halcrow
Cc: OGAWA Hirofumi
Cc: Miklos Szeredi
Cc: Steven Whitehouse
Cc: Roman Zippel
Cc: David Woodhouse
Cc: Dave Kleikamp
Cc: Trond Myklebust
Cc: "J. Bruce Fields"
Cc: Anton Altaparmakov
Cc: Mark Fasheh
Cc: Paul Mackerras
Cc: Christoph Hellwig
Cc: Jan Kara
Cc: David Chinner
Cc: "David S. Miller"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 May, 2007
1 commit
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Remove includes of where it is not used/needed.
Suggested by Al Viro.Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).Signed-off-by: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
08 May, 2007
1 commit
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I have never seen a use of SLAB_DEBUG_INITIAL. It is only supported by
SLAB.I think its purpose was to have a callback after an object has been freed
to verify that the state is the constructor state again? The callback is
performed before each freeing of an object.I would think that it is much easier to check the object state manually
before the free. That also places the check near the code object
manipulation of the object.Also the SLAB_DEBUG_INITIAL callback is only performed if the kernel was
compiled with SLAB debugging on. If there would be code in a constructor
handling SLAB_DEBUG_INITIAL then it would have to be conditional on
SLAB_DEBUG otherwise it would just be dead code. But there is no such code
in the kernel. I think SLUB_DEBUG_INITIAL is too problematic to make real
use of, difficult to understand and there are easier ways to accomplish the
same effect (i.e. add debug code before kfree).There is a related flag SLAB_CTOR_VERIFY that is frequently checked to be
clear in fs inode caches. Remove the pointless checks (they would even be
pointless without removeal of SLAB_DEBUG_INITIAL) from the fs constructors.This is the last slab flag that SLUB did not support. Remove the check for
unimplemented flags from SLUB.Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Mar, 2007
1 commit
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Use internal buffers instead of the ones supplied by the caller
so that a caller can be interrupted without having to abort the
entire ncp connection.Signed-off-by: Pierre Ossman
Acked-by: Petr Vandrovec
13 Feb, 2007
2 commits
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This patch is inspired by Arjan's "Patch series to mark struct
file_operations and struct inode_operations const".Compile tested with gcc & sparse.
Signed-off-by: Josef 'Jeff' Sipek
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Many struct inode_operations in the kernel can be "const". Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data. In addition it'll catch accidental writes at compile time to
these shared resources.Signed-off-by: Arjan van de Ven
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Dec, 2006
2 commits
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This took a little refactoring but now errors are handled cleanly. When
this code used pid_t values this wasn't necessary because you can't
leak a pid_t.Thanks to Peter Vandrovec for spotting this.
Signed-off-by: Eric W. Biederman
Cc: Peter Vandrovec
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This patch converts the tracking of the user space watchdog process from using
a pid_t to use struct pid. This makes us safe from pid wrap around issues and
prepares the way for the pid namespace.Signed-off-by: Eric W. Biederman
Cc: Petr Vandrovec
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 Dec, 2006
1 commit
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Signed-off-by: Josef Sipek
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
08 Dec, 2006
2 commits
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Replace all uses of kmem_cache_t with struct kmem_cache.
The patch was generated using the following script:
#!/bin/sh
#
# Replace one string by another in all the kernel sources.
#set -e
for file in `find * -name "*.c" -o -name "*.h"|xargs grep -l $1`; do
quilt add $file
sed -e "1,\$s/$1/$2/g" $file >/tmp/$$
mv /tmp/$$ $file
quilt refresh
doneThe script was run like this
sh replace kmem_cache_t "struct kmem_cache"
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
SLAB_KERNEL is an alias of GFP_KERNEL.
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
22 Nov, 2006
1 commit
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Fix up for make allyesconfig.
Signed-Off-By: David Howells
10 Oct, 2006
1 commit
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Signed-off-by: Al Viro
Signed-off-by: Linus Torvalds
01 Oct, 2006
1 commit
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The ncp specific compat ioctls are clearly local to one file system, so the
code can better live there.This version of the patch moves everything into the generic ioctl handler
and uses it for both 32 and 64 bit calls.Signed-off-by: Arnd Bergmann
Signed-off-by: Petr Vandrovec
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
27 Sep, 2006
4 commits
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This eliminates the i_blksize field from struct inode. Filesystems that want
to provide a per-inode st_blksize can do so by providing their own getattr
routine instead of using the generic_fillattr() function.Note that some filesystems were providing pretty much random (and incorrect)
values for i_blksize.[bunk@stusta.de: cleanup]
[akpm@osdl.org: generic_fillattr() fix]
Signed-off-by: "Theodore Ts'o"
Signed-off-by: Adrian Bunk
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
* Rougly half of callers already do it by not checking return value
* Code in drivers/acpi/osl.c does the following to be sure:(void)kmem_cache_destroy(cache);
* Those who check it printk something, however, slab_error already printed
the name of failed cache.
* XFS BUGs on failed kmem_cache_destroy which is not the decision
low-level filesystem driver should make. Converted to ignore.Signed-off-by: Alexey Dobriyan
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
* Removing useless casts
* Removing useless wrapper
* Conversion from kmalloc+memset to kzallocSigned-off-by: Panagiotis Issaris
Acked-by: Dave Kleikamp
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Conversions from kmalloc+memset to kzalloc.
Signed-off-by: Panagiotis Issaris
Jffs2-bit-acked-by: David Woodhouse
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 Jul, 2006
3 commits
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* git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial:
Remove obsolete #include
remove obsolete swsusp_encrypt
arch/arm26/Kconfig typos
Documentation/IPMI typos
Kconfig: Typos in net/sched/Kconfig
v9fs: do not include linux/version.h
Documentation/DocBook/mtdnand.tmpl: typo fixes
typo fixes: specfic -> specific
typo fixes in Documentation/networking/pktgen.txt
typo fixes: occuring -> occurring
typo fixes: infomation -> information
typo fixes: disadvantadge -> disadvantage
typo fixes: aquire -> acquire
typo fixes: mecanism -> mechanism
typo fixes: bandwith -> bandwidth
fix a typo in the RTC_CLASS help text
smb is no longer maintainedManually merged trivial conflict in arch/um/kernel/vmlinux.lds.S
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The remaining counters in page_state after the zoned VM counter patches
have been applied are all just for show in /proc/vmstat. They have no
essential function for the VM.We use a simple increment of per cpu variables. In order to avoid the most
severe races we disable preempt. Preempt does not prevent the race between
an increment and an interrupt handler incrementing the same statistics
counter. However, that race is exceedingly rare, we may only loose one
increment or so and there is no requirement (at least not in kernel) that
the vm event counters have to be accurate.In the non preempt case this results in a simple increment for each
counter. For many architectures this will be reduced by the compiler to a
single instruction. This single instruction is atomic for i386 and x86_64.
And therefore even the rare race condition in an interrupt is avoided for
both architectures in most cases.The patchset also adds an off switch for embedded systems that allows a
building of linux kernels without these counters.The implementation of these counters is through inline code that hopefully
results in only a single instruction increment instruction being emitted
(i386, x86_64) or in the increment being hidden though instruction
concurrency (EPIC architectures such as ia64 can get that done).Benefits:
- VM event counter operations usually reduce to a single inline instruction
on i386 and x86_64.
- No interrupt disable, only preempt disable for the preempt case.
Preempt disable can also be avoided by moving the counter into a spinlock.
- Handling is similar to zoned VM counters.
- Simple and easily extendable.
- Can be omitted to reduce memory use for embedded use.References:
RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=113512330605497&w=2
RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=114988082814934&w=2
local_t http://marc.theaimsgroup.com/?l=linux-kernel&m=114991748606690&w=2
V2 http://marc.theaimsgroup.com/?t=115014808400007&r=1&w=2
V3 http://marc.theaimsgroup.com/?l=linux-kernel&m=115024767022346&w=2
V4 http://marc.theaimsgroup.com/?l=linux-kernel&m=115047968808926&w=2Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Signed-off-by: Jörn Engel
Signed-off-by: Adrian Bunk
29 Jun, 2006
1 commit
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Same as with already do with the file operations: keep them in .rodata and
prevents people from doing runtime patching.Signed-off-by: Christoph Hellwig
Cc: Steven French
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
23 Jun, 2006
2 commits
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Give the statfs superblock operation a dentry pointer rather than a superblock
pointer.This complements the get_sb() patch. That reduced the significance of
sb->s_root, allowing NFS to place a fake root there. However, NFS does
require a dentry to use as a target for the statfs operation. This permits
the root in the vfsmount to be used instead.linux/mount.h has been added where necessary to make allyesconfig build
successfully.Interest has also been expressed for use with the FUSE and XFS filesystems.
Signed-off-by: David Howells
Acked-by: Al Viro
Cc: Nathan Scott
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.The patch also makes the following changes:
(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.[*] Anonymous until discovered from another tree.
(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells
Acked-by: Al Viro
Cc: Nathan Scott
Cc: Roland Dreier
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
29 Mar, 2006
1 commit
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This is a conversion to make the various file_operations structs in fs/
const. Basically a regexp job, with a few manual fixupsThe goal is both to increase correctness (harder to accidentally write to
shared datastructures) and reducing the false sharing of cachelines with
things that get dirty in .data (while .rodata is nicely read only and thus
cache clean)Signed-off-by: Arjan van de Ven
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
24 Mar, 2006
2 commits
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Rewrap the overly long source code lines resulting from the previous
patch's addition of the slab cache flag SLAB_MEM_SPREAD. This patch
contains only formatting changes, and no function change.Signed-off-by: Paul Jackson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Mark file system inode and similar slab caches subject to SLAB_MEM_SPREAD
memory spreading.If a slab cache is marked SLAB_MEM_SPREAD, then anytime that a task that's
in a cpuset with the 'memory_spread_slab' option enabled goes to allocate
from such a slab cache, the allocations are spread evenly over all the
memory nodes (task->mems_allowed) allowed to that task, instead of favoring
allocation on the node local to the current cpu.The following inode and similar caches are marked SLAB_MEM_SPREAD:
file cache
==== =====
fs/adfs/super.c adfs_inode_cache
fs/affs/super.c affs_inode_cache
fs/befs/linuxvfs.c befs_inode_cache
fs/bfs/inode.c bfs_inode_cache
fs/block_dev.c bdev_cache
fs/cifs/cifsfs.c cifs_inode_cache
fs/coda/inode.c coda_inode_cache
fs/dquot.c dquot
fs/efs/super.c efs_inode_cache
fs/ext2/super.c ext2_inode_cache
fs/ext2/xattr.c (fs/mbcache.c) ext2_xattr
fs/ext3/super.c ext3_inode_cache
fs/ext3/xattr.c (fs/mbcache.c) ext3_xattr
fs/fat/cache.c fat_cache
fs/fat/inode.c fat_inode_cache
fs/freevxfs/vxfs_super.c vxfs_inode
fs/hpfs/super.c hpfs_inode_cache
fs/isofs/inode.c isofs_inode_cache
fs/jffs/inode-v23.c jffs_fm
fs/jffs2/super.c jffs2_i
fs/jfs/super.c jfs_ip
fs/minix/inode.c minix_inode_cache
fs/ncpfs/inode.c ncp_inode_cache
fs/nfs/direct.c nfs_direct_cache
fs/nfs/inode.c nfs_inode_cache
fs/ntfs/super.c ntfs_big_inode_cache_name
fs/ntfs/super.c ntfs_inode_cache
fs/ocfs2/dlm/dlmfs.c dlmfs_inode_cache
fs/ocfs2/super.c ocfs2_inode_cache
fs/proc/inode.c proc_inode_cache
fs/qnx4/inode.c qnx4_inode_cache
fs/reiserfs/super.c reiser_inode_cache
fs/romfs/inode.c romfs_inode_cache
fs/smbfs/inode.c smb_inode_cache
fs/sysv/inode.c sysv_inode_cache
fs/udf/super.c udf_inode_cache
fs/ufs/super.c ufs_inode_cache
net/socket.c sock_inode_cache
net/sunrpc/rpc_pipe.c rpc_inode_cacheThe choice of which slab caches to so mark was quite simple. I marked
those already marked SLAB_RECLAIM_ACCOUNT, except for fs/xfs, dentry_cache,
inode_cache, and buffer_head, which were marked in a previous patch. Even
though SLAB_RECLAIM_ACCOUNT is for a different purpose, it marks the same
potentially large file system i/o related slab caches as we need for memory
spreading.Given that the rule now becomes "wherever you would have used a
SLAB_RECLAIM_ACCOUNT slab cache flag before (usually the inode cache), use
the SLAB_MEM_SPREAD flag too", this should be easy enough to maintain.
Future file system writers will just copy one of the existing file system
slab cache setups and tend to get it right without thinking.Signed-off-by: Paul Jackson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
23 Mar, 2006
1 commit
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Semaphore to mutex conversion.
The conversion was generated via scripts, and the result was validated
automatically via a script as well.Signed-off-by: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
15 Jan, 2006
1 commit
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Remove remaining kmalloc wrapper bits from fs/ncpfs/.
Signed-off-by: Pekka Enberg
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Jan, 2006
1 commit
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fs: Use where capable() is used.
Signed-off-by: Randy Dunlap
Acked-by: Tim Schmielau
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Jan, 2006
1 commit
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To allow various options to work per-mount instead of per-sb we need a
struct vfsmount when updating ctime and mtime. This preparation patch
replaces the inode_update_time routine with a file_update_atime routine so
we can easily get at the vfsmount. (and the file makes more sense in this
context anyway). Also get rid of the unused second argument - we always
want to update the ctime when calling this routine.Signed-off-by: Christoph Hellwig
Cc: Al Viro
Cc: Anton Altaparmakov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 Jan, 2006
1 commit
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Some long time ago, dentry struct was carefully tuned so that on 32 bits
UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple
of memory cache lines.Then RCU was added and dentry struct enlarged by two pointers, with nice
results for SMP, but not so good on UP, because breaking the above tuning
(128 + 8 = 136 bytes)This patch reverts this unwanted side effect, by using an union (d_u),
where d_rcu and d_child are placed so that these two fields can share their
memory needs.At the time d_free() is called (and d_rcu is really used), d_child is known
to be empty and not touched by the dentry freeing.Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so
the previous content of d_child is not needed if said dentry was unhashed
but still accessed by a CPU because of RCU constraints)As dentry cache easily contains millions of entries, a size reduction is
worth the extra complexity of the ugly C union.Signed-off-by: Eric Dumazet
Cc: Dipankar Sarma
Cc: Maneesh Soni
Cc: Miklos Szeredi
Cc: "Paul E. McKenney"
Cc: Ian Kent
Cc: Paul Jackson
Cc: Al Viro
Cc: Christoph Hellwig
Cc: Trond Myklebust
Cc: Neil Brown
Cc: James Morris
Cc: Stephen Smalley
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
