Linus Torvalds 64f371bc31 autofs: make the autofsv5 packet file descriptor use a packetized pipe ... The autofs packet size has had a very unfortunate size problem on x86: because the alignment of 'u64' differs in 32-bit and 64-bit modes, and because the packet data was not 8-byte aligned, the size of the autofsv5 packet structure differed between 32-bit and 64-bit modes despite looking otherwise identical (300 vs 304 bytes respectively). We first fixed that up by making the 64-bit compat mode know about this problem in commit a32744d4ab ("autofs: work around unhappy compat problem on x86-64"), and that made a 32-bit 'systemd' work happily on a 64-bit kernel because everything then worked the same way as on a 32-bit kernel. But it turned out that 'automount' had actually known and worked around this problem in user space, so fixing the kernel to do the proper 32-bit compatibility handling actually *broke* 32-bit automount on a 64-bit kernel, because it knew that the packet sizes were wrong and expected those incorrect sizes. As a result, we ended up reverting that compatibility mode fix, and thus breaking systemd again, in commit fcbf94b9de. With both automount and systemd doing a single read() system call, and verifying that they get *exactly* the size they expect but using different sizes, it seemed that fixing one of them inevitably seemed to break the other. At one point, a patch I seriously considered applying from Michael Tokarev did a "strcmp()" to see if it was automount that was doing the operation. Ugly, ugly. However, a prettier solution exists now thanks to the packetized pipe mode. By marking the communication pipe as being packetized (by simply setting the O_DIRECT flag), we can always just write the bigger packet size, and if user-space does a smaller read, it will just get that partial end result and the extra alignment padding will simply be thrown away. This makes both automount and systemd happy, since they now get the size they asked for, and the kernel side of autofs simply no longer needs to care - it could pad out the packet arbitrarily. Of course, if there is some *other* user of autofs (please, please, please tell me it ain't so - and we haven't heard of any) that tries to read the packets with multiple writes, that other user will now be broken - the whole point of the packetized mode is that one system call gets exactly one packet, and you cannot read a packet in pieces. Tested-by: Michael Tokarev <mjt@tls.msk.ru> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: David Miller <davem@davemloft.net> Cc: Ian Kent <raven@themaw.net> Cc: Thomas Meyer <thomas@m3y3r.de> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2012-04-29 13:30:08 -07:00
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9p
adfs
affs
afs
autofs4	autofs: make the autofsv5 packet file descriptor use a packetized pipe	2012-04-29 13:30:08 -07:00
befs
bfs
btrfs	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs	2012-04-28 09:30:07 -07:00
cachefiles
ceph
cifs	Use correct conversion specifiers in cifs_show_options	2012-04-24 11:36:25 -05:00
coda
configfs
cramfs
debugfs
devpts
dlm
ecryptfs
efs
exofs
exportfs
ext2
ext3
ext4	Ext4 bug fixes for 3.4	2012-04-23 19:52:00 -07:00
fat
freevxfs
fscache
fuse
gfs2	GFS2: Instruct DLM to avoid queue convert slowdown	2012-04-24 13:26:50 +01:00
hfs
hfsplus
hostfs
hpfs
hppfs
hugetlbfs	hugetlbfs: lockdep annotate root inode properly	2012-04-25 21:26:34 -07:00
isofs
jbd
jbd2	jbd2: use GFP_NOFS for blkdev_issue_flush	2012-04-23 21:43:41 -04:00
jffs2
jfs
lockd
logfs
minix
ncpfs
nfs
nfs_common
nfsd
nilfs2
nls
notify
ntfs
ocfs2
omfs
openpromfs
proc	revert "proc: clear_refs: do not clear reserved pages"	2012-04-25 21:26:34 -07:00
pstore
qnx4
qnx6
quota
ramfs
reiserfs
romfs
squashfs
sysfs
sysv
ubifs
udf
ufs
xfs
aio.c
anon_inodes.c
attr.c
bad_inode.c
binfmt_aout.c
binfmt_elf_fdpic.c
binfmt_elf.c
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c
binfmt_script.c
binfmt_som.c
bio-integrity.c
bio.c
block_dev.c
buffer.c	fs/buffer.c: remove BUG() in possible but rare condition	2012-04-25 21:26:33 -07:00
char_dev.c
compat_binfmt_elf.c
compat_ioctl.c
compat.c
dcache.c
dcookies.c
direct-io.c
drop_caches.c
eventfd.c
eventpoll.c	epoll: clear the tfile_check_list on -ELOOP	2012-04-25 21:26:33 -07:00
exec.c
fcntl.c
fhandle.c
fifo.c
file_table.c
file.c
filesystems.c
fs_struct.c
fs-writeback.c
generic_acl.c
inode.c
internal.h
ioctl.c
ioprio.c
Kconfig
Kconfig.binfmt
libfs.c
locks.c
Makefile
mbcache.c
mount.h
mpage.c
namei.c
namespace.c
no-block.c
open.c
pipe.c	pipes: add a "packetized pipe" mode for writing	2012-04-29 13:12:42 -07:00
pnode.c
pnode.h
posix_acl.c
proc_namespace.c
read_write.c
read_write.h
readdir.c
select.c
seq_file.c
signalfd.c
splice.c
stack.c
stat.c
statfs.c
super.c
sync.c
timerfd.c
utimes.c
xattr_acl.c
xattr.c