- 17 4月, 2013 1 次提交
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由 Matt Fleming 提交于
Now that efivarfs uses the efivar API, move it out of efivars.c and into fs/efivarfs where it belongs. This move will eventually allow us to enable the efivarfs code without having to also enable CONFIG_EFI_VARS built, and vice versa. Furthermore, things like, mount -t efivarfs none /sys/firmware/efi/efivars will now work if efivarfs is built as a module without requiring the use of MODULE_ALIAS(), which would have been necessary when the efivarfs code was part of efivars.c. Cc: Matthew Garrett <matthew.garrett@nebula.com> Cc: Jeremy Kerr <jk@ozlabs.org> Reviewed-by: NTom Gundersen <teg@jklm.no> Tested-by: NTom Gundersen <teg@jklm.no> Signed-off-by: NMatt Fleming <matt.fleming@intel.com>
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- 17 1月, 2013 1 次提交
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由 Robert P. J. Day 提交于
Given that CUSE depends on FUSE, it only makes sense to move its Kconfig entry into the FUSE Kconfig file. Also, add a few grammatical and semantic touchups. Signed-off-by: NRobert P. J. Day <rpjday@crashcourse.ca> Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
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- 11 12月, 2012 2 次提交
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由 Jaegeuk Kim 提交于
This adds Makefile and Kconfig for f2fs, and updates Makefile and Kconfig files in the fs directory. Signed-off-by: NJaegeuk Kim <jaegeuk.kim@samsung.com>
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由 Tao Ma 提交于
Ted has sent out a RFC about removing this feature. Eric and Jan confirmed that both RedHat and SUSE enable this feature in all their product. David also said that "As far as I know, it's enabled in all Android kernels that use ext4." So it seems OK for us. And what's more, as inline data depends its implementation on xattr, and to be frank, I don't run any test again inline data enabled while xattr disabled. So I think we should add inline data and remove this config option in the same release. [ The savings if you disable CONFIG_EXT4_FS_XATTR is only 27k, which isn't much in the grand scheme of things. Since no one seems to be testing this configuration except for some automated compile farms, on balance we are better removing this config option, and so that it is effectively always enabled. -- tytso ] Cc: David Brown <davidb@codeaurora.org> Cc: Eric Sandeen <sandeen@redhat.com> Reviewed-by: NJan Kara <jack@suse.cz> Signed-off-by: NTao Ma <boyu.mt@taobao.com> Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
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- 21 3月, 2012 1 次提交
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由 Kai Bankett 提交于
Adds support for qnx6fs readonly support to the linux kernel. * Mount option The option mmi_fs can be used to mount Harman Becker/Audi MMI 3G HDD qnx6fs filesystems. * Documentation A high level filesystem stucture description can be found in the Documentation/filesystems directory. (qnx6.txt) * Additional features - Active (stable) superblock selection - Superblock checksum check (enforced) - Supports mount of qnx6 filesystems with to host different endianess - Automatic endianess detection - Longfilename support (with non-enfocing crc check) - All blocksizes (512, 1024, 2048 and 4096 supported) Signed-off-by: NKai Bankett <chaosman@ontika.net> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 09 3月, 2012 1 次提交
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由 Linus Torvalds 提交于
Ok, this is hacky, and only works on little-endian machines with goo unaligned handling. And even then only with CONFIG_DEBUG_PAGEALLOC disabled, since it can access up to 7 bytes after the pathname. But it runs like a bat out of hell. Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 06 1月, 2012 1 次提交
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由 Boaz Harrosh 提交于
As Reported by Randy Dunlap When MISC_FILESYSTEMS is not enabled and NFS4.1 is: fs/built-in.o: In function `objio_alloc_io_state': objio_osd.c:(.text+0xcb525): undefined reference to `ore_get_rw_state' fs/built-in.o: In function `_write_done': objio_osd.c:(.text+0xcb58d): undefined reference to `ore_check_io' fs/built-in.o: In function `_read_done': ... When MISC_FILESYSTEMS, which is more of a GUI thing then anything else, is not selected. exofs/Kconfig is never examined during Kconfig, and it can not do it's magic stuff to automatically select everything needed. We must split exofs/Kconfig in two. The ore one is always included. And the exofs one is left in it's old place in the menu. [Needed for the 3.2.0 Kernel] CC: Stable Tree <stable@kernel.org> Reported-by: NRandy Dunlap <rdunlap@xenotime.net> Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>
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- 04 1月, 2012 1 次提交
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 01 11月, 2011 1 次提交
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由 Robert P. J. Day 提交于
Add the leading word "tmpfs" to the Kconfig string to make it blindingly obvious that this selection refers to tmpfs. Signed-off-by: NRobert P. J. Day <rpjday@crashcourse.ca> Acked-by: NHugh Dickins <hughd@google.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 04 8月, 2011 1 次提交
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由 Robert P. J. Day 提交于
Expand the fs/Kconfig "help" info to clarify why it's a bad idea to deselect the TMPFS_POSIX_ACL config variable. Signed-off-by: NRobert P. J. Day <rpjday@crashcourse.ca> Acked-by: NRandy Dunlap <rdunlap@xenotime.net> Acked-by: NHugh Dickins <hughd@google.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 26 5月, 2011 2 次提交
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由 Jonas Gorski 提交于
Commit 990d6c2d ("vfs: Add name to file handle conversion support") changed EXPORTFS to be a bool. This was needed for earlier revisions of the original patch, but the actual commit put the code needing it into its own file that only gets compiled when FHANDLE is selected which in turn selects EXPORTFS. So EXPORTFS can be safely compiled as a module when not selecting FHANDLE. Signed-off-by: NJonas Gorski <jonas.gorski@gmail.com> Acked-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Eric Paris 提交于
Choosing TMPFS_XATTR default N was switching off TMPFS_POSIX_ACL, even if it had been Y in oldconfig; and Linus reports that PulseAudio goes subtly wrong unless it can use ACLs on /dev/shm. Make TMPFS_POSIX_ACL select TMPFS_XATTR (and depend upon TMPFS), and move the TMPFS_POSIX_ACL entry before the TMPFS_XATTR entry, to avoid asking unnecessary questions then ignoring their answers. Signed-off-by: NHugh Dickins <hughd@google.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 25 5月, 2011 1 次提交
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由 Eric Paris 提交于
Implement generic xattrs for tmpfs filesystems. The Feodra project, while trying to replace suid apps with file capabilities, realized that tmpfs, which is used on the build systems, does not support file capabilities and thus cannot be used to build packages which use file capabilities. Xattrs are also needed for overlayfs. The xattr interface is a bit odd. If a filesystem does not implement any {get,set,list}xattr functions the VFS will call into some random LSM hooks and the running LSM can then implement some method for handling xattrs. SELinux for example provides a method to support security.selinux but no other security.* xattrs. As it stands today when one enables CONFIG_TMPFS_POSIX_ACL tmpfs will have xattr handler routines specifically to handle acls. Because of this tmpfs would loose the VFS/LSM helpers to support the running LSM. To make up for that tmpfs had stub functions that did nothing but call into the LSM hooks which implement the helpers. This new patch does not use the LSM fallback functions and instead just implements a native get/set/list xattr feature for the full security.* and trusted.* namespace like a normal filesystem. This means that tmpfs can now support both security.selinux and security.capability, which was not previously possible. The basic implementation is that I attach a: struct shmem_xattr { struct list_head list; /* anchored by shmem_inode_info->xattr_list */ char *name; size_t size; char value[0]; }; Into the struct shmem_inode_info for each xattr that is set. This implementation could easily support the user.* namespace as well, except some care needs to be taken to prevent large amounts of unswappable memory being allocated for unprivileged users. [mszeredi@suse.cz: new config option, suport trusted.*, support symlinks] Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> Acked-by: NSerge Hallyn <serge.hallyn@ubuntu.com> Tested-by: NSerge Hallyn <serge.hallyn@ubuntu.com> Cc: Kyle McMartin <kyle@mcmartin.ca> Acked-by: NHugh Dickins <hughd@google.com> Tested-by: NJordi Pujol <jordipujolp@gmail.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 15 3月, 2011 1 次提交
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由 Aneesh Kumar K.V 提交于
The syscall also return mount id which can be used to lookup file system specific information such as uuid in /proc/<pid>/mountinfo Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 21 1月, 2011 1 次提交
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由 David Rientjes 提交于
The meaning of CONFIG_EMBEDDED has long since been obsoleted; the option is used to configure any non-standard kernel with a much larger scope than only small devices. This patch renames the option to CONFIG_EXPERT in init/Kconfig and fixes references to the option throughout the kernel. A new CONFIG_EMBEDDED option is added that automatically selects CONFIG_EXPERT when enabled and can be used in the future to isolate options that should only be considered for embedded systems (RISC architectures, SLOB, etc). Calling the option "EXPERT" more accurately represents its intention: only expert users who understand the impact of the configuration changes they are making should enable it. Reviewed-by: NIngo Molnar <mingo@elte.hu> Acked-by: NDavid Woodhouse <david.woodhouse@intel.com> Signed-off-by: NDavid Rientjes <rientjes@google.com> Cc: Greg KH <gregkh@suse.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jens Axboe <axboe@kernel.dk> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Robin Holt <holt@sgi.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 17 1月, 2011 1 次提交
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由 Randy Dunlap 提交于
- Fix a kconfig unmet dependency warning. - Remove the comment that identifies which filesystems use POSIX ACL utility routines. - Move the FS_POSIX_ACL symbol outside of the BLOCK symbol if/endif block because its functions do not depend on BLOCK and some of the filesystems that use it do not depend on BLOCK. warning: (GENERIC_ACL && JFFS2_FS_POSIX_ACL && NFSD_V4 && NFS_ACL_SUPPORT && 9P_FS_POSIX_ACL) selects FS_POSIX_ACL which has unmet direct dependencies (BLOCK) Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 29 12月, 2010 1 次提交
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由 Tony Luck 提交于
Some platforms have a small amount of non-volatile storage that can be used to store information useful to diagnose the cause of a system crash. This is the generic part of a file system interface that presents information from the crash as a series of files in /dev/pstore. Once the information has been seen, the underlying storage is freed by deleting the files. Signed-off-by: NTony Luck <tony.luck@intel.com>
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- 28 10月, 2010 1 次提交
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由 Arnd Bergmann 提交于
Nothing depends on lock_flocks using the BKL any more, so we can do the switch over to a private spinlock. Signed-off-by: NArnd Bergmann <arnd@arndb.de>
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- 27 10月, 2010 1 次提交
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由 Randy Dunlap 提交于
Move the EXPORTFS kconfig symbol out of the NETWORK_FILESYSTEMS block since it provides a library function that can be (and is) used by other (non-network) filesystems. This also eliminates a kconfig dependency warning: warning: (XFS_FS && BLOCK || NFSD && NETWORK_FILESYSTEMS && INET && FILE_LOCKING && BKL) selects EXPORTFS which has unmet direct dependencies (NETWORK_FILESYSTEMS) Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Alex Elder <aelder@sgi.com> Reviewed-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 26 10月, 2010 1 次提交
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由 Randy Dunlap 提交于
Move the EXPORTFS kconfig symbol out of the NETWORK_FILESYSTEMS block since it provides a library function that can be (and is) used by other (non-network) filesystems. This also eliminates a kconfig dependency warning: warning: (XFS_FS && BLOCK || NFSD && NETWORK_FILESYSTEMS && INET && FILE_LOCKING && BKL) selects EXPORTFS which has unmet direct dependencies (NETWORK_FILESYSTEMS) Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Alex Elder <aelder@sgi.com> Cc: xfs-masters@oss.sgi.com Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 21 10月, 2010 1 次提交
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由 Arnd Bergmann 提交于
With all the patches we have queued in the BKL removal tree, only a few dozen modules are left that actually rely on the BKL, and even there are lots of low-hanging fruit. We need to decide what to do about them, this patch illustrates one of the options: Every user of the BKL is marked as 'depends on BKL' in Kconfig, and the CONFIG_BKL becomes a user-visible option. If it gets disabled, no BKL using module can be built any more and the BKL code itself is compiled out. The one exception is file locking, which is practically always enabled and does a 'select BKL' instead. This effectively forces CONFIG_BKL to be enabled until we have solved the fs/lockd mess and can apply the patch that removes the BKL from fs/locks.c. Signed-off-by: NArnd Bergmann <arnd@arndb.de>
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- 06 10月, 2010 2 次提交
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由 Arnd Bergmann 提交于
smbfs has been scheduled for removal in 2.6.27, so maybe we can now move it to drivers/staging on the way out. smbfs still uses the big kernel lock and nobody is going to fix that, so we should be getting rid of it soon. This removes the 32 bit compat mount and ioctl handling code, which is implemented in common fs code, and moves all smbfs related files into drivers/staging/smbfs. Signed-off-by: NArnd Bergmann <arnd@arndb.de> Acked-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
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由 Arnd Bergmann 提交于
Nobody appears to be interested in fixing autofs3 bugs any more and it uses the BKL, which is going away. Move this to staging for retirement. Unless someone complains until 2.6.38, we can remove it for good. The include/linux/auto_fs.h header file is still used by autofs4, so it remains in place. Signed-off-by: NArnd Bergmann <arnd@arndb.de> Cc: Ian Kent <raven@themaw.net> Cc: autofs@linux.kernel.org Cc: "H. Peter Anvin" <hpa@zytor.com> Acked-by: NH. Peter Anvin <hpa@zytor.com> Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
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- 20 7月, 2010 1 次提交
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由 Stephen Boyd 提交于
Signed-off-by: NStephen Boyd <bebarino@gmail.com> Signed-off-by: NJiri Kosina <jkosina@suse.cz>
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- 18 12月, 2009 1 次提交
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由 Linus Torvalds 提交于
This reverts commit e4c570c4, as requested by Alexey: "I think I gave a good enough arguments to not merge it. To iterate: * patch makes impossible to start using ext3 on EXT3_FS=n kernels without reboot. * this is done only for one pointer on task_struct" None of config options which define task_struct are tristate directly or effectively." Requested-by: NAlexey Dobriyan <adobriyan@gmail.com> Acked-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 16 12月, 2009 1 次提交
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由 Hiroshi Shimamoto 提交于
journal_info in task_struct is used in journaling file system only. So introduce CONFIG_FS_JOURNAL_INFO and make it conditional. Signed-off-by: NHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 21 11月, 2009 1 次提交
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由 Joern Engel 提交于
This is a new flash file system. See Documentation/filesystems/logfs.txt Signed-off-by: NJoern Engel <joern@logfs.org>
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- 30 10月, 2009 1 次提交
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由 Benjamin Herrenschmidt 提交于
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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- 27 10月, 2009 2 次提交
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由 Kumar Gala 提交于
Signed-off-by: NKumar Gala <galak@kernel.crashing.org> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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由 Paul Mundt 提交于
The hugetlb dependencies presently depend on SUPERH && MMU while the hugetlb page size definitions depend on CPU_SH4 or CPU_SH5. This unfortunately allows SH-3 + MMU configurations to enable hugetlbfs without a corresponding HPAGE_SHIFT definition, resulting in the build blowing up. As SH-3 doesn't support variable page sizes, we tighten up the dependenies a bit to prevent hugetlbfs from being enabled. These days we also have a shiny new SYS_SUPPORTS_HUGETLBFS, so switch to using that rather than adding to the list of corner cases in fs/Kconfig. Reported-by: NKristoffer Ericson <kristoffer.ericson@gmail.com> Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
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- 07 10月, 2009 1 次提交
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由 Sage Weil 提交于
Kconfig options and Makefile. Signed-off-by: NSage Weil <sage@newdream.net>
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- 22 9月, 2009 1 次提交
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由 Hugh Dickins 提交于
CONFIG_SHMEM off gives you (ramfs masquerading as) tmpfs, even when CONFIG_TMPFS is off: that's a little anomalous, and I'd intended to make more sense of it by removing CONFIG_TMPFS altogether, always enabling its code when CONFIG_SHMEM; but so many defconfigs have CONFIG_SHMEM on CONFIG_TMPFS off that we'd better leave that as is. But there is no point in asking for CONFIG_TMPFS if CONFIG_SHMEM is off: make TMPFS depend on SHMEM, which also prevents TMPFS_POSIX_ACL shmem_acl.o being pointlessly built into the kernel when SHMEM is off. And a selfish change, to prevent the world from being rebuilt when I switch between CONFIG_SHMEM on and off: the only CONFIG_SHMEM in the header files is mm.h shmem_lock() - give that a shmem.c stub instead. Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: NMatt Mackall <mpm@selenic.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 14 9月, 2009 1 次提交
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由 Ryusuke Konishi 提交于
Some people asked me questions like the following: On Wed, 15 Jul 2009 13:11:21 +0200, Leon Woestenberg wrote: > just wondering, any reasons why NILFS2 is one of the miscellaneous > filesystems and, for example, btrfs, is not in Kconfig? Actually, nilfs is NOT a filesystem came from other operating systems, but a filesystem created purely for Linux. Nor is it a flash filesystem but that for generic block devices. So, this moves nilfs outside the misc category as I responded in LKML "Re: Why does NILFS2 hide under Miscellaneous filesystems?" (Message-Id: <20090716.002526.93465395.ryusuke@osrg.net>). Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
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- 14 7月, 2009 1 次提交
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由 Ryusuke Konishi 提交于
fs/Kconfig file was split into individual fs/*/Kconfig files before nilfs was merged. I've found the current config entry of nilfs is tainting the work. Sorry, I didn't notice. This fixes the violation. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: Alexey Dobriyan <adobriyan@gmail.com>
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- 17 6月, 2009 2 次提交
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由 David Daney 提交于
As part of adding hugetlbfs support for MIPS, I am adding a new kconfig variable 'SYS_SUPPORTS_HUGETLBFS'. Since some mips cpu varients don't yet support it, we can enable selection of HUGETLBFS on a system by system basis from the arch/mips/Kconfig. Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com> CC: William Irwin <wli@holomorphy.com> Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
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由 Tomas Szepe 提交于
CONFIG_FILE_LOCKING should not depend on CONFIG_BLOCK. This makes it possible to run complete systems out of a CONFIG_BLOCK=n initramfs on current kernels again (this last worked on 2.6.27.*). Cc: <stable@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 09 6月, 2009 1 次提交
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由 Tejun Heo 提交于
CUSE enables implementing character devices in userspace. With recent additions of ioctl and poll support, FUSE already has most of what's necessary to implement character devices. All CUSE has to do is bonding all those components - FUSE, chardev and the driver model - nicely. When client opens /dev/cuse, kernel starts conversation with CUSE_INIT. The client tells CUSE which device it wants to create. As the previous patch made fuse_file usable without associated fuse_inode, CUSE doesn't create super block or inodes. It attaches fuse_file to cdev file->private_data during open and set ff->fi to NULL. The rest of the operation is almost identical to FUSE direct IO case. Each CUSE device has a corresponding directory /sys/class/cuse/DEVNAME (which is symlink to /sys/devices/virtual/class/DEVNAME if SYSFS_DEPRECATED is turned off) which hosts "waiting" and "abort" among other things. Those two files have the same meaning as the FUSE control files. The only notable lacking feature compared to in-kernel implementation is mmap support. Signed-off-by: NTejun Heo <tj@kernel.org> Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
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- 14 5月, 2009 1 次提交
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由 Randy Dunlap 提交于
lockd/svclock.c is missing a header file <linux/fs.h>. <linux/fs.h> is missing a definition of locks_release_private() for the config case of FILE_LOCKING=n, causing a build error: fs/lockd/svclock.c:330: error: implicit declaration of function 'locks_release_private' lockd without FILE_LOCKING doesn't make sense, so make LOCKD and LOCKD_V4 depend on FILE_LOCKING, and make NFS depend on FILE_LOCKING. Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
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- 07 4月, 2009 1 次提交
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由 Ryusuke Konishi 提交于
This adds a Makefile for the nilfs2 file system, and updates the makefile and Kconfig file in the file system directory. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 03 4月, 2009 1 次提交
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由 David Howells 提交于
Add an FS-Cache cache-backend that permits a mounted filesystem to be used as a backing store for the cache. CacheFiles uses a userspace daemon to do some of the cache management - such as reaping stale nodes and culling. This is called cachefilesd and lives in /sbin. The source for the daemon can be downloaded from: http://people.redhat.com/~dhowells/cachefs/cachefilesd.c And an example configuration from: http://people.redhat.com/~dhowells/cachefs/cachefilesd.conf The filesystem and data integrity of the cache are only as good as those of the filesystem providing the backing services. Note that CacheFiles does not attempt to journal anything since the journalling interfaces of the various filesystems are very specific in nature. CacheFiles creates a misc character device - "/dev/cachefiles" - that is used to communication with the daemon. Only one thing may have this open at once, and whilst it is open, a cache is at least partially in existence. The daemon opens this and sends commands down it to control the cache. CacheFiles is currently limited to a single cache. CacheFiles attempts to maintain at least a certain percentage of free space on the filesystem, shrinking the cache by culling the objects it contains to make space if necessary - see the "Cache Culling" section. This means it can be placed on the same medium as a live set of data, and will expand to make use of spare space and automatically contract when the set of data requires more space. ============ REQUIREMENTS ============ The use of CacheFiles and its daemon requires the following features to be available in the system and in the cache filesystem: - dnotify. - extended attributes (xattrs). - openat() and friends. - bmap() support on files in the filesystem (FIBMAP ioctl). - The use of bmap() to detect a partial page at the end of the file. It is strongly recommended that the "dir_index" option is enabled on Ext3 filesystems being used as a cache. ============= CONFIGURATION ============= The cache is configured by a script in /etc/cachefilesd.conf. These commands set up cache ready for use. The following script commands are available: (*) brun <N>% (*) bcull <N>% (*) bstop <N>% (*) frun <N>% (*) fcull <N>% (*) fstop <N>% Configure the culling limits. Optional. See the section on culling The defaults are 7% (run), 5% (cull) and 1% (stop) respectively. The commands beginning with a 'b' are file space (block) limits, those beginning with an 'f' are file count limits. (*) dir <path> Specify the directory containing the root of the cache. Mandatory. (*) tag <name> Specify a tag to FS-Cache to use in distinguishing multiple caches. Optional. The default is "CacheFiles". (*) debug <mask> Specify a numeric bitmask to control debugging in the kernel module. Optional. The default is zero (all off). The following values can be OR'd into the mask to collect various information: 1 Turn on trace of function entry (_enter() macros) 2 Turn on trace of function exit (_leave() macros) 4 Turn on trace of internal debug points (_debug()) This mask can also be set through sysfs, eg: echo 5 >/sys/modules/cachefiles/parameters/debug ================== STARTING THE CACHE ================== The cache is started by running the daemon. The daemon opens the cache device, configures the cache and tells it to begin caching. At that point the cache binds to fscache and the cache becomes live. The daemon is run as follows: /sbin/cachefilesd [-d]* [-s] [-n] [-f <configfile>] The flags are: (*) -d Increase the debugging level. This can be specified multiple times and is cumulative with itself. (*) -s Send messages to stderr instead of syslog. (*) -n Don't daemonise and go into background. (*) -f <configfile> Use an alternative configuration file rather than the default one. =============== THINGS TO AVOID =============== Do not mount other things within the cache as this will cause problems. The kernel module contains its own very cut-down path walking facility that ignores mountpoints, but the daemon can't avoid them. Do not create, rename or unlink files and directories in the cache whilst the cache is active, as this may cause the state to become uncertain. Renaming files in the cache might make objects appear to be other objects (the filename is part of the lookup key). Do not change or remove the extended attributes attached to cache files by the cache as this will cause the cache state management to get confused. Do not create files or directories in the cache, lest the cache get confused or serve incorrect data. Do not chmod files in the cache. The module creates things with minimal permissions to prevent random users being able to access them directly. ============= CACHE CULLING ============= The cache may need culling occasionally to make space. This involves discarding objects from the cache that have been used less recently than anything else. Culling is based on the access time of data objects. Empty directories are culled if not in use. Cache culling is done on the basis of the percentage of blocks and the percentage of files available in the underlying filesystem. There are six "limits": (*) brun (*) frun If the amount of free space and the number of available files in the cache rises above both these limits, then culling is turned off. (*) bcull (*) fcull If the amount of available space or the number of available files in the cache falls below either of these limits, then culling is started. (*) bstop (*) fstop If the amount of available space or the number of available files in the cache falls below either of these limits, then no further allocation of disk space or files is permitted until culling has raised things above these limits again. These must be configured thusly: 0 <= bstop < bcull < brun < 100 0 <= fstop < fcull < frun < 100 Note that these are percentages of available space and available files, and do _not_ appear as 100 minus the percentage displayed by the "df" program. The userspace daemon scans the cache to build up a table of cullable objects. These are then culled in least recently used order. A new scan of the cache is started as soon as space is made in the table. Objects will be skipped if their atimes have changed or if the kernel module says it is still using them. =============== CACHE STRUCTURE =============== The CacheFiles module will create two directories in the directory it was given: (*) cache/ (*) graveyard/ The active cache objects all reside in the first directory. The CacheFiles kernel module moves any retired or culled objects that it can't simply unlink to the graveyard from which the daemon will actually delete them. The daemon uses dnotify to monitor the graveyard directory, and will delete anything that appears therein. The module represents index objects as directories with the filename "I..." or "J...". Note that the "cache/" directory is itself a special index. Data objects are represented as files if they have no children, or directories if they do. Their filenames all begin "D..." or "E...". If represented as a directory, data objects will have a file in the directory called "data" that actually holds the data. Special objects are similar to data objects, except their filenames begin "S..." or "T...". If an object has children, then it will be represented as a directory. Immediately in the representative directory are a collection of directories named for hash values of the child object keys with an '@' prepended. Into this directory, if possible, will be placed the representations of the child objects: INDEX INDEX INDEX DATA FILES ========= ========== ================================= ================ cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400 cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...DB1ry cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...N22ry cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...FP1ry If the key is so long that it exceeds NAME_MAX with the decorations added on to it, then it will be cut into pieces, the first few of which will be used to make a nest of directories, and the last one of which will be the objects inside the last directory. The names of the intermediate directories will have '+' prepended: J1223/@23/+xy...z/+kl...m/Epqr Note that keys are raw data, and not only may they exceed NAME_MAX in size, they may also contain things like '/' and NUL characters, and so they may not be suitable for turning directly into a filename. To handle this, CacheFiles will use a suitably printable filename directly and "base-64" encode ones that aren't directly suitable. The two versions of object filenames indicate the encoding: OBJECT TYPE PRINTABLE ENCODED =============== =============== =============== Index "I..." "J..." Data "D..." "E..." Special "S..." "T..." Intermediate directories are always "@" or "+" as appropriate. Each object in the cache has an extended attribute label that holds the object type ID (required to distinguish special objects) and the auxiliary data from the netfs. The latter is used to detect stale objects in the cache and update or retire them. Note that CacheFiles will erase from the cache any file it doesn't recognise or any file of an incorrect type (such as a FIFO file or a device file). ========================== SECURITY MODEL AND SELINUX ========================== CacheFiles is implemented to deal properly with the LSM security features of the Linux kernel and the SELinux facility. One of the problems that CacheFiles faces is that it is generally acting on behalf of a process, and running in that process's context, and that includes a security context that is not appropriate for accessing the cache - either because the files in the cache are inaccessible to that process, or because if the process creates a file in the cache, that file may be inaccessible to other processes. The way CacheFiles works is to temporarily change the security context (fsuid, fsgid and actor security label) that the process acts as - without changing the security context of the process when it the target of an operation performed by some other process (so signalling and suchlike still work correctly). When the CacheFiles module is asked to bind to its cache, it: (1) Finds the security label attached to the root cache directory and uses that as the security label with which it will create files. By default, this is: cachefiles_var_t (2) Finds the security label of the process which issued the bind request (presumed to be the cachefilesd daemon), which by default will be: cachefilesd_t and asks LSM to supply a security ID as which it should act given the daemon's label. By default, this will be: cachefiles_kernel_t SELinux transitions the daemon's security ID to the module's security ID based on a rule of this form in the policy. type_transition <daemon's-ID> kernel_t : process <module's-ID>; For instance: type_transition cachefilesd_t kernel_t : process cachefiles_kernel_t; The module's security ID gives it permission to create, move and remove files and directories in the cache, to find and access directories and files in the cache, to set and access extended attributes on cache objects, and to read and write files in the cache. The daemon's security ID gives it only a very restricted set of permissions: it may scan directories, stat files and erase files and directories. It may not read or write files in the cache, and so it is precluded from accessing the data cached therein; nor is it permitted to create new files in the cache. There are policy source files available in: http://people.redhat.com/~dhowells/fscache/cachefilesd-0.8.tar.bz2 and later versions. In that tarball, see the files: cachefilesd.te cachefilesd.fc cachefilesd.if They are built and installed directly by the RPM. If a non-RPM based system is being used, then copy the above files to their own directory and run: make -f /usr/share/selinux/devel/Makefile semodule -i cachefilesd.pp You will need checkpolicy and selinux-policy-devel installed prior to the build. By default, the cache is located in /var/fscache, but if it is desirable that it should be elsewhere, than either the above policy files must be altered, or an auxiliary policy must be installed to label the alternate location of the cache. For instructions on how to add an auxiliary policy to enable the cache to be located elsewhere when SELinux is in enforcing mode, please see: /usr/share/doc/cachefilesd-*/move-cache.txt When the cachefilesd rpm is installed; alternatively, the document can be found in the sources. ================== A NOTE ON SECURITY ================== CacheFiles makes use of the split security in the task_struct. It allocates its own task_security structure, and redirects current->act_as to point to it when it acts on behalf of another process, in that process's context. The reason it does this is that it calls vfs_mkdir() and suchlike rather than bypassing security and calling inode ops directly. Therefore the VFS and LSM may deny the CacheFiles access to the cache data because under some circumstances the caching code is running in the security context of whatever process issued the original syscall on the netfs. Furthermore, should CacheFiles create a file or directory, the security parameters with that object is created (UID, GID, security label) would be derived from that process that issued the system call, thus potentially preventing other processes from accessing the cache - including CacheFiles's cache management daemon (cachefilesd). What is required is to temporarily override the security of the process that issued the system call. We can't, however, just do an in-place change of the security data as that affects the process as an object, not just as a subject. This means it may lose signals or ptrace events for example, and affects what the process looks like in /proc. So CacheFiles makes use of a logical split in the security between the objective security (task->sec) and the subjective security (task->act_as). The objective security holds the intrinsic security properties of a process and is never overridden. This is what appears in /proc, and is what is used when a process is the target of an operation by some other process (SIGKILL for example). The subjective security holds the active security properties of a process, and may be overridden. This is not seen externally, and is used whan a process acts upon another object, for example SIGKILLing another process or opening a file. LSM hooks exist that allow SELinux (or Smack or whatever) to reject a request for CacheFiles to run in a context of a specific security label, or to create files and directories with another security label. This documentation is added by the patch to: Documentation/filesystems/caching/cachefiles.txt Signed-Off-By: NDavid Howells <dhowells@redhat.com> Acked-by: NSteve Dickson <steved@redhat.com> Acked-by: NTrond Myklebust <Trond.Myklebust@netapp.com> Acked-by: NAl Viro <viro@zeniv.linux.org.uk> Tested-by: NDaire Byrne <Daire.Byrne@framestore.com>
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