e9be9d5e76
Overlayfs allows one, usually read-write, directory tree to be overlaid onto another, read-only directory tree. All modifications go to the upper, writable layer. This type of mechanism is most often used for live CDs but there's a wide variety of other uses. The implementation differs from other "union filesystem" implementations in that after a file is opened all operations go directly to the underlying, lower or upper, filesystems. This simplifies the implementation and allows native performance in these cases. The dentry tree is duplicated from the underlying filesystems, this enables fast cached lookups without adding special support into the VFS. This uses slightly more memory than union mounts, but dentries are relatively small. Currently inodes are duplicated as well, but it is a possible optimization to share inodes for non-directories. Opening non directories results in the open forwarded to the underlying filesystem. This makes the behavior very similar to union mounts (with the same limitations vs. fchmod/fchown on O_RDONLY file descriptors). Usage: mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper/upper,workdir=/upper/work /overlay The following cotributions have been folded into this patch: Neil Brown <neilb@suse.de>: - minimal remount support - use correct seek function for directories - initialise is_real before use - rename ovl_fill_cache to ovl_dir_read Felix Fietkau <nbd@openwrt.org>: - fix a deadlock in ovl_dir_read_merged - fix a deadlock in ovl_remove_whiteouts Erez Zadok <ezk@fsl.cs.sunysb.edu> - fix cleanup after WARN_ON Sedat Dilek <sedat.dilek@googlemail.com> - fix up permission to confirm to new API Robin Dong <hao.bigrat@gmail.com> - fix possible leak in ovl_new_inode - create new inode in ovl_link Andy Whitcroft <apw@canonical.com> - switch to __inode_permission() - copy up i_uid/i_gid from the underlying inode AV: - ovl_copy_up_locked() - dput(ERR_PTR(...)) on two failure exits - ovl_clear_empty() - one failure exit forgetting to do unlock_rename(), lack of check for udir being the parent of upper, dropping and regaining the lock on udir (which would require _another_ check for parent being right). - bogus d_drop() in copyup and rename [fix from your mail] - copyup/remove and copyup/rename races [fix from your mail] - ovl_dir_fsync() leaving ERR_PTR() in ->realfile - ovl_entry_free() is pointless - it's just a kfree_rcu() - fold ovl_do_lookup() into ovl_lookup() - manually assigning ->d_op is wrong. Just use ->s_d_op. [patches picked from Miklos]: * copyup/remove and copyup/rename races * bogus d_drop() in copyup and rename Also thanks to the following people for testing and reporting bugs: Jordi Pujol <jordipujolp@gmail.com> Andy Whitcroft <apw@canonical.com> Michal Suchanek <hramrach@centrum.cz> Felix Fietkau <nbd@openwrt.org> Erez Zadok <ezk@fsl.cs.sunysb.edu> Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
274 lines
6.0 KiB
Plaintext
274 lines
6.0 KiB
Plaintext
#
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# File system configuration
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#
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menu "File systems"
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# Use unaligned word dcache accesses
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config DCACHE_WORD_ACCESS
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bool
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if BLOCK
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source "fs/ext2/Kconfig"
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source "fs/ext3/Kconfig"
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source "fs/ext4/Kconfig"
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config FS_XIP
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# execute in place
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bool
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depends on EXT2_FS_XIP
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default y
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source "fs/jbd/Kconfig"
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source "fs/jbd2/Kconfig"
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config FS_MBCACHE
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# Meta block cache for Extended Attributes (ext2/ext3/ext4)
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tristate
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default y if EXT2_FS=y && EXT2_FS_XATTR
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default y if EXT3_FS=y && EXT3_FS_XATTR
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default y if EXT4_FS=y
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default m if EXT2_FS_XATTR || EXT3_FS_XATTR || EXT4_FS
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source "fs/reiserfs/Kconfig"
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source "fs/jfs/Kconfig"
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source "fs/xfs/Kconfig"
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source "fs/gfs2/Kconfig"
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source "fs/ocfs2/Kconfig"
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source "fs/btrfs/Kconfig"
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source "fs/nilfs2/Kconfig"
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endif # BLOCK
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# Posix ACL utility routines
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#
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# Note: Posix ACLs can be implemented without these helpers. Never use
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# this symbol for ifdefs in core code.
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#
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config FS_POSIX_ACL
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def_bool n
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config EXPORTFS
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tristate
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config FILE_LOCKING
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bool "Enable POSIX file locking API" if EXPERT
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default y
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help
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This option enables standard file locking support, required
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for filesystems like NFS and for the flock() system
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call. Disabling this option saves about 11k.
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source "fs/notify/Kconfig"
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source "fs/quota/Kconfig"
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source "fs/autofs4/Kconfig"
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source "fs/fuse/Kconfig"
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source "fs/overlayfs/Kconfig"
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menu "Caches"
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source "fs/fscache/Kconfig"
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source "fs/cachefiles/Kconfig"
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endmenu
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if BLOCK
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menu "CD-ROM/DVD Filesystems"
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source "fs/isofs/Kconfig"
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source "fs/udf/Kconfig"
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endmenu
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endif # BLOCK
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if BLOCK
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menu "DOS/FAT/NT Filesystems"
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source "fs/fat/Kconfig"
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source "fs/ntfs/Kconfig"
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endmenu
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endif # BLOCK
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menu "Pseudo filesystems"
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source "fs/proc/Kconfig"
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source "fs/kernfs/Kconfig"
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source "fs/sysfs/Kconfig"
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config TMPFS
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bool "Tmpfs virtual memory file system support (former shm fs)"
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depends on SHMEM
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help
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Tmpfs is a file system which keeps all files in virtual memory.
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Everything in tmpfs is temporary in the sense that no files will be
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created on your hard drive. The files live in memory and swap
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space. If you unmount a tmpfs instance, everything stored therein is
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lost.
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See <file:Documentation/filesystems/tmpfs.txt> for details.
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config TMPFS_POSIX_ACL
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bool "Tmpfs POSIX Access Control Lists"
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depends on TMPFS
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select TMPFS_XATTR
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select FS_POSIX_ACL
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help
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POSIX Access Control Lists (ACLs) support additional access rights
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for users and groups beyond the standard owner/group/world scheme,
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and this option selects support for ACLs specifically for tmpfs
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filesystems.
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If you've selected TMPFS, it's possible that you'll also need
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this option as there are a number of Linux distros that require
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POSIX ACL support under /dev for certain features to work properly.
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For example, some distros need this feature for ALSA-related /dev
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files for sound to work properly. In short, if you're not sure,
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say Y.
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To learn more about Access Control Lists, visit the POSIX ACLs for
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Linux website <http://acl.bestbits.at/>.
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config TMPFS_XATTR
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bool "Tmpfs extended attributes"
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depends on TMPFS
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default n
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help
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Extended attributes are name:value pairs associated with inodes by
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the kernel or by users (see the attr(5) manual page, or visit
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<http://acl.bestbits.at/> for details).
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Currently this enables support for the trusted.* and
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security.* namespaces.
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You need this for POSIX ACL support on tmpfs.
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If unsure, say N.
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config HUGETLBFS
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bool "HugeTLB file system support"
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depends on X86 || IA64 || SPARC64 || (S390 && 64BIT) || \
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SYS_SUPPORTS_HUGETLBFS || BROKEN
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help
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hugetlbfs is a filesystem backing for HugeTLB pages, based on
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ramfs. For architectures that support it, say Y here and read
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<file:Documentation/vm/hugetlbpage.txt> for details.
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If unsure, say N.
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config HUGETLB_PAGE
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def_bool HUGETLBFS
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source "fs/configfs/Kconfig"
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endmenu
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menuconfig MISC_FILESYSTEMS
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bool "Miscellaneous filesystems"
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default y
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---help---
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Say Y here to get to see options for various miscellaneous
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filesystems, such as filesystems that came from other
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operating systems.
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This option alone does not add any kernel code.
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If you say N, all options in this submenu will be skipped and
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disabled; if unsure, say Y here.
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if MISC_FILESYSTEMS
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source "fs/adfs/Kconfig"
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source "fs/affs/Kconfig"
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source "fs/ecryptfs/Kconfig"
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source "fs/hfs/Kconfig"
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source "fs/hfsplus/Kconfig"
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source "fs/befs/Kconfig"
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source "fs/bfs/Kconfig"
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source "fs/efs/Kconfig"
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source "fs/jffs2/Kconfig"
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# UBIFS File system configuration
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source "fs/ubifs/Kconfig"
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source "fs/logfs/Kconfig"
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source "fs/cramfs/Kconfig"
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source "fs/squashfs/Kconfig"
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source "fs/freevxfs/Kconfig"
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source "fs/minix/Kconfig"
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source "fs/omfs/Kconfig"
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source "fs/hpfs/Kconfig"
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source "fs/qnx4/Kconfig"
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source "fs/qnx6/Kconfig"
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source "fs/romfs/Kconfig"
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source "fs/pstore/Kconfig"
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source "fs/sysv/Kconfig"
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source "fs/ufs/Kconfig"
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source "fs/exofs/Kconfig"
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source "fs/f2fs/Kconfig"
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source "fs/efivarfs/Kconfig"
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endif # MISC_FILESYSTEMS
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source "fs/exofs/Kconfig.ore"
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menuconfig NETWORK_FILESYSTEMS
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bool "Network File Systems"
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default y
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depends on NET
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---help---
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Say Y here to get to see options for network filesystems and
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filesystem-related networking code, such as NFS daemon and
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RPCSEC security modules.
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This option alone does not add any kernel code.
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If you say N, all options in this submenu will be skipped and
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disabled; if unsure, say Y here.
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if NETWORK_FILESYSTEMS
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source "fs/nfs/Kconfig"
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source "fs/nfsd/Kconfig"
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config GRACE_PERIOD
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tristate
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config LOCKD
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tristate
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depends on FILE_LOCKING
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select GRACE_PERIOD
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config LOCKD_V4
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bool
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depends on NFSD_V3 || NFS_V3
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depends on FILE_LOCKING
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default y
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config NFS_ACL_SUPPORT
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tristate
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select FS_POSIX_ACL
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config NFS_COMMON
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bool
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depends on NFSD || NFS_FS || LOCKD
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default y
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source "net/sunrpc/Kconfig"
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source "fs/ceph/Kconfig"
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source "fs/cifs/Kconfig"
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source "fs/ncpfs/Kconfig"
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source "fs/coda/Kconfig"
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source "fs/afs/Kconfig"
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source "fs/9p/Kconfig"
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endif # NETWORK_FILESYSTEMS
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source "fs/nls/Kconfig"
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source "fs/dlm/Kconfig"
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endmenu
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