diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/Locking | 4 | ||||
| -rw-r--r-- | Documentation/filesystems/devpts.txt | 132 | ||||
| -rw-r--r-- | Documentation/filesystems/files.txt | 6 | ||||
| -rw-r--r-- | Documentation/filesystems/ocfs2.txt | 6 | ||||
| -rw-r--r-- | Documentation/filesystems/proc.txt | 62 | ||||
| -rw-r--r-- | Documentation/filesystems/ramfs-rootfs-initramfs.txt | 12 | ||||
| -rw-r--r-- | Documentation/filesystems/ubifs.txt | 3 | ||||
| -rw-r--r-- | Documentation/filesystems/vfat.txt | 32 | ||||
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 5 | ||||
| -rw-r--r-- | Documentation/filesystems/xfs.txt | 4 | ||||
| -rw-r--r-- | Documentation/filesystems/xip.txt | 9 |
11 files changed, 241 insertions, 34 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 23d2f4460deb..cfbfa15a46ba 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -394,11 +394,10 @@ prototypes: unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); int (*check_flags)(int); - int (*dir_notify)(struct file *, unsigned long); }; locking rules: - All except ->poll() may block. + All may block. BKL llseek: no (see below) read: no @@ -424,7 +423,6 @@ sendfile: no sendpage: no get_unmapped_area: no check_flags: no -dir_notify: no ->llseek() locking has moved from llseek to the individual llseek implementations. If your fs is not using generic_file_llseek, you diff --git a/Documentation/filesystems/devpts.txt b/Documentation/filesystems/devpts.txt new file mode 100644 index 000000000000..68dffd87f9b7 --- /dev/null +++ b/Documentation/filesystems/devpts.txt @@ -0,0 +1,132 @@ + +To support containers, we now allow multiple instances of devpts filesystem, +such that indices of ptys allocated in one instance are independent of indices +allocated in other instances of devpts. + +To preserve backward compatibility, this support for multiple instances is +enabled only if: + + - CONFIG_DEVPTS_MULTIPLE_INSTANCES=y, and + - '-o newinstance' mount option is specified while mounting devpts + +IOW, devpts now supports both single-instance and multi-instance semantics. + +If CONFIG_DEVPTS_MULTIPLE_INSTANCES=n, there is no change in behavior and +this referred to as the "legacy" mode. In this mode, the new mount options +(-o newinstance and -o ptmxmode) will be ignored with a 'bogus option' message +on console. + +If CONFIG_DEVPTS_MULTIPLE_INSTANCES=y and devpts is mounted without the +'newinstance' option (as in current start-up scripts) the new mount binds +to the initial kernel mount of devpts. This mode is referred to as the +'single-instance' mode and the current, single-instance semantics are +preserved, i.e PTYs are common across the system. + +The only difference between this single-instance mode and the legacy mode +is the presence of new, '/dev/pts/ptmx' node with permissions 0000, which +can safely be ignored. + +If CONFIG_DEVPTS_MULTIPLE_INSTANCES=y and 'newinstance' option is specified, +the mount is considered to be in the multi-instance mode and a new instance +of the devpts fs is created. Any ptys created in this instance are independent +of ptys in other instances of devpts. Like in the single-instance mode, the +/dev/pts/ptmx node is present. To effectively use the multi-instance mode, +open of /dev/ptmx must be a redirected to '/dev/pts/ptmx' using a symlink or +bind-mount. + +Eg: A container startup script could do the following: + + $ chmod 0666 /dev/pts/ptmx + $ rm /dev/ptmx + $ ln -s pts/ptmx /dev/ptmx + $ ns_exec -cm /bin/bash + + # We are now in new container + + $ umount /dev/pts + $ mount -t devpts -o newinstance lxcpts /dev/pts + $ sshd -p 1234 + +where 'ns_exec -cm /bin/bash' calls clone() with CLONE_NEWNS flag and execs +/bin/bash in the child process. A pty created by the sshd is not visible in +the original mount of /dev/pts. + +User-space changes +------------------ + +In multi-instance mode (i.e '-o newinstance' mount option is specified at least +once), following user-space issues should be noted. + +1. If -o newinstance mount option is never used, /dev/pts/ptmx can be ignored + and no change is needed to system-startup scripts. + +2. To effectively use multi-instance mode (i.e -o newinstance is specified) + administrators or startup scripts should "redirect" open of /dev/ptmx to + /dev/pts/ptmx using either a bind mount or symlink. + + $ mount -t devpts -o newinstance devpts /dev/pts + + followed by either + + $ rm /dev/ptmx + $ ln -s pts/ptmx /dev/ptmx + $ chmod 666 /dev/pts/ptmx + or + $ mount -o bind /dev/pts/ptmx /dev/ptmx + +3. The '/dev/ptmx -> pts/ptmx' symlink is the preferred method since it + enables better error-reporting and treats both single-instance and + multi-instance mounts similarly. + + But this method requires that system-startup scripts set the mode of + /dev/pts/ptmx correctly (default mode is 0000). The scripts can set the + mode by, either + + - adding ptmxmode mount option to devpts entry in /etc/fstab, or + - using 'chmod 0666 /dev/pts/ptmx' + +4. If multi-instance mode mount is needed for containers, but the system + startup scripts have not yet been updated, container-startup scripts + should bind mount /dev/ptmx to /dev/pts/ptmx to avoid breaking single- + instance mounts. + + Or, in general, container-startup scripts should use: + + mount -t devpts -o newinstance -o ptmxmode=0666 devpts /dev/pts + if [ ! -L /dev/ptmx ]; then + mount -o bind /dev/pts/ptmx /dev/ptmx + fi + + When all devpts mounts are multi-instance, /dev/ptmx can permanently be + a symlink to pts/ptmx and the bind mount can be ignored. + +5. A multi-instance mount that is not accompanied by the /dev/ptmx to + /dev/pts/ptmx redirection would result in an unusable/unreachable pty. + + mount -t devpts -o newinstance lxcpts /dev/pts + + immediately followed by: + + open("/dev/ptmx") + + would create a pty, say /dev/pts/7, in the initial kernel mount. + But /dev/pts/7 would be invisible in the new mount. + +6. The permissions for /dev/pts/ptmx node should be specified when mounting + /dev/pts, using the '-o ptmxmode=%o' mount option (default is 0000). + + mount -t devpts -o newinstance -o ptmxmode=0644 devpts /dev/pts + + The permissions can be later be changed as usual with 'chmod'. + + chmod 666 /dev/pts/ptmx + +7. A mount of devpts without the 'newinstance' option results in binding to + initial kernel mount. This behavior while preserving legacy semantics, + does not provide strict isolation in a container environment. i.e by + mounting devpts without the 'newinstance' option, a container could + get visibility into the 'host' or root container's devpts. + + To workaround this and have strict isolation, all mounts of devpts, + including the mount in the root container, should use the newinstance + option. diff --git a/Documentation/filesystems/files.txt b/Documentation/filesystems/files.txt index bb0142f61084..ac2facc50d2a 100644 --- a/Documentation/filesystems/files.txt +++ b/Documentation/filesystems/files.txt @@ -76,13 +76,13 @@ the fdtable structure - 5. Handling of the file structures is special. Since the look-up of the fd (fget()/fget_light()) are lock-free, it is possible that look-up may race with the last put() operation on the - file structure. This is avoided using atomic_inc_not_zero() + file structure. This is avoided using atomic_long_inc_not_zero() on ->f_count : rcu_read_lock(); file = fcheck_files(files, fd); if (file) { - if (atomic_inc_not_zero(&file->f_count)) + if (atomic_long_inc_not_zero(&file->f_count)) *fput_needed = 1; else /* Didn't get the reference, someone's freed */ @@ -92,7 +92,7 @@ the fdtable structure - .... return file; - atomic_inc_not_zero() detects if refcounts is already zero or + atomic_long_inc_not_zero() detects if refcounts is already zero or goes to zero during increment. If it does, we fail fget()/fget_light(). diff --git a/Documentation/filesystems/ocfs2.txt b/Documentation/filesystems/ocfs2.txt index 4340cc825796..c2a0871280a0 100644 --- a/Documentation/filesystems/ocfs2.txt +++ b/Documentation/filesystems/ocfs2.txt @@ -28,13 +28,9 @@ Manish Singh <[email protected]> Caveats ======= Features which OCFS2 does not support yet: - - extended attributes - quotas - - cluster aware flock - - cluster aware lockf - Directory change notification (F_NOTIFY) - Distributed Caching (F_SETLEASE/F_GETLEASE/break_lease) - - POSIX ACLs Mount options ============= @@ -82,3 +78,5 @@ inode64 Indicates that Ocfs2 is allowed to create inodes at bits of significance. user_xattr (*) Enables Extended User Attributes. nouser_xattr Disables Extended User Attributes. +acl Enables POSIX Access Control Lists support. +noacl (*) Disables POSIX Access Control Lists support. diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index bcceb99b81dd..32e94635484f 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -44,6 +44,7 @@ Table of Contents 2.14 /proc/<pid>/io - Display the IO accounting fields 2.15 /proc/<pid>/coredump_filter - Core dump filtering settings 2.16 /proc/<pid>/mountinfo - Information about mounts + 2.17 /proc/sys/fs/epoll - Configuration options for the epoll interface ------------------------------------------------------------------------------ Preface @@ -1338,10 +1339,13 @@ nmi_watchdog Enables/Disables the NMI watchdog on x86 systems. When the value is non-zero the NMI watchdog is enabled and will continuously test all online cpus to -determine whether or not they are still functioning properly. +determine whether or not they are still functioning properly. Currently, +passing "nmi_watchdog=" parameter at boot time is required for this function +to work. -Because the NMI watchdog shares registers with oprofile, by disabling the NMI -watchdog, oprofile may have more registers to utilize. +If LAPIC NMI watchdog method is in use (nmi_watchdog=2 kernel parameter), the +NMI watchdog shares registers with oprofile. By disabling the NMI watchdog, +oprofile may have more registers to utilize. msgmni ------ @@ -1381,6 +1385,15 @@ swapcache reclaim. Decreasing vfs_cache_pressure causes the kernel to prefer to retain dentry and inode caches. Increasing vfs_cache_pressure beyond 100 causes the kernel to prefer to reclaim dentries and inodes. +dirty_background_bytes +---------------------- + +Contains the amount of dirty memory at which the pdflush background writeback +daemon will start writeback. + +If dirty_background_bytes is written, dirty_background_ratio becomes a function +of its value (dirty_background_bytes / the amount of dirtyable system memory). + dirty_background_ratio ---------------------- @@ -1389,14 +1402,29 @@ pages + file cache, not including locked pages and HugePages), the number of pages at which the pdflush background writeback daemon will start writing out dirty data. +If dirty_background_ratio is written, dirty_background_bytes becomes a function +of its value (dirty_background_ratio * the amount of dirtyable system memory). + +dirty_bytes +----------- + +Contains the amount of dirty memory at which a process generating disk writes +will itself start writeback. + +If dirty_bytes is written, dirty_ratio becomes a function of its value +(dirty_bytes / the amount of dirtyable system memory). + dirty_ratio ------------------ +----------- Contains, as a percentage of the dirtyable system memory (free pages + mapped pages + file cache, not including locked pages and HugePages), the number of pages at which a process which is generating disk writes will itself start writing out dirty data. +If dirty_ratio is written, dirty_bytes becomes a function of its value +(dirty_ratio * the amount of dirtyable system memory). + dirty_writeback_centisecs ------------------------- @@ -2483,4 +2511,30 @@ For more information on mount propagation see: Documentation/filesystems/sharedsubtree.txt +2.17 /proc/sys/fs/epoll - Configuration options for the epoll interface +-------------------------------------------------------- + +This directory contains configuration options for the epoll(7) interface. + +max_user_instances +------------------ + +This is the maximum number of epoll file descriptors that a single user can +have open at a given time. The default value is 128, and should be enough +for normal users. + +max_user_watches +---------------- + +Every epoll file descriptor can store a number of files to be monitored +for event readiness. Each one of these monitored files constitutes a "watch". +This configuration option sets the maximum number of "watches" that are +allowed for each user. +Each "watch" costs roughly 90 bytes on a 32bit kernel, and roughly 160 bytes +on a 64bit one. +The current default value for max_user_watches is the 1/32 of the available +low memory, divided for the "watch" cost in bytes. + + ------------------------------------------------------------------------------ + diff --git a/Documentation/filesystems/ramfs-rootfs-initramfs.txt b/Documentation/filesystems/ramfs-rootfs-initramfs.txt index 62fe9b1e0890..a8273d5fad20 100644 --- a/Documentation/filesystems/ramfs-rootfs-initramfs.txt +++ b/Documentation/filesystems/ramfs-rootfs-initramfs.txt @@ -130,12 +130,12 @@ The 2.6 kernel build process always creates a gzipped cpio format initramfs archive and links it into the resulting kernel binary. By default, this archive is empty (consuming 134 bytes on x86). -The config option CONFIG_INITRAMFS_SOURCE (for some reason buried under -devices->block devices in menuconfig, and living in usr/Kconfig) can be used -to specify a source for the initramfs archive, which will automatically be -incorporated into the resulting binary. This option can point to an existing -gzipped cpio archive, a directory containing files to be archived, or a text -file specification such as the following example: +The config option CONFIG_INITRAMFS_SOURCE (in General Setup in menuconfig, +and living in usr/Kconfig) can be used to specify a source for the +initramfs archive, which will automatically be incorporated into the +resulting binary. This option can point to an existing gzipped cpio +archive, a directory containing files to be archived, or a text file +specification such as the following example: dir /dev 755 0 0 nod /dev/console 644 0 0 c 5 1 diff --git a/Documentation/filesystems/ubifs.txt b/Documentation/filesystems/ubifs.txt index dd84ea3c10da..84da2a4ba25a 100644 --- a/Documentation/filesystems/ubifs.txt +++ b/Documentation/filesystems/ubifs.txt @@ -95,6 +95,9 @@ no_chk_data_crc skip checking of CRCs on data nodes in order to of this option is that corruption of the contents of a file can go unnoticed. chk_data_crc (*) do not skip checking CRCs on data nodes +compr=none override default compressor and set it to "none" +compr=lzo override default compressor and set it to "lzo" +compr=zlib override default compressor and set it to "zlib" Quick usage instructions diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt index bbac4f1d9056..3a5ddc96901a 100644 --- a/Documentation/filesystems/vfat.txt +++ b/Documentation/filesystems/vfat.txt @@ -8,6 +8,12 @@ if you want to format from within Linux. VFAT MOUNT OPTIONS ---------------------------------------------------------------------- +uid=### -- Set the owner of all files on this filesystem. + The default is the uid of current process. + +gid=### -- Set the group of all files on this filesystem. + The default is the gid of current process. + umask=### -- The permission mask (for files and directories, see umask(1)). The default is the umask of current process. @@ -36,7 +42,7 @@ codepage=### -- Sets the codepage number for converting to shortname characters on FAT filesystem. By default, FAT_DEFAULT_CODEPAGE setting is used. -iocharset=name -- Character set to use for converting between the +iocharset=<name> -- Character set to use for converting between the encoding is used for user visible filename and 16 bit Unicode characters. Long filenames are stored on disk in Unicode format, but Unix for the most part doesn't @@ -86,6 +92,8 @@ check=s|r|n -- Case sensitivity checking setting. r: relaxed, case insensitive n: normal, default setting, currently case insensitive +nocase -- This was deprecated for vfat. Use shortname=win95 instead. + shortname=lower|win95|winnt|mixed -- Shortname display/create setting. lower: convert to lowercase for display, @@ -99,11 +107,31 @@ shortname=lower|win95|winnt|mixed tz=UTC -- Interpret timestamps as UTC rather than local time. This option disables the conversion of timestamps between local time (as used by Windows on FAT) and UTC - (which Linux uses internally). This is particuluarly + (which Linux uses internally). This is particularly useful when mounting devices (like digital cameras) that are set to UTC in order to avoid the pitfalls of local time. +showexec -- If set, the execute permission bits of the file will be + allowed only if the extension part of the name is .EXE, + .COM, or .BAT. Not set by default. + +debug -- Can be set, but unused by the current implementation. + +sys_immutable -- If set, ATTR_SYS attribute on FAT is handled as + IMMUTABLE flag on Linux. Not set by default. + +flush -- If set, the filesystem will try to flush to disk more + early than normal. Not set by default. + +rodir -- FAT has the ATTR_RO (read-only) attribute. But on Windows, + the ATTR_RO of the directory will be just ignored actually, + and is used by only applications as flag. E.g. it's setted + for the customized folder. + + If you want to use ATTR_RO as read-only flag even for + the directory, set this option. + <bool>: 0,1,yes,no,true,false TODO diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index 5579bda58a6d..ef19afa186a9 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -733,7 +733,6 @@ struct file_operations { ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int); unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); int (*check_flags)(int); - int (*dir_notify)(struct file *filp, unsigned long arg); int (*flock) (struct file *, int, struct file_lock *); ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, size_t, unsigned int); ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned int); @@ -800,8 +799,6 @@ otherwise noted. check_flags: called by the fcntl(2) system call for F_SETFL command - dir_notify: called by the fcntl(2) system call for F_NOTIFY command - flock: called by the flock(2) system call splice_write: called by the VFS to splice data from a pipe to a file. This @@ -931,7 +928,7 @@ manipulate dentries: d_lookup: look up a dentry given its parent and path name component It looks up the child of that given name from the dcache hash table. If it is found, the reference count is incremented - and the dentry is returned. The caller must use d_put() + and the dentry is returned. The caller must use dput() to free the dentry when it finishes using it. For further information on dentry locking, please refer to the document diff --git a/Documentation/filesystems/xfs.txt b/Documentation/filesystems/xfs.txt index 0a1668ba2600..9878f50d6ed6 100644 --- a/Documentation/filesystems/xfs.txt +++ b/Documentation/filesystems/xfs.txt @@ -229,10 +229,6 @@ The following sysctls are available for the XFS filesystem: ISGID bit is cleared if the irix_sgid_inherit compatibility sysctl is set. - fs.xfs.restrict_chown (Min: 0 Default: 1 Max: 1) - Controls whether unprivileged users can use chown to "give away" - a file to another user. - fs.xfs.inherit_sync (Min: 0 Default: 1 Max: 1) Setting this to "1" will cause the "sync" flag set by the xfs_io(8) chattr command on a directory to be diff --git a/Documentation/filesystems/xip.txt b/Documentation/filesystems/xip.txt index 3cc4010521a0..0466ee569278 100644 --- a/Documentation/filesystems/xip.txt +++ b/Documentation/filesystems/xip.txt @@ -39,10 +39,11 @@ The block device operation is optional, these block devices support it as of today: - dcssblk: s390 dcss block device driver -An address space operation named get_xip_page is used to retrieve reference -to a struct page. To address the target page, a reference to an address_space, -and a sector number is provided. A 3rd argument indicates whether the -function should allocate blocks if needed. +An address space operation named get_xip_mem is used to retrieve references +to a page frame number and a kernel address. To obtain these values a reference +to an address_space is provided. This function assigns values to the kmem and +pfn parameters. The third argument indicates whether the function should allocate +blocks if needed. This address space operation is mutually exclusive with readpage&writepage that do page cache read/write operations. |