diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/erofs.rst | 12 | ||||
| -rw-r--r-- | Documentation/filesystems/ext4/orphan.rst | 44 | ||||
| -rw-r--r-- | Documentation/filesystems/f2fs.rst | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/fscrypt.rst | 83 | ||||
| -rw-r--r-- | Documentation/filesystems/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/filesystems/locks.rst | 17 | ||||
| -rw-r--r-- | Documentation/filesystems/netfs_library.rst | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/nfs/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/filesystems/nfs/reexport.rst | 113 | ||||
| -rw-r--r-- | Documentation/filesystems/ntfs3.rst | 141 | ||||
| -rw-r--r-- | Documentation/filesystems/proc.rst | 26 |
11 files changed, 296 insertions, 146 deletions
diff --git a/Documentation/filesystems/erofs.rst b/Documentation/filesystems/erofs.rst index b97579b7d8fb..01df283c7d04 100644 --- a/Documentation/filesystems/erofs.rst +++ b/Documentation/filesystems/erofs.rst @@ -19,9 +19,10 @@ It is designed as a better filesystem solution for the following scenarios: immutable and bit-for-bit identical to the official golden image for their releases due to security and other considerations and - - hope to save some extra storage space with guaranteed end-to-end performance - by using reduced metadata and transparent file compression, especially - for those embedded devices with limited memory (ex, smartphone); + - hope to minimize extra storage space with guaranteed end-to-end performance + by using compact layout, transparent file compression and direct access, + especially for those embedded devices with limited memory and high-density + hosts with numerous containers; Here is the main features of EROFS: @@ -51,7 +52,9 @@ Here is the main features of EROFS: - Support POSIX.1e ACLs by using xattrs; - Support transparent data compression as an option: - LZ4 algorithm with the fixed-sized output compression for high performance. + LZ4 algorithm with the fixed-sized output compression for high performance; + + - Multiple device support for multi-layer container images. The following git tree provides the file system user-space tools under development (ex, formatting tool mkfs.erofs): @@ -87,6 +90,7 @@ cache_strategy=%s Select a strategy for cached decompression from now on: dax={always,never} Use direct access (no page cache). See Documentation/filesystems/dax.rst. dax A legacy option which is an alias for ``dax=always``. +device=%s Specify a path to an extra device to be used together. =================== ========================================================= On-disk details diff --git a/Documentation/filesystems/ext4/orphan.rst b/Documentation/filesystems/ext4/orphan.rst index bb19ecd1b626..03cca178864b 100644 --- a/Documentation/filesystems/ext4/orphan.rst +++ b/Documentation/filesystems/ext4/orphan.rst @@ -12,41 +12,31 @@ track the inode as orphan so that in case of crash extra blocks allocated to the file get truncated. Traditionally ext4 tracks orphan inodes in a form of single linked list where -superblock contains the inode number of the last orphan inode (s\_last\_orphan +superblock contains the inode number of the last orphan inode (s_last_orphan field) and then each inode contains inode number of the previously orphaned -inode (we overload i\_dtime inode field for this). However this filesystem +inode (we overload i_dtime inode field for this). However this filesystem global single linked list is a scalability bottleneck for workloads that result in heavy creation of orphan inodes. When orphan file feature -(COMPAT\_ORPHAN\_FILE) is enabled, the filesystem has a special inode -(referenced from the superblock through s\_orphan_file_inum) with several +(COMPAT_ORPHAN_FILE) is enabled, the filesystem has a special inode +(referenced from the superblock through s_orphan_file_inum) with several blocks. Each of these blocks has a structure: -.. list-table:: - :widths: 8 8 24 40 - :header-rows: 1 - - * - Offset - - Type - - Name - - Description - * - 0x0 - - Array of \_\_le32 entries - - Orphan inode entries - - Each \_\_le32 entry is either empty (0) or it contains inode number of - an orphan inode. - * - blocksize - 8 - - \_\_le32 - - ob\_magic - - Magic value stored in orphan block tail (0x0b10ca04) - * - blocksize - 4 - - \_\_le32 - - ob\_checksum - - Checksum of the orphan block. +============= ================ =============== =============================== +Offset Type Name Description +============= ================ =============== =============================== +0x0 Array of Orphan inode Each __le32 entry is either + __le32 entries entries empty (0) or it contains + inode number of an orphan + inode. +blocksize-8 __le32 ob_magic Magic value stored in orphan + block tail (0x0b10ca04) +blocksize-4 __le32 ob_checksum Checksum of the orphan block. +============= ================ =============== =============================== When a filesystem with orphan file feature is writeably mounted, we set -RO\_COMPAT\_ORPHAN\_PRESENT feature in the superblock to indicate there may +RO_COMPAT_ORPHAN_PRESENT feature in the superblock to indicate there may be valid orphan entries. In case we see this feature when mounting the filesystem, we read the whole orphan file and process all orphan inodes found there as usual. When cleanly unmounting the filesystem we remove the -RO\_COMPAT\_ORPHAN\_PRESENT feature to avoid unnecessary scanning of the orphan +RO_COMPAT_ORPHAN_PRESENT feature to avoid unnecessary scanning of the orphan file and also make the filesystem fully compatible with older kernels. diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst index 6954c04753ad..d7b84695f56a 100644 --- a/Documentation/filesystems/f2fs.rst +++ b/Documentation/filesystems/f2fs.rst @@ -302,7 +302,7 @@ compress_extension=%s Support adding specified extension, so that f2fs can enab For other files, we can still enable compression via ioctl. Note that, there is one reserved special extension '*', it can be set to enable compression for all files. -nocompress_extension=%s Support adding specified extension, so that f2fs can disable +nocompress_extension=%s Support adding specified extension, so that f2fs can disable compression on those corresponding files, just contrary to compression extension. If you know exactly which files cannot be compressed, you can use this. The same extension name can't appear in both compress and nocompress diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst index 0eb799d9d05a..4d5d50dca65c 100644 --- a/Documentation/filesystems/fscrypt.rst +++ b/Documentation/filesystems/fscrypt.rst @@ -77,11 +77,11 @@ Side-channel attacks fscrypt is only resistant to side-channel attacks, such as timing or electromagnetic attacks, to the extent that the underlying Linux -Cryptographic API algorithms are. If a vulnerable algorithm is used, -such as a table-based implementation of AES, it may be possible for an -attacker to mount a side channel attack against the online system. -Side channel attacks may also be mounted against applications -consuming decrypted data. +Cryptographic API algorithms or inline encryption hardware are. If a +vulnerable algorithm is used, such as a table-based implementation of +AES, it may be possible for an attacker to mount a side channel attack +against the online system. Side channel attacks may also be mounted +against applications consuming decrypted data. Unauthorized file access ~~~~~~~~~~~~~~~~~~~~~~~~ @@ -176,11 +176,11 @@ Master Keys Each encrypted directory tree is protected by a *master key*. Master keys can be up to 64 bytes long, and must be at least as long as the -greater of the key length needed by the contents and filenames -encryption modes being used. For example, if AES-256-XTS is used for -contents encryption, the master key must be 64 bytes (512 bits). Note -that the XTS mode is defined to require a key twice as long as that -required by the underlying block cipher. +greater of the security strength of the contents and filenames +encryption modes being used. For example, if any AES-256 mode is +used, the master key must be at least 256 bits, i.e. 32 bytes. A +stricter requirement applies if the key is used by a v1 encryption +policy and AES-256-XTS is used; such keys must be 64 bytes. To "unlock" an encrypted directory tree, userspace must provide the appropriate master key. There can be any number of master keys, each @@ -1135,6 +1135,50 @@ where applications may later write sensitive data. It is recommended that systems implementing a form of "verified boot" take advantage of this by validating all top-level encryption policies prior to access. +Inline encryption support +========================= + +By default, fscrypt uses the kernel crypto API for all cryptographic +operations (other than HKDF, which fscrypt partially implements +itself). The kernel crypto API supports hardware crypto accelerators, +but only ones that work in the traditional way where all inputs and +outputs (e.g. plaintexts and ciphertexts) are in memory. fscrypt can +take advantage of such hardware, but the traditional acceleration +model isn't particularly efficient and fscrypt hasn't been optimized +for it. + +Instead, many newer systems (especially mobile SoCs) have *inline +encryption hardware* that can encrypt/decrypt data while it is on its +way to/from the storage device. Linux supports inline encryption +through a set of extensions to the block layer called *blk-crypto*. +blk-crypto allows filesystems to attach encryption contexts to bios +(I/O requests) to specify how the data will be encrypted or decrypted +in-line. For more information about blk-crypto, see +:ref:`Documentation/block/inline-encryption.rst <inline_encryption>`. + +On supported filesystems (currently ext4 and f2fs), fscrypt can use +blk-crypto instead of the kernel crypto API to encrypt/decrypt file +contents. To enable this, set CONFIG_FS_ENCRYPTION_INLINE_CRYPT=y in +the kernel configuration, and specify the "inlinecrypt" mount option +when mounting the filesystem. + +Note that the "inlinecrypt" mount option just specifies to use inline +encryption when possible; it doesn't force its use. fscrypt will +still fall back to using the kernel crypto API on files where the +inline encryption hardware doesn't have the needed crypto capabilities +(e.g. support for the needed encryption algorithm and data unit size) +and where blk-crypto-fallback is unusable. (For blk-crypto-fallback +to be usable, it must be enabled in the kernel configuration with +CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK=y.) + +Currently fscrypt always uses the filesystem block size (which is +usually 4096 bytes) as the data unit size. Therefore, it can only use +inline encryption hardware that supports that data unit size. + +Inline encryption doesn't affect the ciphertext or other aspects of +the on-disk format, so users may freely switch back and forth between +using "inlinecrypt" and not using "inlinecrypt". + Implementation details ====================== @@ -1184,6 +1228,13 @@ keys`_ and `DIRECT_KEY policies`_. Data path changes ----------------- +When inline encryption is used, filesystems just need to associate +encryption contexts with bios to specify how the block layer or the +inline encryption hardware will encrypt/decrypt the file contents. + +When inline encryption isn't used, filesystems must encrypt/decrypt +the file contents themselves, as described below: + For the read path (->readpage()) of regular files, filesystems can read the ciphertext into the page cache and decrypt it in-place. The page lock must be held until decryption has finished, to prevent the @@ -1197,18 +1248,6 @@ buffer. Some filesystems, such as UBIFS, already use temporary buffers regardless of encryption. Other filesystems, such as ext4 and F2FS, have to allocate bounce pages specially for encryption. -Fscrypt is also able to use inline encryption hardware instead of the -kernel crypto API for en/decryption of file contents. When possible, -and if directed to do so (by specifying the 'inlinecrypt' mount option -for an ext4/F2FS filesystem), it adds encryption contexts to bios and -uses blk-crypto to perform the en/decryption instead of making use of -the above read/write path changes. Of course, even if directed to -make use of inline encryption, fscrypt will only be able to do so if -either hardware inline encryption support is available for the -selected encryption algorithm or CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK -is selected. If neither is the case, fscrypt will fall back to using -the above mentioned read/write path changes for en/decryption. - Filename hashing and encoding ----------------------------- diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst index c0ad233963ae..bee63d42e5ec 100644 --- a/Documentation/filesystems/index.rst +++ b/Documentation/filesystems/index.rst @@ -29,7 +29,6 @@ algorithms work. fiemap files locks - mandatory-locking mount_api quota seq_file diff --git a/Documentation/filesystems/locks.rst b/Documentation/filesystems/locks.rst index c5ae858b1aac..26429317dbbc 100644 --- a/Documentation/filesystems/locks.rst +++ b/Documentation/filesystems/locks.rst @@ -57,16 +57,9 @@ fcntl(), with all the problems that implies. 1.3 Mandatory Locking As A Mount Option --------------------------------------- -Mandatory locking, as described in -'Documentation/filesystems/mandatory-locking.rst' was prior to this release a -general configuration option that was valid for all mounted filesystems. This -had a number of inherent dangers, not the least of which was the ability to -freeze an NFS server by asking it to read a file for which a mandatory lock -existed. - -From this release of the kernel, mandatory locking can be turned on and off -on a per-filesystem basis, using the mount options 'mand' and 'nomand'. -The default is to disallow mandatory locking. The intention is that -mandatory locking only be enabled on a local filesystem as the specific need -arises. +Mandatory locking was prior to this release a general configuration option +that was valid for all mounted filesystems. This had a number of inherent +dangers, not the least of which was the ability to freeze an NFS server by +asking it to read a file for which a mandatory lock existed. +Such option was dropped in Kernel v5.14. diff --git a/Documentation/filesystems/netfs_library.rst b/Documentation/filesystems/netfs_library.rst index 57a641847818..bb68d39f03b7 100644 --- a/Documentation/filesystems/netfs_library.rst +++ b/Documentation/filesystems/netfs_library.rst @@ -524,3 +524,5 @@ Note that these methods are passed a pointer to the cache resource structure, not the read request structure as they could be used in other situations where there isn't a read request structure as well, such as writing dirty data to the cache. + +.. kernel-doc:: include/linux/netfs.h diff --git a/Documentation/filesystems/nfs/index.rst b/Documentation/filesystems/nfs/index.rst index 65805624e39b..288d8ddb2bc6 100644 --- a/Documentation/filesystems/nfs/index.rst +++ b/Documentation/filesystems/nfs/index.rst @@ -11,3 +11,4 @@ NFS rpc-server-gss nfs41-server knfsd-stats + reexport diff --git a/Documentation/filesystems/nfs/reexport.rst b/Documentation/filesystems/nfs/reexport.rst new file mode 100644 index 000000000000..ff9ae4a46530 --- /dev/null +++ b/Documentation/filesystems/nfs/reexport.rst @@ -0,0 +1,113 @@ +Reexporting NFS filesystems +=========================== + +Overview +-------- + +It is possible to reexport an NFS filesystem over NFS. However, this +feature comes with a number of limitations. Before trying it, we +recommend some careful research to determine whether it will work for +your purposes. + +A discussion of current known limitations follows. + +"fsid=" required, crossmnt broken +--------------------------------- + +We require the "fsid=" export option on any reexport of an NFS +filesystem. You can use "uuidgen -r" to generate a unique argument. + +The "crossmnt" export does not propagate "fsid=", so it will not allow +traversing into further nfs filesystems; if you wish to export nfs +filesystems mounted under the exported filesystem, you'll need to export +them explicitly, assigning each its own unique "fsid= option. + +Reboot recovery +--------------- + +The NFS protocol's normal reboot recovery mechanisms don't work for the +case when the reexport server reboots. Clients will lose any locks +they held before the reboot, and further IO will result in errors. +Closing and reopening files should clear the errors. + +Filehandle limits +----------------- + +If the original server uses an X byte filehandle for a given object, the +reexport server's filehandle for the reexported object will be X+22 +bytes, rounded up to the nearest multiple of four bytes. + +The result must fit into the RFC-mandated filehandle size limits: + ++-------+-----------+ +| NFSv2 | 32 bytes | ++-------+-----------+ +| NFSv3 | 64 bytes | ++-------+-----------+ +| NFSv4 | 128 bytes | ++-------+-----------+ + +So, for example, you will only be able to reexport a filesystem over +NFSv2 if the original server gives you filehandles that fit in 10 +bytes--which is unlikely. + +In general there's no way to know the maximum filehandle size given out +by an NFS server without asking the server vendor. + +But the following table gives a few examples. The first column is the +typical length of the filehandle from a Linux server exporting the given +filesystem, the second is the length after that nfs export is reexported +by another Linux host: + ++--------+-------------------+----------------+ +| | filehandle length | after reexport | ++========+===================+================+ +| ext4: | 28 bytes | 52 bytes | ++--------+-------------------+----------------+ +| xfs: | 32 bytes | 56 bytes | ++--------+-------------------+----------------+ +| btrfs: | 40 bytes | 64 bytes | ++--------+-------------------+----------------+ + +All will therefore fit in an NFSv3 or NFSv4 filehandle after reexport, +but none are reexportable over NFSv2. + +Linux server filehandles are a bit more complicated than this, though; +for example: + + - The (non-default) "subtreecheck" export option generally + requires another 4 to 8 bytes in the filehandle. + - If you export a subdirectory of a filesystem (instead of + exporting the filesystem root), that also usually adds 4 to 8 + bytes. + - If you export over NFSv2, knfsd usually uses a shorter + filesystem identifier that saves 8 bytes. + - The root directory of an export uses a filehandle that is + shorter. + +As you can see, the 128-byte NFSv4 filehandle is large enough that +you're unlikely to have trouble using NFSv4 to reexport any filesystem +exported from a Linux server. In general, if the original server is +something that also supports NFSv3, you're *probably* OK. Re-exporting +over NFSv3 may be dicier, and reexporting over NFSv2 will probably +never work. + +For more details of Linux filehandle structure, the best reference is +the source code and comments; see in particular: + + - include/linux/exportfs.h:enum fid_type + - include/uapi/linux/nfsd/nfsfh.h:struct nfs_fhbase_new + - fs/nfsd/nfsfh.c:set_version_and_fsid_type + - fs/nfs/export.c:nfs_encode_fh + +Open DENY bits ignored +---------------------- + +NFS since NFSv4 supports ALLOW and DENY bits taken from Windows, which +allow you, for example, to open a file in a mode which forbids other +read opens or write opens. The Linux client doesn't use them, and the +server's support has always been incomplete: they are enforced only +against other NFS users, not against processes accessing the exported +filesystem locally. A reexport server will also not pass them along to +the original server, so they will not be enforced between clients of +different reexport servers. diff --git a/Documentation/filesystems/ntfs3.rst b/Documentation/filesystems/ntfs3.rst index ffe9ea0c1499..d67ccd22c63b 100644 --- a/Documentation/filesystems/ntfs3.rst +++ b/Documentation/filesystems/ntfs3.rst @@ -4,103 +4,112 @@ NTFS3 ===== - Summary and Features ==================== -NTFS3 is fully functional NTFS Read-Write driver. The driver works with -NTFS versions up to 3.1, normal/compressed/sparse files -and journal replaying. File system type to use on mount is 'ntfs3'. +NTFS3 is fully functional NTFS Read-Write driver. The driver works with NTFS +versions up to 3.1. File system type to use on mount is *ntfs3*. - This driver implements NTFS read/write support for normal, sparse and compressed files. -- Supports native journal replaying; -- Supports extended attributes - Predefined extended attributes: - - 'system.ntfs_security' gets/sets security - descriptor (SECURITY_DESCRIPTOR_RELATIVE) - - 'system.ntfs_attrib' gets/sets ntfs file/dir attributes. - Note: applied to empty files, this allows to switch type between - sparse(0x200), compressed(0x800) and normal; +- Supports native journal replaying. - Supports NFS export of mounted NTFS volumes. +- Supports extended attributes. Predefined extended attributes: + + - *system.ntfs_security* gets/sets security + + Descriptor: SECURITY_DESCRIPTOR_RELATIVE + + - *system.ntfs_attrib* gets/sets ntfs file/dir attributes. + + Note: Applied to empty files, this allows to switch type between + sparse(0x200), compressed(0x800) and normal. Mount Options ============= The list below describes mount options supported by NTFS3 driver in addition to -generic ones. +generic ones. You can use every mount option with **no** option. If it is in +this table marked with no it means default is without **no**. -=============================================================================== +.. flat-table:: + :widths: 1 5 + :fill-cells: -nls=name This option informs the driver how to interpret path - strings and translate them to Unicode and back. If - this option is not set, the default codepage will be - used (CONFIG_NLS_DEFAULT). - Examples: - 'nls=utf8' + * - iocharset=name + - This option informs the driver how to interpret path strings and + translate them to Unicode and back. If this option is not set, the + default codepage will be used (CONFIG_NLS_DEFAULT). -uid= -gid= -umask= Controls the default permissions for files/directories created - after the NTFS volume is mounted. + Example: iocharset=utf8 -fmask= -dmask= Instead of specifying umask which applies both to - files and directories, fmask applies only to files and - dmask only to directories. + * - uid= + - :rspan:`1` + * - gid= -nohidden Files with the Windows-specific HIDDEN (FILE_ATTRIBUTE_HIDDEN) - attribute will not be shown under Linux. + * - umask= + - Controls the default permissions for files/directories created after + the NTFS volume is mounted. -sys_immutable Files with the Windows-specific SYSTEM - (FILE_ATTRIBUTE_SYSTEM) attribute will be marked as system - immutable files. + * - dmask= + - :rspan:`1` Instead of specifying umask which applies both to files and + directories, fmask applies only to files and dmask only to directories. + * - fmask= -discard Enable support of the TRIM command for improved performance - on delete operations, which is recommended for use with the - solid-state drives (SSD). + * - noacsrules + - "No access rules" mount option sets access rights for files/folders to + 777 and owner/group to root. This mount option absorbs all other + permissions. -force Forces the driver to mount partitions even if 'dirty' flag - (volume dirty) is set. Not recommended for use. + - Permissions change for files/folders will be reported as successful, + but they will remain 777. -sparse Create new files as "sparse". + - Owner/group change will be reported as successful, butthey will stay + as root. -showmeta Use this parameter to show all meta-files (System Files) on - a mounted NTFS partition. - By default, all meta-files are hidden. + * - nohidden + - Files with the Windows-specific HIDDEN (FILE_ATTRIBUTE_HIDDEN) attribute + will not be shown under Linux. -prealloc Preallocate space for files excessively when file size is - increasing on writes. Decreases fragmentation in case of - parallel write operations to different files. + * - sys_immutable + - Files with the Windows-specific SYSTEM (FILE_ATTRIBUTE_SYSTEM) attribute + will be marked as system immutable files. -no_acs_rules "No access rules" mount option sets access rights for - files/folders to 777 and owner/group to root. This mount - option absorbs all other permissions: - - permissions change for files/folders will be reported - as successful, but they will remain 777; - - owner/group change will be reported as successful, but - they will stay as root + * - discard + - Enable support of the TRIM command for improved performance on delete + operations, which is recommended for use with the solid-state drives + (SSD). -acl Support POSIX ACLs (Access Control Lists). Effective if - supported by Kernel. Not to be confused with NTFS ACLs. - The option specified as acl enables support for POSIX ACLs. + * - force + - Forces the driver to mount partitions even if volume is marked dirty. + Not recommended for use. -noatime All files and directories will not update their last access - time attribute if a partition is mounted with this parameter. - This option can speed up file system operation. + * - sparse + - Create new files as sparse. -=============================================================================== + * - showmeta + - Use this parameter to show all meta-files (System Files) on a mounted + NTFS partition. By default, all meta-files are hidden. -ToDo list -========= + * - prealloc + - Preallocate space for files excessively when file size is increasing on + writes. Decreases fragmentation in case of parallel write operations to + different files. -- Full journaling support (currently journal replaying is supported) over JBD. + * - acl + - Support POSIX ACLs (Access Control Lists). Effective if supported by + Kernel. Not to be confused with NTFS ACLs. The option specified as acl + enables support for POSIX ACLs. +Todo list +========= +- Full journaling support over JBD. Currently journal replaying is supported + which is not necessarily as effectice as JBD would be. References ========== -https://www.paragon-software.com/home/ntfs-linux-professional/ - - Commercial version of the NTFS driver for Linux. +- Commercial version of the NTFS driver for Linux. + https://www.paragon-software.com/home/ntfs-linux-professional/ -almaz.alexandrovich@paragon-software.com - - Direct e-mail address for feedback and requests on the NTFS3 implementation. +- Direct e-mail address for feedback and requests on the NTFS3 implementation. + almaz.alexandrovich@paragon-software.com diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 042c418f4090..8d7f141c6fc7 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -1857,19 +1857,19 @@ For example:: This file contains lines of the form:: 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue - (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) - - (1) mount ID: unique identifier of the mount (may be reused after umount) - (2) parent ID: ID of parent (or of self for the top of the mount tree) - (3) major:minor: value of st_dev for files on filesystem - (4) root: root of the mount within the filesystem - (5) mount point: mount point relative to the process's root - (6) mount options: per mount options - (7) optional fields: zero or more fields of the form "tag[:value]" - (8) separator: marks the end of the optional fields - (9) filesystem type: name of filesystem of the form "type[.subtype]" - (10) mount source: filesystem specific information or "none" - (11) super options: per super block options + (1)(2)(3) (4) (5) (6) (n…m) (m+1)(m+2) (m+3) (m+4) + + (1) mount ID: unique identifier of the mount (may be reused after umount) + (2) parent ID: ID of parent (or of self for the top of the mount tree) + (3) major:minor: value of st_dev for files on filesystem + (4) root: root of the mount within the filesystem + (5) mount point: mount point relative to the process's root + (6) mount options: per mount options + (n…m) optional fields: zero or more fields of the form "tag[:value]" + (m+1) separator: marks the end of the optional fields + (m+2) filesystem type: name of filesystem of the form "type[.subtype]" + (m+3) mount source: filesystem specific information or "none" + (m+4) super options: per super block options Parsers should ignore all unrecognised optional fields. Currently the possible optional fields are: |