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Diffstat (limited to 'Documentation/filesystems/f2fs.rst')
| -rw-r--r-- | Documentation/filesystems/f2fs.rst | 82 |
1 files changed, 67 insertions, 15 deletions
diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst index ec8d99703ecb..b8ee761c9922 100644 --- a/Documentation/filesystems/f2fs.rst +++ b/Documentation/filesystems/f2fs.rst @@ -127,14 +127,14 @@ active_logs=%u Support configuring the number of active logs. In the current design, f2fs supports only 2, 4, and 6 logs. Default number is 6. disable_ext_identify Disable the extension list configured by mkfs, so f2fs - does not aware of cold files such as media files. + is not aware of cold files such as media files. inline_xattr Enable the inline xattrs feature. noinline_xattr Disable the inline xattrs feature. inline_xattr_size=%u Support configuring inline xattr size, it depends on flexible inline xattr feature. -inline_data Enable the inline data feature: New created small(<~3.4k) +inline_data Enable the inline data feature: Newly created small (<~3.4k) files can be written into inode block. -inline_dentry Enable the inline dir feature: data in new created +inline_dentry Enable the inline dir feature: data in newly created directory entries can be written into inode block. The space of inode block which is used to store inline dentries is limited to ~3.4k. @@ -203,9 +203,9 @@ usrjquota=<file> Appoint specified file and type during mount, so that quota grpjquota=<file> information can be properly updated during recovery flow, prjjquota=<file> <quota file>: must be in root directory; jqfmt=<quota type> <quota type>: [vfsold,vfsv0,vfsv1]. -offusrjquota Turn off user journelled quota. -offgrpjquota Turn off group journelled quota. -offprjjquota Turn off project journelled quota. +offusrjquota Turn off user journalled quota. +offgrpjquota Turn off group journalled quota. +offprjjquota Turn off project journalled quota. quota Enable plain user disk quota accounting. noquota Disable all plain disk quota option. whint_mode=%s Control which write hints are passed down to block @@ -266,6 +266,8 @@ inlinecrypt When possible, encrypt/decrypt the contents of encrypted inline encryption hardware. The on-disk format is unaffected. For more details, see Documentation/block/inline-encryption.rst. +atgc Enable age-threshold garbage collection, it provides high + effectiveness and efficiency on background GC. ======================== ============================================================ Debugfs Entries @@ -301,7 +303,7 @@ Usage # insmod f2fs.ko -3. Create a directory trying to mount:: +3. Create a directory to use when mounting:: # mkdir /mnt/f2fs @@ -315,7 +317,7 @@ mkfs.f2fs The mkfs.f2fs is for the use of formatting a partition as the f2fs filesystem, which builds a basic on-disk layout. -The options consist of: +The quick options consist of: =============== =========================================================== ``-l [label]`` Give a volume label, up to 512 unicode name. @@ -337,6 +339,8 @@ The options consist of: 1 is set by default, which conducts discard. =============== =========================================================== +Note: please refer to the manpage of mkfs.f2fs(8) to get full option list. + fsck.f2fs --------- The fsck.f2fs is a tool to check the consistency of an f2fs-formatted @@ -344,10 +348,12 @@ partition, which examines whether the filesystem metadata and user-made data are cross-referenced correctly or not. Note that, initial version of the tool does not fix any inconsistency. -The options consist of:: +The quick options consist of:: -d debug level [default:0] +Note: please refer to the manpage of fsck.f2fs(8) to get full option list. + dump.f2fs --------- The dump.f2fs shows the information of specific inode and dumps SSA and SIT to @@ -371,6 +377,37 @@ Examples:: # dump.f2fs -s 0~-1 /dev/sdx (SIT dump) # dump.f2fs -a 0~-1 /dev/sdx (SSA dump) +Note: please refer to the manpage of dump.f2fs(8) to get full option list. + +sload.f2fs +---------- +The sload.f2fs gives a way to insert files and directories in the exisiting disk +image. This tool is useful when building f2fs images given compiled files. + +Note: please refer to the manpage of sload.f2fs(8) to get full option list. + +resize.f2fs +----------- +The resize.f2fs lets a user resize the f2fs-formatted disk image, while preserving +all the files and directories stored in the image. + +Note: please refer to the manpage of resize.f2fs(8) to get full option list. + +defrag.f2fs +----------- +The defrag.f2fs can be used to defragment scattered written data as well as +filesystem metadata across the disk. This can improve the write speed by giving +more free consecutive space. + +Note: please refer to the manpage of defrag.f2fs(8) to get full option list. + +f2fs_io +------- +The f2fs_io is a simple tool to issue various filesystem APIs as well as +f2fs-specific ones, which is very useful for QA tests. + +Note: please refer to the manpage of f2fs_io(8) to get full option list. + Design ====== @@ -383,7 +420,7 @@ consists of a set of sections. By default, section and zone sizes are set to one segment size identically, but users can easily modify the sizes by mkfs. F2FS splits the entire volume into six areas, and all the areas except superblock -consists of multiple segments as described below:: +consist of multiple segments as described below:: align with the zone size <-| |-> align with the segment size @@ -486,7 +523,7 @@ one inode block (i.e., a file) covers:: `- direct node (1018) `- data (1018) -Note that, all the node blocks are mapped by NAT which means the location of +Note that all the node blocks are mapped by NAT which means the location of each node is translated by the NAT table. In the consideration of the wandering tree problem, F2FS is able to cut off the propagation of node updates caused by leaf data writes. @@ -566,7 +603,7 @@ When F2FS finds a file name in a directory, at first a hash value of the file name is calculated. Then, F2FS scans the hash table in level #0 to find the dentry consisting of the file name and its inode number. If not found, F2FS scans the next hash table in level #1. In this way, F2FS scans hash tables in -each levels incrementally from 1 to N. In each levels F2FS needs to scan only +each levels incrementally from 1 to N. In each level F2FS needs to scan only one bucket determined by the following equation, which shows O(log(# of files)) complexity:: @@ -707,7 +744,7 @@ WRITE_LIFE_LONG " WRITE_LIFE_LONG Fallocate(2) Policy ------------------- -The default policy follows the below posix rule. +The default policy follows the below POSIX rule. Allocating disk space The default operation (i.e., mode is zero) of fallocate() allocates @@ -720,7 +757,7 @@ Allocating disk space as a method of optimally implementing that function. However, once F2FS receives ioctl(fd, F2FS_IOC_SET_PIN_FILE) in prior to -fallocate(fd, DEFAULT_MODE), it allocates on-disk blocks addressess having +fallocate(fd, DEFAULT_MODE), it allocates on-disk block addressess having zero or random data, which is useful to the below scenario where: 1. create(fd) @@ -739,7 +776,7 @@ Compression implementation cluster can be compressed or not. - In cluster metadata layout, one special block address is used to indicate - cluster is compressed one or normal one, for compressed cluster, following + a cluster is a compressed one or normal one; for compressed cluster, following metadata maps cluster to [1, 4 << n - 1] physical blocks, in where f2fs stores data including compress header and compressed data. @@ -772,3 +809,18 @@ Compress metadata layout:: +-------------+-------------+----------+----------------------------+ | data length | data chksum | reserved | compressed data | +-------------+-------------+----------+----------------------------+ + +NVMe Zoned Namespace devices +---------------------------- + +- ZNS defines a per-zone capacity which can be equal or less than the + zone-size. Zone-capacity is the number of usable blocks in the zone. + F2FS checks if zone-capacity is less than zone-size, if it is, then any + segment which starts after the zone-capacity is marked as not-free in + the free segment bitmap at initial mount time. These segments are marked + as permanently used so they are not allocated for writes and + consequently are not needed to be garbage collected. In case the + zone-capacity is not aligned to default segment size(2MB), then a segment + can start before the zone-capacity and span across zone-capacity boundary. + Such spanning segments are also considered as usable segments. All blocks + past the zone-capacity are considered unusable in these segments. |