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Diffstat (limited to 'Documentation/admin-guide/ext4.rst')
| -rw-r--r-- | Documentation/admin-guide/ext4.rst | 54 |
1 files changed, 33 insertions, 21 deletions
diff --git a/Documentation/admin-guide/ext4.rst b/Documentation/admin-guide/ext4.rst index 059ddcbe769d..5740d85439ff 100644 --- a/Documentation/admin-guide/ext4.rst +++ b/Documentation/admin-guide/ext4.rst @@ -92,6 +92,8 @@ Currently Available * efficient new ordered mode in JBD2 and ext4 (avoid using buffer head to force the ordering) * Case-insensitive file name lookups +* file-based encryption support (fscrypt) +* file-based verity support (fsverity) [1] Filesystems with a block size of 1k may see a limit imposed by the directory hash tree having a maximum depth of two. @@ -181,14 +183,17 @@ When mounting an ext4 filesystem, the following option are accepted: system after its metadata has been committed to the journal. commit=nrsec (*) - Ext4 can be told to sync all its data and metadata every 'nrsec' - seconds. The default value is 5 seconds. This means that if you lose - your power, you will lose as much as the latest 5 seconds of work (your - filesystem will not be damaged though, thanks to the journaling). This - default value (or any low value) will hurt performance, but it's good - for data-safety. Setting it to 0 will have the same effect as leaving - it at the default (5 seconds). Setting it to very large values will - improve performance. + This setting limits the maximum age of the running transaction to + 'nrsec' seconds. The default value is 5 seconds. This means that if + you lose your power, you will lose as much as the latest 5 seconds of + metadata changes (your filesystem will not be damaged though, thanks + to the journaling). This default value (or any low value) will hurt + performance, but it's good for data-safety. Setting it to 0 will have + the same effect as leaving it at the default (5 seconds). Setting it + to very large values will improve performance. Note that due to + delayed allocation even older data can be lost on power failure since + writeback of those data begins only after time set in + /proc/sys/vm/dirty_expire_centisecs. barrier=<0|1(*)>, barrier(*), nobarrier This enables/disables the use of write barriers in the jbd code. @@ -387,9 +392,16 @@ When mounting an ext4 filesystem, the following option are accepted: dax Use direct access (no page cache). See - Documentation/filesystems/dax.txt. Note that this option is + Documentation/filesystems/dax.rst. Note that this option is incompatible with data=journal. + inlinecrypt + When possible, encrypt/decrypt the contents of encrypted files using the + blk-crypto framework rather than filesystem-layer encryption. This + allows the use of inline encryption hardware. The on-disk format is + unaffected. For more details, see + Documentation/block/inline-encryption.rst. + Data Mode ========= There are 3 different data modes: @@ -517,21 +529,21 @@ Files in /sys/fs/ext4/<devname>: Ioctls ====== -There is some Ext4 specific functionality which can be accessed by applications -through the system call interfaces. The list of all Ext4 specific ioctls are -shown in the table below. +Ext4 implements various ioctls which can be used by applications to access +ext4-specific functionality. An incomplete list of these ioctls is shown in the +table below. This list includes truly ext4-specific ioctls (``EXT4_IOC_*``) as +well as ioctls that may have been ext4-specific originally but are now supported +by some other filesystem(s) too (``FS_IOC_*``). -Table of Ext4 specific ioctls +Table of Ext4 ioctls - EXT4_IOC_GETFLAGS + FS_IOC_GETFLAGS Get additional attributes associated with inode. The ioctl argument is - an integer bitfield, with bit values described in ext4.h. This ioctl is - an alias for FS_IOC_GETFLAGS. + an integer bitfield, with bit values described in ext4.h. - EXT4_IOC_SETFLAGS + FS_IOC_SETFLAGS Set additional attributes associated with inode. The ioctl argument is - an integer bitfield, with bit values described in ext4.h. This ioctl is - an alias for FS_IOC_SETFLAGS. + an integer bitfield, with bit values described in ext4.h. EXT4_IOC_GETVERSION, EXT4_IOC_GETVERSION_OLD Get the inode i_generation number stored for each inode. The @@ -606,7 +618,7 @@ kernel source: <file:fs/ext4/> programs: http://e2fsprogs.sourceforge.net/ -useful links: http://fedoraproject.org/wiki/ext3-devel +useful links: https://fedoraproject.org/wiki/ext3-devel http://www.bullopensource.org/ext4/ http://ext4.wiki.kernel.org/index.php/Main_Page - http://fedoraproject.org/wiki/Features/Ext4 + https://fedoraproject.org/wiki/Features/Ext4 |