Documentation/admin-guide/ext4.rst

7 Ext4 is an advanced level of the ext3 filesystem which incorporates
35   - Create a new filesystem using the ext4 filesystem type:
39     Or to configure an existing ext3 filesystem to support extents:
43     If the filesystem was created with 128 byte inodes, it can be
66     the filesystem with a large journal can also be helpful for
106 case-sensitive directories in the same filesystem.  It is enabled by
110 case-insensitive directories, the filesystem must have the
111 casefold feature, which stores the filesystem-wide encoding
132 filesystem, which select its preferred behavior by enabling/disabling
134 filesystem did not require strict mode, it falls back to considering the
141 When mounting an ext4 filesystem, the following option are accepted:
145         Mount filesystem read only. Note that ext4 will replay the journal (and
147         options "ro,noload" can be used to prevent writes to the filesystem.
167         Don't load the journal on mounting.  Note that if the filesystem was
169         filesystem containing inconsistencies that can lead to any number of
189         metadata changes (your filesystem will not be damaged though, thanks
226         This is normally used while remounting a filesystem which is already
230         Remount the filesystem read-only on an error.
233         Keep going on a filesystem error.
262         These options are ignored by the filesystem. They are used only by
268         These options tell filesystem details about quota so that quota
274         Number of filesystem blocks that mballoc will try to use for allocation
290         Maximum amount of time ext4 should wait for additional filesystem
355         filesystem metadata blocks within internal data structures.  This
358         overlap with filesystem metadata blocks.
389         blk-crypto framework rather than filesystem-layer encryption. This
429 /proc/fs/ext4.  Each mounted filesystem will have a directory in
443 /sys/fs/ext4.  Each mounted filesystem will have a directory in
454         the page cache, but which do not have their location in the filesystem
470         have been written to this filesystem since it was created.
507         have been written to this filesystem since it was mounted.
525 by some other filesystem(s) too (``FS_IOC_*``).
549         to resize filesystem to the end of the last existing block group,
552         the filesystem new block count.
567         allows online resize of the filesystem to the end of the last existing
572         This ioctl operates on the filesystem itself.  It converts (migrates)
577         ext4 filesystem, however suggestion is to create fresh ext4 filesystem
578         and copy data from the backup. Note, that filesystem has to support
589         Resize the filesystem to a new size.  The number of blocks of resized
590         filesystem is passed in via 64 bit integer argument.  The kernel
598         the filesystem, where it can't be changed by a normal user by accident.