.SH DESCRIPTION
.B e2fsck
is used to check the ext2/ext3/ext4 family of file systems.
-For ext3 and ext4 filesystems that use a journal, if the system has been
+For ext3 and ext4 file systems that use a journal, if the system has been
shut down uncleanly without any errors, normally, after replaying the
committed transactions in the journal, the file system should be
-marked as clean. Hence, for filesystems that use journalling,
+marked as clean. Hence, for file systems that use journaling,
.B e2fsck
will normally replay the journal and exit, unless its superblock
indicates that further checking is required.
.PP
Note that in general it is not safe to run
.B e2fsck
-on mounted filesystems. The only exception is if the
+on mounted file systems. The only exception is if the
.B \-n
option is specified, and
.BR \-c ,
.I not
specified. However, even if it is safe to do so, the results printed by
.B e2fsck
-are not valid if the filesystem is mounted. If
+are not valid if the file system is mounted. If
.B e2fsck
-asks whether or not you should check a filesystem which is mounted,
+asks whether or not you should check a file system which is mounted,
the only correct answer is ``no''. Only experts who really know what
they are doing should consider answering this question in any other way.
.PP
or
.BR \-p
are specified), the program will ask the user to fix each problem found in the
-filesystem. A response of 'y' will fix the error; 'n' will leave the error
+file system. A response of 'y' will fix the error; 'n' will leave the error
unfixed; and 'a' will fix the problem and all subsequent problems; pressing
Enter will proceed with the default response, which is printed before the
question mark. Pressing Control-C terminates e2fsck immediately.
specified by
.IR superblock .
This option is normally used when the primary superblock has been
-corrupted. The location of the backup superblock is dependent on the
-filesystem's blocksize. For filesystems with 1k blocksizes, a backup
-superblock can be found at block 8193; for filesystems with 2k
-blocksizes, at block 16384; and for 4k blocksizes, at block 32768.
+corrupted. The location of backup superblocks is dependent on the
+file system's blocksize, the number of blocks per group, and features
+such as
+.BR sparse_super .
.IP
Additional backup superblocks can be determined by using the
.B mke2fs
program using the
.B \-n
-option to print out where the superblocks were created. The
-.B \-b
-option to
-.BR mke2fs ,
-which specifies blocksize of the filesystem must be specified in order
-for the superblock locations that are printed out to be accurate.
+option to print out where the superblocks exist, supposing
+.B mke2fs
+is supplied with arguments that are consistent with the file system's layout
+(e.g. blocksize, blocks per group,
+.BR sparse_super ,
+etc.).
.IP
If an alternative superblock is specified and
-the filesystem is not opened read-only, e2fsck will make sure that the
+the file system is not opened read-only, e2fsck will make sure that the
primary superblock is updated appropriately upon completion of the
-filesystem check.
+file system check.
.TP
.BI \-B " blocksize"
Normally,
This option causes
.B e2fsck
to write completion information to the specified file descriptor
-so that the progress of the filesystem
+so that the progress of the file system
check can be monitored. This option is typically used by programs
which are running
.BR e2fsck .
.BR e2fsck ).
.TP
.B \-D
-Optimize directories in filesystem. This option causes e2fsck to
-try to optimize all directories, either by reindexing them if the
-filesystem supports directory indexing, or by sorting and compressing
-directories for smaller directories, or for filesystems using
+Optimize directories in file system. This option causes e2fsck to
+try to optimize all directories, either by re-indexing them if the
+file system supports directory indexing, or by sorting and compressing
+directories for smaller directories, or for file systems using
traditional linear directories.
.IP
Even without the
benefit from being indexed, or if the index structures are corrupted
and need to be rebuilt. The
.B \-D
-option forces all directories in the filesystem to be optimized. This can
+option forces all directories in the file system to be optimized. This can
sometimes make them a little smaller and slightly faster to search, but
in practice, you should rarely need to use this option.
.IP
.BI ea_ver= extended_attribute_version
Set the version of the extended attribute blocks which
.B e2fsck
-will require while checking the filesystem. The version number may
+will require while checking the file system. The version number may
be 1 or 2. The default extended attribute version format is 2.
.TP
.BI journal_only
.TP
.BI fragcheck
During pass 1, print a detailed report of any discontiguous blocks for
-files in the filesystem.
+files in the file system.
.TP
.BI discard
Attempt to discard free blocks and unused inode blocks after the full
-filesystem check (discarding blocks is useful on solid state devices and sparse
+file system check (discarding blocks is useful on solid state devices and sparse
/ thin-provisioned storage). Note that discard is done in pass 5 AFTER the
-filesystem has been fully checked and only if it does not contain recognizable
+file system has been fully checked and only if it does not contain recognizable
errors. However there might be cases where
.B e2fsck
does not fully recognize a problem and hence in this case this
.TP
.BI no_optimize_extents
Do not offer to optimize the extent tree by eliminating unnecessary
-width or depth.
+width or depth. This can also be enabled in the options section of
+.BR /etc/e2fsck.conf .
+.TP
+.BI optimize_extents
+Offer to optimize the extent tree by eliminating unnecessary
+width or depth. This is the default unless otherwise specified in
+.BR /etc/e2fsck.conf .
+.TP
+.BI inode_count_fullmap
+Trade off using memory for speed when checking a file system with a
+large number of hard-linked files. The amount of memory required is
+proportional to the number of inodes in the file system. For large file
+systems, this can be gigabytes of memory. (For example, a 40TB file system
+with 2.8 billion inodes will consume an additional 5.7 GB memory if this
+optimization is enabled.) This optimization can also be enabled in the
+options section of
+.BR /etc/e2fsck.conf .
+.TP
+.BI no_inode_count_fullmap
+Disable the
+.B inode_count_fullmap
+optimization. This is the default unless otherwise specified in
+.BR /etc/e2fsck.conf .
.TP
.BI readahead_kb
Use this many KiB of memory to pre-fetch metadata in the hopes of reducing
e2fsck runtime. By default, this is set to the size of two block groups' inode
-tables (typically 4MiB on a regular ext4 filesystem); if this amount is more
+tables (typically 4MiB on a regular ext4 file system); if this amount is more
than 1/50th of total physical memory, readahead is disabled. Set this to zero
to disable readahead entirely.
.TP
Only fix damaged metadata; do not optimize htree directories or compress
extent trees. This option is incompatible with the -D and -E bmap2extent
options.
+.TP
+.BI check_encoding
+Force verification of encoded filenames in case-insensitive directories.
+This is the default mode if the file system has the strict flag enabled.
+.TP
+.BI unshare_blocks
+If the file system has shared blocks, with the shared blocks read-only feature
+enabled, then this will unshare all shared blocks and unset the read-only
+feature bit. If there is not enough free space then the operation will fail.
+If the file system does not have the read-only feature bit, but has shared
+blocks anyway, then this option will have no effect. Note when using this
+option, if there is no free space to clone blocks, there is no prompt to
+delete files and instead the operation will fail.
+.IP
+Note that unshare_blocks implies the "-f" option to ensure that all passes
+are run. Additionally, if "-n" is also specified, e2fsck will simulate trying
+to allocate enough space to deduplicate. If this fails, the exit code will
+be non-zero.
.RE
.TP
.B \-f
Force checking even if the file system seems clean.
.TP
.B \-F
-Flush the filesystem device's buffer caches before beginning. Only
+Flush the file system device's buffer caches before beginning. Only
really useful for doing
.B e2fsck
time trials.
@JDEV@.TP
@JDEV@.BI \-j " external-journal"
-@JDEV@Set the pathname where the external-journal for this filesystem can be
+@JDEV@Set the pathname where the external-journal for this file system can be
@JDEV@found.
.TP
.BI \-k
one generated by the
.BR badblocks (8)
program. Note that the block numbers are based on the blocksize
-of the filesystem. Hence,
+of the file system. Hence,
.BR badblocks (8)
-must be given the blocksize of the filesystem in order to obtain correct
+must be given the blocksize of the file system in order to obtain correct
results. As a result, it is much simpler and safer to use the
.B -c
option to
in the file are added to the bad blocks list.)
.TP
.B \-n
-Open the filesystem read-only, and assume an answer of `no' to all
+Open the file system read-only, and assume an answer of `no' to all
questions. Allows
.B e2fsck
to be used non-interactively. This option
Automatically repair ("preen") the file system. This option will cause
.B e2fsck
to automatically
-fix any filesystem problems that can be safely fixed without human
+fix any file system problems that can be safely fixed without human
intervention. If
.B e2fsck
discovers a problem which may require the system administrator
to stop displaying a completion bar or emitting progress information.
.SH REPORTING BUGS
Almost any piece of software will have bugs. If you manage to find a
-filesystem which causes
+file system which causes
.B e2fsck
to crash, or which
.B e2fsck
.B C
so that the transcript of e2fsck's output will be useful to me.)
If you
-have a writable filesystem where the transcript can be stored, the
+have a writable file system where the transcript can be stored, the
.BR script (1)
program is a handy way to save the output of
.B e2fsck
which can sent to me after being first run through
.BR uuencode (1).
The most useful data you can send to help reproduce
-the bug is a compressed raw image dump of the filesystem, generated using
+the bug is a compressed raw image dump of the file system, generated using
.BR e2image (8).
See the
.BR e2image (8)
Always include the full version string which
.B e2fsck
displays when it is run, so I know which version you are running.
+.SH ENVIRONMENT
+.TP
+.BI E2FSCK_CONFIG
+Determines the location of the configuration file (see
+.BR e2fsck.conf (5)).
.SH AUTHOR
This version of
.B e2fsck