Refactor code to print journal superblock information

[tools/e2fsprogs.git] / debugfs / debugfs.8.in

diff --git a/debugfs/debugfs.8.in b/debugfs/debugfs.8.in
index ab6adc4..87d487e 100644 (file)
--- a/debugfs/debugfs.8.in
+++ b/debugfs/debugfs.8.in
@@ -31,6 +31,10 @@ request
 data_source_device
 ]
 [
+.B \-z
+.I undo_file
+]
+[
 device
 ]
 .SH DESCRIPTION
@@ -38,10 +42,9 @@ The
 .B debugfs
 program is an interactive file system debugger. It can be used to
 examine and change the state of an ext2, ext3, or ext4 file system.
-.br
+.PP
 .I device
-is the special file corresponding to the device containing the
-file system (e.g /dev/hdXX).
+is a block device (e.g., /dev/sdXX) or a file containing the file system.
 .SH OPTIONS
 .TP
 .I \-w
@@ -91,8 +94,10 @@ should be used when reading blocks not found in the ext2 image file.
 This includes data, directory, and indirect blocks.
 .TP
 .I -b blocksize
-Forces the use of the given block size for the file system, rather than
-detecting the correct block size as normal.
+Forces the use of the given block size (in bytes) for the file system,
+rather than detecting the correct block size automatically.  (This
+option is rarely needed; it is used primarily when the file system is
+extremely badly damaged/corrupted.)
 .TP
 .I -s superblock
 Causes the file system superblock to be read from the given block
@@ -101,7 +106,9 @@ number, instead of using the primary superblock (located at an offset of
 .I -s
 option, you must also provide the blocksize of the filesystem via the
 .I -b
-option.
+option.   (This
+option is rarely needed; it is used primarily when the file system is
+extremely badly damaged/corrupted.)
 .TP
 .I -f cmd_file
 Causes
@@ -130,6 +137,16 @@ and then exit.
 print the version number of
 .B debugfs
 and exit.
+.TP
+.BI \-z " undo_file"
+Before overwriting a file system block, write the old contents of the block to
+an undo file.  This undo file can be used with e2undo(8) to restore the old
+contents of the file system should something go wrong.  If the empty string is
+passed as the undo_file argument, the undo file will be written to a file named
+resize2fs-\fIdevice\fR.e2undo in the directory specified via the
+\fIE2FSPROGS_UNDO_DIR\fR environment variable.
+
+WARNING: The undo file cannot be used to recover from a power or system crash.
 .SH SPECIFYING FILES
 Many
 .B debugfs
@@ -162,7 +179,7 @@ This is a list of the commands which
 .B debugfs
 supports.
 .TP
-.BI blocks " filespace"
+.BI blocks " filespec"
 Print the blocks used by the inode
 .I filespec
 to stdout.
@@ -208,6 +225,12 @@ master superblock.
 Clear the contents of the inode
 .IR filespec .
 .TP
+.BI copy_inode " source_inode destination_inode"
+Copy the conents of the inode structure in
+.I source_inode
+and use it to overwrite the inode structure at
+.IR destination_inode .
+.TP
 .BI dirsearch " filespec filename"
 Search the directory
 .I filespec
@@ -229,8 +252,13 @@ option is given set the owner, group and permissions information on
 to match
 .IR filespec .
 .TP
-.B dump_mmp
-Display the multiple-mount protection (mmp) field values.
+.BI dump_mmp " [mmp_block]"
+Display the multiple-mount protection (mmp) field values.  If
+.I mmp_block
+is specified then verify and dump the MMP values from the given block
+number, otherwise use the
+.B s_mmp_block
+field in the superblock to locate and use the existing MMP block.
 .TP
 .BI dx_hash " [-h hash_alg] [-s hash_seed] filename"
 Calculate the directory hash of
@@ -292,6 +320,13 @@ from the file \fIfilespec\fR.
 Expand the directory
 .IR filespec .
 .TP
+.BI fallocate " filespec start_block [end_block]
+Allocate and map uninitialized blocks into \fIfilespec\fR between
+logical block \fIstart_block\fR and \fIend_block\fR, inclusive.  If
+\fIend_block\fR is not supplied, this function maps until it runs out
+of free disk blocks or the maximum file size is reached.  Existing
+mappings are left alone.
+.TP
 .BI feature " [fs_feature] [-fs_feature] ..."
 Set or clear various filesystem features in the superblock.  After setting
 or clearing any filesystem features that were requested, print the current
@@ -535,7 +570,7 @@ to those inodes.  The
 flag will enable checking the file type information in the directory
 entry to make sure it matches the inode's type.
 .TP
-.BI open " [-weficD] [-b blocksize] [-s superblock] device"
+.BI open " [-weficD] [-b blocksize] [-s superblock] [-z undo_file] device"
 Open a filesystem for editing.  The
 .I -f
 flag forces the filesystem to be opened even if there are some unknown