In practice, it is **extremely** rare for users to try to use more
than the first backup superblock located at the beginning of block
group #1. (i.e., at block number 32768 for file systems with a 4k
block size). This new compat feature restricts the backup superblock
to block group #1 and the last block group in the file system.
Aside from reducing the overhead of the file system by a small number
of blocks, by eliminating the rest of the backup superblocks, it
allows us to have a much more flexible metadata layout. For example,
we can force all of the allocation bitmaps and inode table blocks to
the beginning of the disk, which allows most of the disk to be
exclusively used for contiguous data blocks.
This simplifies taking advantage of certain HDD specific features,
such as Shingled Magnetic Recording (aka Shingled Drives), and the
TCG's OPAL Storage Specification where having a simple mapping between
LBA block ranges and the data blocks used by the file system can make
life much simpler.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Add a LOG2_CHECK mode for check_super_value() so that it is easy
to verify values that are supposed to be power-of-two values
(s_desc_size and s_inode_size so far). In ext2fs_check_desc()
also check for a power-of-two s_desc_size.
Print out s_desc_size in debugfs "stats" and dumpe2fs output, if
it is non-zero.
It turns out that the s_desc_size validation in check_super_block()
is not currently used by e2fsck, because the group descriptors are
verified earlier by ext2fs_check_desc(), and even without an
explicit check of s_desc_size the group descriptors fail to align
correctly on disk. It makes sense to keep the check_super_block()
regardless, in case the code changes at some point in the future.
Signed-off-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Record the type of checksum algorithm we're using for metadata in the
superblock, in case we ever want/need to change the algorithm.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Multi-mount protection is feature that allows mke2fs, e2fsck, and
others to detect if the filesystem is mounted on a remote node (on
SAN disks) and avoid corrupting the filesystem. For e2fsprogs this
means that it checks the MMP block to see if the filesystem is in use,
and marks the filesystem busy while e2fsck is running on the system.
This is useful on SAN disks that are shared between high-availability
servers, or accessible by multiple nodes that aren't in HA pairs. MMP
isn't intended to serve as a primary HA exclusion mechanism, but as a
failsafe to protect against user, software, or hardware errors.
There is no requirement that e2fsck updates the MMP block at regular
intervals, but e2fsck does this occasionally to provide useful
information to the sysadmin in case of a detected conflict.
For the kernel (since Linux 3.0) MMP adds a "heartbeat" mechanism to
periodically write to disk (every few seconds by default) to notify
other nodes that the filesystem is still in use and unsafe to modify.
Originally-by: Kalpak Shah <kalpak@clusterfs.com>
Signed-off-by: Johann Lombardi <johann@whamcloud.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
The DEFS line in MCONFIG had gotten so long that it exceeded 4k, and
this was starting to cause some tools heartburn. It also made "make
V=1" almost useless, since trying to following the individual commands
run by make was lost in the noise of all of the defines.
So fix this by putting the configure-generated defines in lib/config.h
and the directory pathnames to lib/dirpaths.h.
In addition, clean up some vestigal defines in configure.in and in the
Makefiles to further shorten the cc command lines.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reserve EXT4_FEATURE_RO_COMPAT_METADATA_CSUM and
EXT2_FEATURE_COMPAT_EXCLUDE_BITMAP. Also reserve fields in the
superblock and the inode for the checksums. In the block group
descriptor, reserve the exclude bitmap field for the snapshot feature,
and checksums for the inode and block allocation bitmaps.
With this commit, the metadata checksum and exclude bitmap features
should have reserved all of the fields they need in ext4's on-disk
format.
This commit also fixes an a missing byte swap for s_overhead_blocks.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Darrick J. Wong <djwong@us.ibm.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Fix several types of compiler warnings (unused variables/labels),
uninitialized variables, etc that are hit with gcc -Wall.
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
It turns out that it's very hard to calculate overheads in the face of
clustered allocation (bigalloc). This is because multiple metadata
blocks from different block groups can end up in the same allocation
cluster. Calculating the exact overhead requires O(all block bitmaps)
in memory, or O(number of block groups**2) in time. So we will
calculate this at mkfs time and stash it in the superblock.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This adds the superblock fields needed so that dumpe2fs works and the
code points and renames the superblock fields from describing
fragments to clusters.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This patch adds support for detecting the new 'quota' feature in ext4.
The patch reserves code points for usr and group quota inodes and also
for the feature flag EXT4_FEATURE_RO_COMPAT_QUOTA.
Signed-off-by: Aditya Kali <adityakali@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Add superblock fields which track where and when the first and most
recent file system errors occured. These fields are displayed by
dumpe2fs and cleared by e2fsck.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
We also support for byte-swapping the Next3 fields, although the
current Next3 implementation doesn't support big-endian systems.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
The top-level COPYING file states that the e2p and ext2fs libraries
are available under the LGPLv2. The files were incorrectly labelled.
Alex Thomas/Luster has been consulted wrt to the ext3_extents.h file;
the rest of the files were primarily authored by Theodore Ts'o.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This field tracks the lifetime amount of writes to the filesystem. It
will be updated by the kernel as well as by e2fsprogs programs which
write to the filesystem.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Make dumpe2fs and debugfs print out the s_min_extra_isize and
s_wanted_extra_isize fields from the superblock.
Update tests expect files as appropriate.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
The test_fs flag is an "ok to be used with test kernel code" flag. It
makes it easier for us to determine whether a filesystem should be
mounted using ext4 or not.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
The e2fsprogs and kernel implementation of directory hash tree has a
bug which causes the implementation to be dependent on whether
characters are signed or unsigned. Platforms such as the PowerPC,
Arm, and S/390 have signed characters by default, which means that
hash directories on those systems are incompatible with hash
directories on other systems, such as the x86.
To fix this we add a new flags field to the superblock, and define two
new bits in that field to indicate whether or not the directory should
be signed or unsigned. If the bits are not set, e2fsck and fixed
kernels will set them to the signed/unsigned value of the currently
running platform, and then respect those bits when calculating the
directory hash. This allows compatibility with current filesystems,
as well as allowing cross-architectural compatibility.
Addresses Debian Bug: #389772
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
superblock. E2fsck will automatically save the journal information
in the superblock if it is not there already, and will use it if the
journal inode appears to be corrupted. ext2fs_add_journal_inode()
will also save the backup information, so that new filesystems
created by mke2fs and filesystems that have journals added via
tune2fs will also have journal location written to the superblock as
well. Debugfs's logdump command has been enhanced so that it can
use the journal information in the superblock.
The debugfs man page has been improved to more fully describe the
logdump command.
Added two new functions, ext2fs_file_open2() and
ext2fs_inode_io_intern2() which take a pointer to an inode structure;
this is needed so that e2fsck and debugfs can synthesize a
fake journal inode and use it to access the journal.
the filesystem was created. It is set via mke2fs, and printed
via list_super2() (which is called by dumpe2fs).
Also, list_super2() will now print "n/a" if the last mount time
(s_mtime) is zero.
superblock. Dumpe2fs can now print out these fields, and they
can be modified using debugfs's set_super_value command. Also added
to debugfs was the ability to set s_uuid and s_journal_uuid features
as well.
ls.c (print_features): Added missing space when printing (none) as the
filesystem feature.
(list_super2): If the filesystem revision is unknown, say so.
ls.c (list_super): Use better description of s_last_orphan
.del-ext2_fs.h~7a460879, ChangeLog:
ext2_fs.h: Add comment explaining when journal fields are valid.
fsck.c (execute, wait_one): Treat fsck.ext3 the same as fsck.ext2
(because they are the same) for the purposes of the progress bar
display logic.
ChangeLog, ls.c:
ls.c (list_super): Display the journal information fields in the
superblock if the filesystem has a journal.
problem.c, problem.h (PR_0_HURD_CLEAR_FILETYPE): Add new problem code.
super.c (check_super_block): If the OS type in the superblock is the
Hurd, check to see if the filetype feature is set, and offer to clear
it if so. This needs to be done since the Hurd doesn't properly
support the filetype feature. (And since the hurd allows the
transmogrification of files to special files and vice versa --- for no
good reason that I can understand --- it can't support the filetype
feature for the forseeable future, either.)
ChangeLog, mke2fs.c:
mke2fs.c (main): We forcibly turn off the filetype feature if the OS
is the hurd, since the hurd doesn't support it. (And since the hurd
allows the transmogrification of files to special files and vice versa
--- for no good reason that I can understand --- it can't support the
filetype feature for the forseeable future, either.)
mke2fs.c (proceed_question): Fix reversed sense of proceed_question
that was busted due to the internationalization patch. Fixed bug
where if proceed_question was called twice, the input buffer wasn't
cleared of the previous question's newline.
ChangeLog, expect.1, expect.2, image.gz, name:
f_hurd: Add test for Hurd-specific features (right now, just checks to
make sure the filetype feature is cleared)
ChangeLog, ls.c:
ls.c (list_super): Change the string displayed for the Hurd to be
GNU/Hurd, instead of just "GNU".
Makefile.in, feature.c, e2p.h: New file which is used for displaying
and editing superblock feature sets.
ls.c (print_features, list_super): Add new function print_features
which is used to display the feature bits in the superblock.