4.t

早期freebsd实现

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.ds RH Appendix A \- Fsck Error Conditions
.NH
Appendix A \- Fsck Error Conditions
.NH 2 
Conventions
.PP
.I Fsck
is
a multi-pass file system check program.
Each file system pass invokes a different Phase of the
.I fsck
program.
After the initial setup,
.I fsck
performs successive Phases over each file system,
checking blocks and sizes,
path-names,
connectivity,
reference counts,
and the map of free blocks,
(possibly rebuilding it),
and performs some cleanup.
.LP
Normally
.I fsck
is run non-interactively to
.I preen
the file systems after an unclean halt.
While preen'ing a file system,
it will only fix corruptions that are expected
to occur from an unclean halt.
These actions are a proper subset of the actions that 
.I fsck
will take when it is running interactively.
Throughout this appendix many errors have several options
that the operator can take.
When an inconsistency is detected,
.I fsck
reports the error condition to the operator.
If a response is required,
.I fsck
prints a prompt message and
waits for a response.
When preen'ing most errors are fatal.
For those that are expected,
the response taken is noted.
This appendix explains the meaning of each error condition,
the possible responses, and the related error conditions.
.LP
The error conditions are organized by the
.I Phase
of the
.I fsck
program in which they can occur.
The error conditions that may occur
in more than one Phase
will be discussed in initialization.
.NH 2 
Initialization
.PP
Before a file system check can be performed, certain
tables have to be set up and certain files opened.
This section concerns itself with the opening of files and
the initialization of tables.
This section lists error conditions resulting from
command line options,
memory requests,
opening of files,
status of files,
file system size checks,
and creation of the scratch file.
All the initialization errors are fatal
when the file system is being preen'ed.
.sp
.LP
.B "\fIC\fP option?"
.br
\fIC\fP is not a legal option to
.I fsck ;
legal options are \-b, \-c, \-y, \-n, and \-p.
.I Fsck
terminates on this error condition.
See the
.I fsck (8)
manual entry for further detail.
.sp
.LP
.B "cannot alloc NNN bytes for blockmap"
.br
.B "cannot alloc NNN bytes for freemap"
.br
.B "cannot alloc NNN bytes for statemap"
.br
.B "cannot alloc NNN bytes for lncntp"
.br
.I Fsck 's
request for memory for its virtual
memory tables failed.
This should never happen.
.I Fsck
terminates on this error condition.
See a guru.
.sp
.LP
.B "Can't open checklist file: \fIF\fP"
.br
The file system checklist file
\fIF\fP (usually
.I /etc/fstab )
can not be opened for reading.
.I Fsck
terminates on this error condition.
Check access modes of \fIF\fP.
.sp
.LP
.B "Can't stat root"
.br
.I Fsck 's
request for statistics about the root directory ``/'' failed.
This should never happen.
.I Fsck
terminates on this error condition.
See a guru.
.sp
.LP
.B "Can't stat \fIF\fP"
.br
.B "Can't make sense out of name \fIF\fP"
.br
.I Fsck 's
request for statistics about the file system \fIF\fP failed.
When running manually,
it ignores this file system
and continues checking the next file system given.
Check access modes of \fIF\fP.
.sp
.LP
.B "Can't open \fIF\fP"
.br
.I Fsck 's
request attempt to open the file system \fIF\fP failed.
When running manually, it ignores this file system
and continues checking the next file system given.
Check access modes of \fIF\fP.
.sp
.LP
.B "\fIF\fP: (NO WRITE)"
.br
Either the \-n flag was specified or
.I fsck 's
attempt to open the file system \fIF\fP for writing failed.
When running manually,
all the diagnostics are printed out,
but no modifications are attempted to fix them.
.sp
.LP
.B "file is not a block or character device; OK"
.br
You have given
.I fsck
a regular file name by mistake.
Check the type of the file specified.
.LP
Possible responses to the OK prompt are:
.IP YES
ignore this error condition.
.IP NO
ignore this file system and continues checking
the next file system given.
.sp
.LP
.B "UNDEFINED OPTIMIZATION IN SUPERBLOCK (SET TO DEFAULT)"
.br
The superblock optimization parameter is neither OPT_TIME
nor OPT_SPACE.
.LP
Possible responses to the SET TO DEFAULT prompt are:
.IP YES
The superblock is set to request optimization to minimize
running time of the system.
(If optimization to minimize disk space utilization is
desired, it can be set using \fItunefs\fP(8).)
.IP NO
ignore this error condition.
.sp
.LP
.B "IMPOSSIBLE MINFREE=\fID\fP IN SUPERBLOCK (SET TO DEFAULT)"
.br
The superblock minimum space percentage is greater than 99%
or less then 0%.
.LP
Possible responses to the SET TO DEFAULT prompt are:
.IP YES
The minfree parameter is set to 10%.
(If some other percentage is desired,
it can be set using \fItunefs\fP(8).)
.IP NO
ignore this error condition.
.sp
.LP
.B "IMPOSSIBLE INTERLEAVE=\fID\fP IN SUPERBLOCK (SET TO DEFAULT)"
.br
The file system interleave is less than or equal to zero.
.LP
Possible responses to the SET TO DEFAULT prompt are:
.IP YES
The interleave parameter is set to 1.
.IP NO
ignore this error condition.
.sp
.LP
.B "IMPOSSIBLE NPSECT=\fID\fP IN SUPERBLOCK (SET TO DEFAULT)"
.br
The number of physical sectors per track is less than the number
of usable sectors per track.
.LP
Possible responses to the SET TO DEFAULT prompt are:
.IP YES
The npsect parameter is set to the number of usable sectors per track.
.IP NO
ignore this error condition.
.sp
.LP
One of the following messages will appear:
.br
.B "MAGIC NUMBER WRONG"
.br
.B "NCG OUT OF RANGE"
.br
.B "CPG OUT OF RANGE"
.br
.B "NCYL DOES NOT JIVE WITH NCG*CPG"
.br
.B "SIZE PREPOSTEROUSLY LARGE"
.br
.B "TRASHED VALUES IN SUPER BLOCK"
.br
and will be followed by the message:
.br
.B "\fIF\fP: BAD SUPER BLOCK: \fIB\fP"
.br
.B "USE -b OPTION TO FSCK TO SPECIFY LOCATION OF AN ALTERNATE"
.br
.B "SUPER-BLOCK TO SUPPLY NEEDED INFORMATION; SEE fsck(8)."
.br
The super block has been corrupted. 
An alternative super block must be selected from among those
listed by
.I newfs
(8) when the file system was created.
For file systems with a blocksize less than 32K,
specifying \-b 32 is a good first choice.
.sp
.LP
.B "INTERNAL INCONSISTENCY: \fIM\fP"
.br
.I Fsck 's
has had an internal panic, whose message is specified as \fIM\fP.
This should never happen.
See a guru.
.sp
.LP
.B "CAN NOT SEEK: BLK \fIB\fP (CONTINUE)"
.br
.I Fsck 's
request for moving to a specified block number \fIB\fP in
the file system failed.
This should never happen.
See a guru.
.LP
Possible responses to the CONTINUE prompt are:
.IP YES
attempt to continue to run the file system check.
Often,
however the problem will persist.
This error condition will not allow a complete check of the file system.
A second run of
.I fsck
should be made to re-check this file system.
If the block was part of the virtual memory buffer
cache,
.I fsck
will terminate with the message ``Fatal I/O error''.
.IP NO
terminate the program.
.sp
.LP
.B "CAN NOT READ: BLK \fIB\fP (CONTINUE)"
.br
.I Fsck 's
request for reading a specified block number \fIB\fP in
the file system failed.
This should never happen.
See a guru.
.LP
Possible responses to the CONTINUE prompt are:
.IP YES
attempt to continue to run the file system check.
It will retry the read and print out the message:
.br
.B "THE FOLLOWING SECTORS COULD NOT BE READ: \fIN\fP"
.br
where \fIN\fP indicates the sectors that could not be read.
If 
.I fsck
ever tries to write back one of the blocks on which the read failed
it will print the message:
.br
.B "WRITING ZERO'ED BLOCK \fIN\fP TO DISK"
.br
where \fIN\fP indicates the sector that was written with zero's.
If the disk is experiencing hardware problems, the problem will persist.
This error condition will not allow a complete check of the file system.
A second run of
.I fsck
should be made to re-check this file system.
If the block was part of the virtual memory buffer
cache,
.I fsck
will terminate with the message ``Fatal I/O error''.
.IP NO
terminate the program.
.sp
.LP
.B "CAN NOT WRITE: BLK \fIB\fP (CONTINUE)"
.br
.I Fsck 's
request for writing a specified block number \fIB\fP
in the file system failed.
The disk is write-protected;
check the write protect lock on the drive.
If that is not the problem, see a guru.
.LP
Possible responses to the CONTINUE prompt are:
.IP YES
attempt to continue to run the file system check.
The write operation will be retried with the failed blocks
indicated by the message:
.br
.B "THE FOLLOWING SECTORS COULD NOT BE WRITTEN: \fIN\fP"
.br
where \fIN\fP indicates the sectors that could not be written.
If the disk is experiencing hardware problems, the problem will persist.
This error condition will not allow a complete check of the file system.
A second run of
.I fsck
should be made to re-check this file system.
If the block was part of the virtual memory buffer
cache,
.I fsck
will terminate with the message ``Fatal I/O error''.
.IP NO
terminate the program.
.sp
.LP
.B "bad inode number DDD to ginode"
.br
An internal error has attempted to read non-existent inode \fIDDD\fP.
This error causes 
.I fsck
to exit.
See a guru.
.NH 2 
Phase 1 \- Check Blocks and Sizes
.PP
This phase concerns itself with
the inode list.
This section lists error conditions resulting from
checking inode types,
setting up the zero-link-count table,
examining inode block numbers for bad or duplicate blocks,
checking inode size,
and checking inode format.
All errors in this phase except
.B "INCORRECT BLOCK COUNT"
and
.B "PARTIALLY TRUNCATED INODE"
are fatal if the file system is being preen'ed.
.sp
.LP
.B "UNKNOWN FILE TYPE I=\fII\fP (CLEAR)"
.br
The mode word of the inode \fII\fP indicates that the inode is not a
special block inode, special character inode, socket inode, regular inode,
symbolic link, or directory inode.
.LP
Possible responses to the CLEAR prompt are:
.IP YES
de-allocate inode \fII\fP by zeroing its contents.
This will always invoke the UNALLOCATED error condition in Phase 2
for each directory entry pointing to this inode.
.IP NO
ignore this error condition.
.sp
.LP
.B "PARTIALLY TRUNCATED INODE I=\fII\fP (SALVAGE)"
.br
.I Fsck
has found inode \fII\fP whose size is shorter than the number of
blocks allocated to it.
This condition should only occur if the system crashes while in the
midst of truncating a file.
When preen'ing the file system, 
.I fsck
completes the truncation to the specified size.
.LP
Possible responses to SALVAGE are:
.IP YES
complete the truncation to the size specified in the inode.
.IP NO
ignore this error condition.
.sp
.LP
.B "LINK COUNT TABLE OVERFLOW (CONTINUE)"
.br
An internal table for
.I fsck
containing allocated inodes with a link count of
zero cannot allocate more memory.
Increase the virtual memory for
.I fsck .
.LP
Possible responses to the CONTINUE prompt are:
.IP YES
continue with the program.
This error condition will not allow a complete check of the file system.
A second run of
.I fsck
should be made to re-check this file system.
If another allocated inode with a zero link count is found,
this error condition is repeated.
.IP NO
terminate the program.
.sp
.LP
.B "\fIB\fP BAD I=\fII\fP"
.br
Inode \fII\fP contains block number \fIB\fP with a number
lower than the number of the first data block in the file system or
greater than the number of the last block
in the file system.
This error condition may invoke the