- VX_SETCACHE
Set caching advisories.
These advisories allow an application
to indicate to the file system
which forms of caching
would be most advantageous.
NOTE:
VX_SETCACHE
is available
with the VxFS Advanced package only.
The values for
arg
are such that
multiple advisories may be set
by combining values with bitwise
OR
operations.
The possible values for
arg
are
- VX_RANDOM
Indicates that the file
is being accessed randomly.
Read-ahead should not be performed.
- VX_SEQ
Indicates that the file
is being accessed sequentially.
Maximum read-ahead should be performed.
- VX_DIRECT
Indicates that data
associated with read and write operations
is to be transferred directly
to or from the user supplied buffer,
without being cached.
When this options is enabled,
all I/O operations must begin on block boundaries
and must be a multiple of the block size in length.
The buffer supplied with the I/O operations
must be aligned to a page boundary.
If an I/O request fails to meet alignment criteria,
or the file is currently being accessed for mapped I/O,
the I/O request will be performed
as a data synchronous I/O operation.
- VX_NOREUSE
Indicates that buffered data
does not need to be retained
in anticipation of further use
by the application.
- VX_DSYNC
Indicates that data synchronous I/O mode is desired.
In data synchronous I/O mode,
a write operation returns to the caller
after the data has been transferred to external media,
but the inode is not updated synchronously
if only the times in the inode need to be updated.
Only one of
VX_RANDOM,
VX_SEQ,
or
VX_DIRECT
may be specified.
The
VX_NOREUSE
and
VX_DSYNC
options may not be used in conjunction with
VX_DIRECT.
The caching advisories for a file
are maintained on a per-file basis.
Changes made to the advisories by a process
affect I/O operations by all processes
currently accessing the file.
The
VX_SETCACHE
ioctl returns a 0
if the caching advisories
are successfully set.
If the operation fails,
the return value is -1
and the external variable
errno
will be a general DIAGNOSTIC.
- VX_GETCACHE
Get caching advisories in effect for the file.
The argument
arg
should be a pointer to an
int.
The
VX_GETCACHE
ioctl returns a 0
if the caching advisories
are successfully obtained
and the advisories are returned in
arg.
If the operation fails,
the return value is -1
and the external variable
errno
will be a general DIAGNOSTIC.
- VX_SETEXT
Set extent information.
NOTE:
VX_SETEXT
is available
with the VxFS Advanced package only.
The extent information is set
according to the parameters specified by
arg.
The argument
arg
points to a structure of type
vx_ext
defined in
sys/fs/vx_ioctl.h,
which contains the following members:
off_t ext_size; /* extent size in fs blocks */
off_t reserve; /* space reservation in fs blocks */
int a_flags; /* allocation flags */
The
ext_size
element is used to request a fixed extent size,
in file system blocks,
for the file.
If a fixed extent size is not required,
zero should be used
to allow the default allocation policy to be used.
Changes to the fixed extent size
made after the file contains indirect blocks
have no effect unless all current indirect blocks
are freed via file truncation
and/or reservation deallocation.
The
reserve
element is used to set the amount of space,
in file system blocks,
preallocated to the file.
If the
reserve
amount is greater than the current reservation,
the allocation for the file is increased
to match the
reserve
amount.
If the
reserve
amount is less than the current reservation,
the allocation is decreased.
The allocation will not be reduced
to less than the current file size.
File reservation cannot be increased
beyond the
ulimit(2)
of the requesting process.
However,
an existing reservation will not be trimmed
to the requesting process's
ulimit(2).
Reservation of space for existing sparse files
will not cause blocks to be allocated
to fill in the holes,
but will only allocate blocks
after the end of the file.
Thus,
it's possible to have a larger reservation for a file
than blocks in the file.
The reservation amount is independent of file size
since reservation is used to preallocate space for a file.
The
a_flags
element is used to indicate
the type of reservation required.
The choices are:
- VX_NOEXTEND
The file may not be extended
once the current reservation is exceeded.
The reservation may be increased if necessary
by another invocation of the ioctl,
but the file will not be automatically extended.
- VX_TRIM
The reservation for the file
is to be trimmed to the current file size
upon last close by all processes that have the file open.
- VX_CONTIGUOUS
The reservation must be allocated contiguously
(as a single extent).
ext_size
will become the fixed extent size
for subsequent allocations,
but has no affect on this one.
The reservation will fail
if the file has gone into indirect extents,
unless the amount of space requested
is the same as the indirect extent size.
If the contiguous allocation request
is done on an empty file,
this will not happen.
- VX_ALIGN
Align all new extents on an
ext_size
boundary
relative to the starting block
of an allocation unit.
If
VX_CONTIGUOUS
is also set,
the single extent
allocated during this invocation
is not subject to the alignment restriction.
- VX_NORESERVE
The reservation is to be made
as a non-persistent allocation to the file.
The on-disk inode will not be updated
with the reservation information
so that the reservation
will not survive a system crash.
The reservation is associated with the file
until the close of the file.
The reservation is trimmed to the current file size
on close.
- VX_CHGSIZE
The reservation is to be immediately incorporated
into the file.
The file's on-disk inode is updated
with the size
increased to include the reserved space.
Unlike an
fcntl(2)
F_FREESP
operation which ``truncates up''
(see
fcntl(2)),
the space included in the file
is not initialized.
This operation is restricted
to users with appropriate privileges.
Write permission to a file
is required to set extent information,
but any process that can open the file
can get the extent information.
Extent information only applies to regular files.
Only one set of extent information is kept per file.
Only the
VX_ALIGN
and
VX_NOEXTEND
allocation flags
are persistent attributes of the file.
Other allocation flags may have persistent effects,
but are not visible as allocation flags.
VX_ALIGN,
VX_NOEXTEND,
and
VX_TRIM
are the only flags visible through the
VX_GETEXT
ioctl.
The
VX_SETEXT
ioctl returns a 0
if the extent information
is successfully set.
If the operation fails,
the return value is -1
and the external variable
errno
will be a general DIAGNOSTIC.
- VX_GETEXT
Get extent information.
Return the extent information associated with
fildes.
The argument
arg
points to a structure of type
vx_ext
as defined in
sys/fs/vx_ioctl.h.
Only persistent extent attributes are visible.
The
VX_GETEXT
ioctl returns a 0
if the extent information
is successfully obtained.
If the operation fails,
the return value is -1
and the external variable
errno
will be a general DIAGNOSTIC.
- VX_GETFSOPT
Get file system options.
The argument
arg
should be a pointer to an
int.
This command may be used
by any user who can open the root inode
on the file system.
The options returned in
arg
are:
- VX_FSO_BLKCLEAR
Indicates that all newly allocated blocks
will be guaranteed to contain all zeros.
(See the
blkclear
mount option of
mount_vxfs(1M)).
- VX_FSO_CACHE_CLOSESYNC
Indicates that any non-logged changes
to the inode or data
will be flushed to disk
when the file is closed.
(See the
mincache=closesync
mount option of
mount_vxfs(1M)).
- VX_FSO_CACHE_DIRECT
Indicates that any non-synchronous I/O
will be handled as if the
VX_DIRECT
cache advisory had been set on the file.
Also,
any non-logged changes
to the inode or data
will be flushed to disk
when the file is closed.
(See the
mincache=direct
mount option of
mount_vxfs(1M)).
- VX_FSO_CACHE_DSYNC
Indicates that any writes
that don't have either
O_SYNC
or the
VX_DIRECT
advisory set
will be handled as if the
VX_DSYNC
advisory had been set on the file.
Also,
any non-logged changes
to the inode or data
will be flushed to disk
when the file is closed.
(See the
mincache=dsync
mount option of
mount_vxfs(1M)).
- VX_FSO_NODATAINLOG
Indicates that intent logging
of user data for synchronous writes
is disabled.
(See the
nodatainlog
mount option of
mount_vxfs(1M)).
- VX_FSO_NOLOG
Indicates that intent logging
of structural changes to the file system
is disabled.
(See the
nolog
mount option of
mount_vxfs(1M)).
- VX_FSO_OSYNC_CLOSESYNC
Indicates that any non-logged changes
to the inode or data
will be flushed to disk
when a file accessed with
O_SYNC
is closed.
(See the
convosync=closesync
mount option of
mount_vxfs(1M)).
- VX_FSO_OSYNC_DIRECT
Indicates that any
O_SYNC
I/O will be handled as if the
VX_DIRECT
cache advisory had been set on the file instead.
Also,
any non-logged changes
to the inode or data
will be flushed to disk
when a file accessed with
O_SYNC
is closed.
(See the
convosync=direct
mount option of
mount_vxfs(1M)).
- VX_FSO_OSYNC_DSYNC
Indicates that any
O_SYNC
writes will be handled as if the
VX_DSYNC
cache advisory had been set on the file instead.
Also,
any non-logged changes
to the inode or data
will be flushed to disk
when a file accessed with
O_SYNC
is closed.
(See the
convosync=dsync
mount option of
mount_vxfs(1M)).
- VX_FSO_SNAPPED
Indicates that a snapshot backup
of this file system is being maintained.
- VX_FSO_SNAPSHOT
Indicates that this file system
is a snapshot backup
of another file system.
- VX_FSO_VJFS
Indicates that
the VxFS Advanced package
is not installed.
The
VX_GETFSOPT
ioctl
returns a 0
if the file system options
are successfully obtained.
If the operation fails,
the return value is -1
and the external variable
errno
will be a general DIAGNOSTIC.
- VX_FREEZE
Sync then freeze the file system.
Once frozen,
all further operations
against the file system
block until a
VX_THAW
operation is received.
The argument
arg
is a timeout value
expressed in seconds.
If a
VX_THAW
operation is not received
within the specified timeout interval,
the file system will perform a
VX_THAW
operation automatically.
This command may only be used
by a user with appropriate privilege,
on the root directory of the file system.
The
VX_FREEZE
ioctl
returns a 0
if the file system
is successfully frozen.
If the operation fails,
the return value is -1
and the external variable
errno
will be a general DIAGNOSTIC.
- VX_THAW
Unblock a file system
that has been frozen by a
VX_FREEZE
operation.
The argument
arg
should be NULL.
The process that is to issue a
VX_THAW
operation
must have the root directory
of the file system open,
and must ensure
that it does not access the file system
after the file system has been frozen,
to ensure that the process itself
does not block.
This command may only be used
by a user with appropriate privilege,
on the root directory of the file system.
The
VX_THAW
ioctl
returns a 0
if the file system
is successfully unfrozen.
If the operation fails,
the return value is -1
and the external variable
errno
will be a general DIAGNOSTIC
or one of the following:
