Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

We need to make sure that existing ext3 filesystems can also avail the
new fields that have been added to the ext4 inode. We use
s_want_extra_isize and s_min_extra_isize to decide by how much we should
expand the inode. If EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE feature is set
then we expand the inode by max(s_want_extra_isize, s_min_extra_isize ,
sizeof(ext4_inode) - EXT4_GOOD_OLD_INODE_SIZE) bytes. Actually it is
still an open question about whether users should be able to set
s_*_extra_isize smaller than the known fields or not.

This patch also adds the functionality to expand inodes to include the
newly added fields. We start by trying to expand by s_want_extra_isize
bytes and if its fails we try to expand by s_min_extra_isize bytes. This
is done by changing the i_extra_isize if enough space is available in
the inode and no EAs are present. If EAs are present and there is enough
space in the inode then the EAs in the inode are shifted to make space.
If enough space is not available in the inode due to the EAs then 1 or
more EAs are shifted to the external EA block. In the worst case when
even the external EA block does not have enough space we inform the user
that some EA would need to be deleted or s_min_extra_isize would have to
be reduced.
Signed-off-by: NAndreas Dilger <adilger@clusterfs.com>
Signed-off-by: NKalpak Shah <kalpak@clusterfs.com>
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

This patch adds nanosecond timestamps for ext4. This involves adding
*time_extra fields to the ext4_inode to extend the timestamps to
64-bits.  Creation time is also added by this patch.

These extended fields will fit into an inode if the filesystem was
formatted with large inodes (-I 256 or larger) and there are currently
no EAs consuming all of the available space. For new inodes we always
reserve enough space for the kernel's known extended fields, but for
inodes created with an old kernel this might not have been the case. So
this patch also adds the EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE feature
flag(ro-compat so that older kernels can't create inodes with a smaller
extra_isize). which indicates if the fields fitting inside
s_min_extra_isize are available or not.  If the expansion of inodes if
unsuccessful then this feature will be disabled.  This feature is only
enabled if requested by the sysadmin.

None of the extended inode fields is critical for correct filesystem
operation.
Signed-off-by: NAndreas Dilger <adilger@clusterfs.com>
Signed-off-by: NKalpak Shah <kalpak@clusterfs.com>
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: NDave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

    
Propagate flags such as S_APPEND, S_IMMUTABLE, etc. from i_flags into
ext4-specific i_flags.  Quota code changes these flags on quota files
(to make it harder for sysadmin to screw himself) and these changes were
not correctly propagated into the filesystem.

(This is a forward port patch from ext3)
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

One of error path in ext4_read_inode() leaks bh since brelse is forgoten.
Signed-off-by: NKirill Korotaev <dev@openvz.org>
Acked-by: NVasily Averin <vvs@sw.ru>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Replace a lot of spaces with tabs
Signed-off-by: NDave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Remove includes of <linux/smp_lock.h> where it is not used/needed.
Suggested by Al Viro.

Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Taken from http://bugzilla.kernel.org/show_bug.cgi?id=5079

signed long ranges from -2.147.483.648 to 2.147.483.647 on x86 32bit

10000011110110100100111110111101 .. -2,082,844,739
10000011110110100100111110111101 ..  2,212,122,557 <- this currently gets
stored on the disk but when converting it to a 64bit signed long value it loses
its sign and becomes positive.

Cc: Andreas Dilger <adilger@dilger.ca>
Cc: <linux-ext4@vger.kernel.org>

Andreas says:

This patch is now treating timestamps with the high bit set as negative
times (before Jan 1, 1970).  This means we lose 1/2 of the possible range
of timestamps (lopping off 68 years before unix timestamp overflow -
now only 30 years away :-) to handle the extremely rare case of setting
timestamps into the distant past.

If we are only interested in fixing the underflow case, we could just
limit the values to 0 instead of storing negative values.  At worst this
will skew the timestamp by a few hours for timezones in the far east
(files would still show Jan 1, 1970 in "ls -l" output).

That said, it seems 32-bit systems (mine at least) allow files to be set
into the past (01/01/1907 works fine) so it seems this patch is bringing
the x86_64 behaviour into sync with other kernels.

On the plus side, we have a patch that is ready to add nanosecond timestamps
to ext3 and as an added bonus adds 2 high bits to the on-disk timestamp so
this extends the maximum date to 2242.
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Revert b46be050.  Same reasoning as for ext3.

Cc: Kirill Korotaev <dev@openvz.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ken Chen <kenneth.w.chen@intel.com>
Cc: Andrey Savochkin <saw@sw.ru>
Cc: <linux-ext4@vger.kernel.org>
Cc: Dmitriy Monakhov <dmonakhov@openvz.org>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

jbd function called instead of fs specific one.
Signed-off-by: NDmitriy Monakhov <dmonakhov@openvz.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

journal_stop() is not defined for ext4; change to ext4_journal_stop().
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

In journal=ordered or journal=data mode retry in ext4_prepare_write()
breaks the requirements of journaling of data with respect to metadata.
The fix is to call commit_write to commit allocated zero blocks before
retry.
Signed-off-by: NKirill Korotaev <dev@openvz.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ken Chen <kenneth.w.chen@intel.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

move '_hi' bits of block numbers in the larger part of the
block group descriptor structure
Signed-off-by: NAlexandre Ratchov <alexandre.ratchov@bull.net>
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

make block group descriptor larger.
Signed-off-by: NAlexandre Ratchov <alexandre.ratchov@bull.net>
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Previously when in-kernel ext4 block type is sector_t, it's only 4 bits long
under some 32bit arch (when CONFIG_LBD is not on).  So we need to check the
size of sector_t before we read 48bit long on-disk blocks to in-kernel blocks.

These checks are unnecessary now as we changed the in-kernel blocks to
unsigned longlong.
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Change ext4 in-kernel block type (ext4_fsblk_t) from sector_t to unsigned
long long.  Remove ext4 block type string micro E3FSBLK, replaced with "%llu"

[akpm@osdl.org: build fix]
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

In-kernel super block changes to support >32 bit free blocks numbers.
Signed-off-by: NLaurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAlexandre Ratchov <alexandre.ratchov@bull.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

As we are planning to support 48-bit block numbers for ext4, we need to
support 48-bit block numbers for extended attributes.  In the short term, we
can do this by reuse (on-disk) 16-bit padding (linux2.i_pad1 currently used
only by "hurd") as high order bits for xattr.  This patch basically does that.
Signed-off-by: NBadari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

On disk extents format:
/*
* this is extent on-disk structure
* it's used at the bottom of the tree
*/
struct ext3_extent {
__le32  ee_block;       /* first logical block extent covers */
__le16  ee_len;         /* number of blocks covered by extent */
__le16  ee_start_hi;    /* high 16 bits of physical block */
__le32  ee_start;       /* low 32 bigs of physical block */
};
Signed-off-by: NAlex Tomas <alex@clusterfs.com>
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Reworked from a patch by Mingming Cao and Randy Dunlap
Signed-off-By: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Mingming Cao originally did this work, and Shaggy reproduced it using some
scripts from her.
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Start of the ext4 patch series.  See Documentation/filesystems/ext4.txt for
details.

This is a simple copy of the files in fs/ext3 to fs/ext4 and
/usr/incude/linux/ext3* to /usr/include/ex4*
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NJens Axboe <axboe@suse.de>

This eliminates the i_blksize field from struct inode.  Filesystems that want
to provide a per-inode st_blksize can do so by providing their own getattr
routine instead of using the generic_fillattr() function.

Note that some filesystems were providing pretty much random (and incorrect)
values for i_blksize.

[bunk@stusta.de: cleanup]
[akpm@osdl.org: generic_fillattr() fix]
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

More white space cleanups in preparation of cloning ext4 from ext3.
Removing spaces that precede a tab.
Signed-off-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This is primarily format string fixes, with changes to ialloc.c where large
inode counts could overflow, and also pass around journal_inum as an
unsigned long, just to be pedantic about it....
Signed-off-by: NEric Sandeen <esandeen@redhat.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Remove whitespace from ext3 and jbd, before we clone ext4.

Signed-off-by: Mingming Cao<cmm@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

ext3-get-blocks support caused ~20% degrade in Sequential read
performance (tiobench). Problem is with marking the buffer boundary
so IO can be submitted right away. Here is the patch to fix it.

  2.6.18-rc6:
  -----------
  # ./iotest
  1048576+0 records in
  1048576+0 records out
  4294967296 bytes (4.3 GB) copied, 75.2726 seconds, 57.1 MB/s

  real    1m15.285s
  user    0m0.276s
  sys     0m3.884s

  2.6.18-rc6 + fix:
  -----------------
  [root@elm3a241 ~]# ./iotest
  1048576+0 records in
  1048576+0 records out
  4294967296 bytes (4.3 GB) copied, 62.9356 seconds, 68.2 MB/s

The boundary block check in ext3_get_blocks_handle needs to be adjusted
against the count of blocks mapped in this call, now that it can map
more than one block.
Signed-off-by: NSuparna Bhattacharya <suparna@in.ibm.com>
Tested-by: NBadari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

It has been reported that ext3_getblk() is not doing the right thing and
triggering following WARN():

BUG: warning at fs/ext3/inode.c:1016/ext3_getblk()
 <c01c5140> ext3_getblk+0x98/0x2a6  <c03b2806> md_wakeup_thread+0x26/0x2a
 <c01c536d> ext3_bread+0x1f/0x88  <c01cedf9> ext3_quota_read+0x136/0x1ae
 <c018b683> v1_read_dqblk+0x61/0xac  <c0188f32> dquot_acquire+0xf6/0x107
 <c01ceaba> ext3_acquire_dquot+0x46/0x68  <c01897d4> dqget+0x155/0x1e7
 <c018a97b> dquot_transfer+0x3e0/0x3e9  <c016fe52> dput+0x23/0x13e
 <c01c7986> ext3_setattr+0xc3/0x240  <c0120f66> current_fs_time+0x52/0x6a
 <c017320e> notify_change+0x2bd/0x30d  <c0159246> chown_common+0x9c/0xc5
 <c02a222c> strncpy_from_user+0x3b/0x68  <c0167fe6> do_path_lookup+0xdf/0x266
 <c016841b> __user_walk_fd+0x44/0x5a  <c01592b9> sys_chown+0x4a/0x55
 <c015a43c> vfs_write+0xe7/0x13c  <c01695d4> sys_mkdir+0x1f/0x23
 <c0102a97> syscall_call+0x7/0xb

Looking at the code, it looks like it's not handle HOLE correctly.  It ends
up returning -EIO.  Here is the patch to fix it.

If we really want to be paranoid, we can allow return values 0 (HOLE), 1
(we asked for one block) and return -EIO for more than 1 block.  But I
really don't see a reason for doing it - all we need is the block# here.
(doesn't matter how many blocks are mapped).

ext3_get_blocks_handle() returns number of blocks it mapped.  It returns 0
in case of HOLE.  ext3_getblk() should handle HOLE properly (currently its
dumping warning stack and returning -EIO).
Signed-off-by: NBadari Pulavarty <pbadari@us.ibm.com>
Acked-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

For files other than IFREG, nobh option doesn't make sense.  Modifications
to them are journalled and needs buffer heads to do that.  Without this
patch, we get kernel oops in page_buffers().
Signed-off-by: NBadari Pulavarty <pbadari@us.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The inode number out of an NFS file handle gets passed eventually to
ext3_get_inode_block() without any checking.  If ext3_get_inode_block()
allows it to trigger an error, then bad filehandles can have unpleasant
effect - ext3_error() will usually cause a forced read-only remount, or a
panic if `errors=panic' was used.

So remove the call to ext3_error there and put a matching check in
ext3/namei.c where inode numbers are read off storage.

[akpm@osdl.org: fix off-by-one error]
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NJan Kara <jack@suse.cz>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: <stable@kernel.org>
Cc: "Stephen C. Tweedie" <sct@redhat.com>
Cc: Eric Sandeen <esandeen@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Same as with already do with the file operations: keep them in .rodata and
prevents people from doing runtime patching.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Convert the ext3 in-kernel filesystem blocks to ext3_fsblk_t.  Convert the
rest of all unsigned long type in-kernel filesystem blocks to ext3_fsblk_t,
and replace the printk format string respondingly.
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Some of the in-kernel ext3 block variable type are treated as signed 4 bytes
int type, thus limited ext3 filesystem to 8TB (4kblock size based).  While
trying to fix them, it seems quite confusing in the ext3 code where some
blocks are filesystem-wide blocks, some are group relative offsets that need
to be signed value (as -1 has special meaning).  So it seem saner to define
two types of physical blocks: one is filesystem wide blocks, another is
group-relative blocks.  The following patches clarify these two types of
blocks in the ext3 code, and fix the type bugs which limit current 32 bit ext3
filesystem limit to 8TB.

With this series of patches and the percpu counter data type changes in the mm
tree, we are able to extend exts filesystem limit to 16TB.

This work is also a pre-request for the recent >32 bit ext3 work, and makes
the kernel to able to address 48 bit ext3 block a lot easier: Simply redefine
ext3_fsblk_t from unsigned long to sector_t and redefine the format string for
ext3 filesystem block corresponding.

Two RFC with a series patches have been posted to ext2-devel list and have
been reviewed and discussed:
http://marc.theaimsgroup.com/?l=ext2-devel&m=114722190816690&w=2

http://marc.theaimsgroup.com/?l=ext2-devel&m=114784919525942&w=2

Patches are tested on both 32 bit machine and 64 bit machine, <8TB ext3 and
>8TB ext3 filesystem(with the latest to be released e2fsprogs-1.39).  Tests
includes overnight fsx, tiobench, dbench and fsstress.

This patch:

Defines ext3_fsblk_t and ext3_grpblk_t, and the printk format string for
filesystem wide blocks.

This patch classifies all block group relative blocks, and ext3_fsblk_t blocks
occurs in the same function where used to be confusing before.  Also include
kernel bug fixes for filesystem wide in-kernel block variables.  There are
some fileystem wide blocks are treated as int/unsigned int type in the kernel
currently, especially in ext3 block allocation and reservation code.  This
patch fixed those bugs by converting those variables to ext3_fsblk_t(unsigned
long) type.
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Some places in ext3 multiple block allocation code (in 2.6.17-rc3) don't
handle the little endian well.  This was resulting in *wrong* block numbers
being assigned to in-memory block variables and then stored on disk
eventually.  The following patch has been verified to fix an ext3
filesystem failure when run ltp test on a 64 bit machine.

Signed-off-by; Mingming Cao <cmm@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Mingming Cao recently added multi-block allocation support for ext3,
currently used only by DIO.  I added support to map multiple blocks for
mpage_readpages().  This patch add support for ext3_get_block() to deal
with multi-block mapping.  Basically it renames ext3_direct_io_get_blocks()
as ext3_get_block().
Signed-off-by: NBadari Pulavarty <pbadari@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

- Clean up a few little layout things and comments.

- Add a WARN_ON to a case which I was wondering about.

- Tune up some inlines.

Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Now that get_block() can handle mapping multiple disk blocks, no need to have
->get_blocks().  This patch removes fs specific ->get_blocks() added for DIO
and makes it users use get_block() instead.
Signed-off-by: NBadari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add support for multiple block allocation in ext3-get-blocks().

Look up the disk block mapping and count the total number of blocks to
allocate, then pass it to ext3_new_block(), where the real block allocation is
performed.  Once multiple blocks are allocated, prepare the branch with those
just allocated blocks info and finally splice the whole branch into the block
mapping tree.
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Currently ext3_get_block() only maps or allocates one block at a time.  This
is quite inefficient for sequential IO workload.

I have posted a early implements a simply multiple block map and allocation
with current ext3.  The basic idea is allocating the 1st block in the existing
way, and attempting to allocate the next adjacent blocks on a best effort
basis.  More description about the implementation could be found here:
http://marc.theaimsgroup.com/?l=ext2-devel&m=112162230003522&w=2

The following the latest version of the patch: break the original patch into 5
patches, re-worked some logicals, and fixed some bugs.  The break ups are:

 [patch 1] Adding map multiple blocks at a time in ext3_get_blocks()
 [patch 2] Extend ext3_get_blocks() to support multiple block allocation
 [patch 3] Implement multiple block allocation in ext3-try-to-allocate
 (called via ext3_new_block()).
 [patch 4] Proper accounting updates in ext3_new_blocks()
 [patch 5] Adjust reservation window size properly (by the given number
 of blocks to allocate) before block allocation to increase the
 possibility of allocating multiple blocks in a single call.

Tests done so far includes fsx,tiobench and dbench.  The following numbers
collected from Direct IO tests (1G file creation/read) shows the system time
have been greatly reduced (more than 50% on my 8 cpu system) with the patches.

 1G file DIO write:
 	2.6.15		2.6.15+patches
 real    0m31.275s	0m31.161s
 user    0m0.000s	0m0.000s
 sys     0m3.384s	0m0.564s

 1G file DIO read:
 	2.6.15		2.6.15+patches
 real    0m30.733s	0m30.624s
 user    0m0.000s	0m0.004s
 sys     0m0.748s	0m0.380s

Some previous test we did on buffered IO with using multiple blocks allocation
and delayed allocation shows noticeable improvement on throughput and system
time.

This patch:

Add support of mapping multiple blocks in one call.

This is useful for DIO reads and re-writes (where blocks are already
allocated), also is in line with Christoph's proposal of using getblocks() in
mpage_readpage() or mpage_readpages().
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>