Signed-off-by: Alberto Bertogli <albertito@blitiri.com.ar>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

If the caller isn't planning on modifying the block group descriptors,
there's no need to pass in a pointer to a struct buffer_head.  Nuking
this saves a tiny amount of CPU time and stack space usage.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The __ext4_write_dirty_metadata() function was introduced by commit
0390131b, "ext4: Allow ext4 to run without a journal", but nothing
ever used the function, either then or since.  So let's remove it and
save a bit of space.

Cc: Frank Mayhar <fmayhar@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: Manish Katiyar <mkatiyar@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: Manish Katiyar <mkatiyar@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: Manish Katiyar <mkatiyar@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Not sure why I put this in as down_write originally; all we are
doing is walking the tree, nothing will change under us and
concurrent reads should be no problem.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

To catch filesystem bugs or corruption which could lead to the
filesystem getting severly damaged, this patch adds a facility for
tracking all of the filesystem metadata blocks by contiguous regions
in a red-black tree.  This allows quick searching of the tree to
locate extents which might overlap with filesystem metadata blocks.

This facility is also used by the multi-block allocator to assure that
it is not allocating blocks out of the system zone, as well as by the
routines used when reading indirect blocks and extents information
from disk to make sure their contents are valid.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The ext4_get_blocks() function was depending on the value of
bh_result->b_state as an input parameter to decide whether or not
update the delalloc accounting statistics by calling
ext4_da_update_reserve_space().  We now use a separate flag,
EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE, to requests this update, so that
all callers of ext4_get_blocks() can clear map_bh.b_state before
calling ext4_get_blocks() without worrying about any consistency
issues.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The static function ext4_da_get_block_write() was only used by
mpage_da_map_blocks().  So to simplify the code, merge that function
into mpage_da_map_blocks().
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Enforce that noalloc_get_block_write() is only called to map one block
at a time, and that it always is successful in finding a mapping for
given an inode's logical block block number if it is called with
create == 1.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

This adds more documentation to various internal functions in
fs/ext4/inode.c, most notably ext4_ind_get_blocks(),
ext4_da_get_block_write(), ext4_da_get_block_prep(),
ext4_normal_get_block_write().

In addition, the static function ext4_normal_get_block_write() has
been renamed noalloc_get_block_write(), since it is used in many
places far beyond ext4_normal_writepage().

Plenty of warnings have been added to the noalloc_get_block_write()
function, since the way it is used is amazingly fragile.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The functions ext4_get_blocks(), ext4_ext_get_blocks(), and
ext4_ind_get_blocks() used an ad-hoc set of integer variables used as
boolean flags passed in as arguments.  Use a single flags parameter
and a setandard set of bitfield flags instead.  This saves space on
the call stack, and it also makes the code a bit more understandable.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Another function rename for clarity's sake.  The _wrap prefix simply
confuses people, and didn't add much people trying to follow the code
paths.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The static function ext4_get_blocks_handle() is badly named.  Of
*course* it takes a handle.  Since its counterpart for extent-based
file is ext4_ext_get_blocks(), rename it to be ext4_ind_get_blocks().
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The function ext4_da_get_block_write() is called in exactly one write,
and the last argument, create, is always 1.  Remove it to simplify the
code slightly.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

On UP systems without DEBUG_SPINLOCK, ext4_is_group_locked always fails
which triggers a BUG_ON() call.
This patch fixes it by using assert_spin_locked instead.
Signed-off-by: Vincent Minet <vincent@vincent-minet.net>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

We have sb_bgl_lock() and ext4_group_info.bb_state
bit spinlock to protech group information. The later is only
used within mballoc code. Consolidate them to use sb_bgl_lock().
This makes the mballoc.c code much simpler and also avoid
confusion with two locks protecting same info.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

If the file's blocks have not yet been allocated because of delayed
allocation, the length of the extent returned by fiemap is incorrect.
This commit fixes this bug.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Carl Henrik Lunde reported and debugged this; the test for the
last allocated block was comparing bytes to blocks in this test:

	if (logical + length - 1 == EXT_MAX_BLOCK ||
	    ext4_ext_next_allocated_block(path) == EXT_MAX_BLOCK)
		flags |= FIEMAP_EXTENT_LAST;

so any extent which ended right at 4G was stopping the extent
walk.  Just replacing these values with the extent block &
length should fix it.

Also give blksize_bits a saner type, and reverse the order 
of the tests to make the more likely case tested first.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reported-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Tested-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The fiemap and get_blk_size ioctls should be enabled even for
directories.  So move it outisde file_ioctl.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Add fiemap callback for directories
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

In memory-constrained systems with many partitions, the ~68K for each
partition for the mb_history buffer can be excessive.

This patch adds a new mount option, mb_history_length, as well as a
way of setting the default via a module parameter (or via a sysfs
parameter in /sys/module/ext4/parameter/default_mb_history_length).
If the mb_history_length is set to zero, the mb_history facility is
disabled entirely.
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Move the function prototypes in group.h into ext4.h so they are all
defined in one place.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The fs/ext4/namei.h header file had only a single function
declaration, and should have never been a standalone file.  Move it
into ext4.h, where should have been from the beginning.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

There is no longer a reason for a separate ext4_sb.h header file, so
move it into ext4.h just to make life easier for developers to find
the relevant data structures and typedefs.  Should also speed up
compiles slightly, too.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

There is no longer a reason for a separate ext4_i.h header file, so
move it into ext4.h just to make life easier for developers to find
the relevant data structures and typedefs.  Should also speed up
compiles slightly, too.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

By avoiding the use of not-yet-used block groups (i.e., block groups
with the BLOCK_UNINIT flag), mballoc had a tendency to create large
files with large non-contiguous gaps.  In addition avoiding the use of
new block groups had a tendency to push regular file data into the
first block group in a flex_bg group, which slows down the speed of
e2fsck pass 2, since it has a tendency to seek much more.  For
example:

               Before Patch                       After Patch
              Time in seconds                   Time in seconds
            Real /  User/  Sys   MB/s      Real /  User/  Sys    MB/s
Pass 1      8.52 / 2.21 / 0.46  20.43      8.84 / 4.97 / 1.11   19.68
Pass 2     21.16 / 1.02 / 1.86  11.30      6.54 / 1.77 / 1.78   36.39
Pass 3      0.01 / 0.00 / 0.00 139.00      0.01 / 0.01 / 0.00  128.90
Pass 4      0.16 / 0.15 / 0.00   0.00      0.17 / 0.17 / 0.00    0.00
Pass 5      2.52 / 1.99 / 0.09   0.79      2.31 / 1.78 / 0.06    0.86
Total      32.40 / 5.11 / 2.49  12.81     17.99 / 8.75 / 2.98   23.01

This was on a sample 80 gig root filesystem which was approximately
50% full.  Note the improved e2fsck pass 2 performance, by over a
factor of 3, due to a decreased number of seeks.  (The total amount of
I/O in pass 2 was unchanged; the layout of the directory blocks was
simply much better from e2fsck's's perspective.)

Other changes as a result of this patch on this sample filesystem:

                             Before Patch    After Patch
# of non-contig files           762             779
# of non-contig directories     571             570
# of BLOCK_UNINIT bg's          307             293
# of INODE_UNINIT bg's          503             503

Out of 640 block groups, of which 333 were in use, this patch caused
an extra 14 block groups to be utilized.  The number of non-contiguous
files did go up slightly, but when measured against the 99.9% of the
files (603,154) which were contiguously allocated, this is pretty
insignificant.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andreas Dilger <adilger@sun.com>

    
Use a separate lock to protect s_groups_count and the other block
group descriptors which get changed via an on-line resize operation,
so we can stop overloading the use of lock_super().
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Use a separate lock to protect the orphan list, so we can stop
overloading the use of lock_super().
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The function ext4_mark_recovery_complete() is called from two call
paths: either (a) while mounting the filesystem, in which case there's
no danger of any other CPU calling write_super() until the mount is
completed, and (b) while remounting the filesystem read-write, in
which case the fs core has already locked the superblock.  This also
allows us to take out a very vile unlock_super()/lock_super() pair in
ext4_remount().
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

ext4_fill_super() is no longer called by read_super(), and it is no
longer called with the superblock locked.  The
unlock_super()/lock_super() is no longer present, so this comment is
entirely superfluous.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Ext4's on-line resizing adds a new block group and then, only at the
last step adjusts s_groups_count.  However, it's possible on SMP
systems that another CPU could see the updated the s_group_count and
not see the newly initialized data structures for the just-added block
group.  For this reason, it's important to insert a SMP read barrier
after reading s_groups_count and before reading any (for example) the
new block group descriptors allowed by the increased value of
s_groups_count.

Unfortunately, we rather blatently violate this locking protocol
documented in fs/ext4/resize.c.  Fortunately, (1) on-line resizes
happen relatively rarely, and (2) it seems rare that the filesystem
code will immediately try to use just-added block group before any
memory ordering issues resolve themselves.  So apparently problems
here are relatively hard to hit, since ext3 has been vulnerable to the
same issue for years with no one apparently complaining.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

By using a separate super_operations structure for filesystems that
have and don't have journals, we can simply ext4_write_super() ---
which is only needed when no journal is present --- and ext4_freeze(),
ext4_unfreeze(), and ext4_sync_fs(), which are only needed when the
journal is present.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The s_dirt flag wasn't completely handled correctly, but it didn't
really matter when journalling was enabled.  It turns out that when
ext4 runs without a journal, we don't clear s_dirt in places where we
should have, with the result that the high-level write_super()
function was writing the superblock when it wasn't necessary.

So we fix this by making ext4_commit_super() clear the s_dirt flag,
and removing many of the other places where s_dirt is manipulated.
When journalling is enabled, the s_dirt flag might be left set more
often, but s_dirt really doesn't matter when journalling is enabled.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The ext4_commit_super() function took both a struct super_block * and
a struct ext4_super_block *, but the struct ext4_super_block can be
derived from the struct super_block.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

For very large filesystems, the s_flex_groups array can get quite big.
For example, a filesystem that can be resized up to 16TB will have
8192 flex groups (assuming the default flex_bg size of 16), so the
array is 96k, which is *very* marginal for kmalloc().  On the other
hand, a 160GB filesystem without the resize_inode feature will only
require 960 bytes.  So we try to allocate the array first using
kmalloc(), and if that fails, we'll try to use vmalloc() instead.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Setting BH_Unwritten buffer_heads as BH_Mapped avoids multiple
(unnecessary) calls to get_block() during the call to the write(2)
system call.  Setting BH_Unwritten buffer heads as BH_Mapped requires
that the writepages() functions can handle BH_Unwritten buffer_heads.

After this commit, things work as follows:

ext4_ext_get_block() returns unmapped, unwritten, buffer head when
called with create = 0 for prealloc space. This makes sure we handle
the read path and non-delayed allocation case correctly.  Even though
the buffer head is marked unmapped we have valid b_blocknr and b_bdev
values in the buffer_head.

ext4_da_get_block_prep() called for block resrevation will now return
mapped, unwritten, new buffer_head for prealloc space. This avoids
multiple calls to get_block() for write to same offset. By making such
buffers as BH_New, we also assure that sub-block zeroing of buffered
writes happens correctly.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The BH_Delay and BH_Unwritten flags should never leak out to
submit_bh().  So add some BUG_ON() checks to submit_bh so we can get a
stack trace and determine how and why this might have happened.

(Note that only XFS and ext4 use these buffer head flags, and XFS does
not use submit_bh().  So this patch should only modify behavior for
ext4.)
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: linux-fsdevel@vger.kernel.org