Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

It turns out that commit 3229c18c0d6b2 'Fixes to "Implement iomap for
block_map"' introduced another bug in gfs2_iomap_begin that can cause
gfs2_block_map to set bh->b_size of an actual buffer to 0.  This can
lead to arbitrary incorrect behavior including crashes or disk
corruption.  Revert the incorrect part of that commit.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

It turns out that commit 3974320c "Implement iomap for block_map"
introduced a few bugs that trigger occasional failures with xfstest
generic/476:

In gfs2_iomap_begin, we jump to do_alloc when we determine that we are
beyond the end of the allocated metadata (height > ip->i_height).
There, we can end up calling hole_size with a metapath that doesn't
match the current metadata tree, which doesn't make sense.  After
untangling the code at do_alloc, fix this by checking if the block we
are looking for is within the range of allocated metadata.

In addition, add a BUG() in case gfs2_iomap_begin is accidentally called
for reading stuffed files: this is handled separately.  Make sure we
don't truncate iomap->length for reads beyond the end of the file; in
that case, the entire range counts as a hole.

Finally, revert to taking a bitmap write lock when doing allocations.
It's unclear why that change didn't lead to any failures during testing.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Add a small inline function for computing the maximum size of a stuffed
inode instead of open coding that in several places throughout the code.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Implement the top-level bits of punching a hole into a file.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Add an upper bound to the range of blocks to deallocate blocks to
function trunc_dealloc so that this function can be used for truncating
a file as well as for punching a hole into a file.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Pull the code for computing the range of metapointers to iterate out of
gfs2_metapath_ra (for readahead), sweep_bh_for_rgrps (for deallocating
metapointers within a block), and trunc_dealloc (for walking the
metadata tree).

In sweep_bh_for_rgrps, move the code for looking up the resource group
descriptor of the current resource group out of the inner loop.  The
metatype check moves to trunc_dealloc.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Turn gfs2_block_truncate_page into a function that zeroes a range within
a block rather than only the end of a block.  This will be used for
cleaning the end of the first partial block and the start of the last
partial block when punching a hole in a file.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

In rare cases, the current non-recursive delete algorithm doesn't
deallocate empty intermediary indirect blocks.  This should have very
little practical effect, but deallocating all blocks correctly should
still be preferable as it is cleaner and easier to validate.

The fix consists of using the first block to deallocate to compute the
start marker of the truncate point instead of the last block that needs
to be kept.  With that change, computing which indirect blocks are still
needed becomes relatively easy.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

The metadata read-ahead algorithm broke when switching from recursive to
non-recursive delete: the current algorithm reads ahead blocks at height
N - 1 while deallocating the blocks at hight N.  However, deallocating
the blocks at height N requires a complete walk of the metadata tree,
not only down to height N - 1.  Consequently, all blocks below height
N - 1 will be accessed without read-ahead.

Fix this by issuing read-aheads as early as possible, after each
metapath lookup.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Split out the entire lookup loop from lookup_metapath and
fillup_metapath.  Make both functions return the actual height in
mp->mp_aheight, and return 0 on success.  Handle lookup errors properly
in trunc_dealloc.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

First, this function truncates the file in chunks.  When the original
file size isn't block aligned, each chunk that is truncated will remain
be misaligned.  This is inefficient.

Second, this function doesn't recognize where holes are, so it loops
through them.  For each chunk of a hole, it creates a new transaction.
At least avoid creating another transactions whe the current one is
still empty.  (An better fix would be to skip large holes, of course.)
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Document when to use gfs2_blk2rgrpd for "inexact" resource group
matching.  Based on that, fix an incorrect use of gfs2_blk2rgrpd in
sweep_bh_for_rgrps.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

This patch implements iomap for block mapping, and switches the
block_map function to use it under the covers.

The additional IOMAP_F_BOUNDARY iomap flag indicates when iomap has
reached a "metadata boundary" and fetching the next mapping is likely to
incur an additional I/O.  This flag is used for setting the bh buffer
boundary flag.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>

This patch eliminates height parameters from function gfs2_bmap_alloc.
Function find_metapath determines the metapath's "find height", also
known as the desired height. Function lookup_metapath determines the
metapath's "actual height", previously known as starting height or
sheight. Function gfs2_bmap_alloc now gets both height values from
the metapath. This simplification was done as a step toward switching
the block_map functions to using iomap. The bh_map responsibilities
are also removed from function gfs2_bmap_alloc for the same reason.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>

Add a comment about the logical block size for directories.  Rename
"bsize" in gfs2_block_map to "factor".  Fix a typo in the description of
metaptr1.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Before this patch if you truncated a file to a smaller size it
wasn't freeing all the blocks properly. There are two reasons.

First, the metapath comparison was not comparing previous heights.
I added a function, mp_eq_to_hgt, which checks the metapath at
all heights prior to the target height.

Second, in function find_nonnull_ptr, it needed to zero out all
pointers for heights following the target height. Translated into
decimal integer terms, this way a number like 299, when incremented,
becomes 300, not 399. The 2 gets incremented to 3, and the following
digits need to be reset.

These two things allow the truncate state machine to properly find
the blocks it needs to delete.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

When gfs2 does metadata I/O, only REQ_META is used as a metadata hint of
the bio. But flag REQ_META is just a hint for block trace, not for block
layer code to handle a bio as metadata request.

For some of metadata I/Os of gfs2, A REQ_PRIO flag on the metadata bio
would be very informative to block layer code. For example, if bcache is
used as a I/O cache for gfs2, it will be possible for bcache code to get
the hint and cache the pre-fetched metadata blocks on cache device. This
behavior may be helpful to improve metadata I/O performance if the
following requests hit the cache.

Here are the locations in gfs2 code where a REQ_PRIO flag should be added,
- All places where REQ_READAHEAD is used, gfs2 code uses this flag for
  metadata read ahead.
- In gfs2_meta_rq() where the first metadata block is read in.
- In gfs2_write_buf_to_page(), read in quota metadata blocks to have them
  up to date.
These metadata blocks are probably to be accessed again in future, adding
a REQ_PRIO flag may have bcache to keep such metadata in fast cache
device. For system without a cache layer, REQ_PRIO can still provide hint
to block layer to handle metadata requests more properly.
Signed-off-by: NColy Li <colyli@suse.de>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Put all remaining accesses to gl->gl_object under the
gl->gl_lockref.lock spinlock to prevent races.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Link: http://lkml.kernel.org/r/20170420161852.0492bc3f@canb.auug.org.auSigned-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Implement truncate/delete as a non-recursive algorithm. The older
algorithm was implemented with recursion to strip off each layer
at a time (going by height, starting with the maximum height.
This version tries to do the same thing but without recursion,
and without needing to allocate new structures or lists in memory.

For example, say you want to truncate a very large file to 1 byte,
and its end-of-file metapath is: 0.505.463.428. The starting
metapath would be 0.0.0.0. Since it's a truncate to non-zero, it
needs to preserve that byte, and all metadata pointing to it.
So it would start at 0.0.0.0, look up all its metadata buffers,
then free all data blocks pointed to at the highest level.
After that buffer is "swept", it moves on to 0.0.0.1, then
0.0.0.2, etc., reading in buffers and sweeping them clean.
When it gets to the end of the 0.0.0 metadata buffer (for 4K
blocks the last valid one is 0.0.0.508), it backs up to the
previous height and starts working on 0.0.1.0, then 0.0.1.1,
and so forth. After it reaches the end and sweeps 0.0.1.508,
it continues with 0.0.2.0, and so on. When that height is
exhausted, and it reaches 0.0.508.508 it backs up another level,
to 0.1.0.0, then 0.1.0.1, through 0.1.0.508. So it has to keep
marching backwards and forwards through the metadata until it's
all swept clean. Once it has all the data blocks freed, it
lowers the strip height, and begins the process all over again,
but with one less height. This time it sweeps 0.0.0 through
0.505.463. When that's clean, it lowers the strip height again
and works to free 0.505. Eventually it strips the lowest height, 0.
For a delete or truncate to 0, all metadata for all heights of
0.0.0.0 would be freed. For a truncate to 1 byte, 0.0.0.0 would
be preserved.

This isn't much different from normal integer incrementing,
where an integer gets incremented from 0000 (0.0.0.0) to 3021
(3.0.2.1). So 0000 gets increments to 0001, 0002, up to 0009,
then on to 0010, 0011 up to 0099, then 0100 and so forth. It's
just that each "digit" goes from 0 to 508 (for a total of 509
pointers) rather than from 0 to 9.

Note that the dinode will only have 483 pointers due to the
dinode structure itself.

Also note: this is just an example. These numbers (509 and 483)
are based on a standard 4K block size. Smaller block sizes will
yield smaller numbers of indirect pointers accordingly.

The truncation process is accomplished with the help of two
major functions and a few helper functions.

Functions do_strip and recursive_scan are obsolete, so removed.

New function sweep_bh_for_rgrps cleans a buffer_head pointed to
by the given metapath and height. By cleaning, I mean it frees
all blocks starting at the offset passed in metapath. It starts
at the first block in the buffer pointed to by the metapath and
identifies its resource group (rgrp). From there it frees all
subsequent block pointers that lie within that rgrp. If it's
already inside a transaction, it stays within it as long as it
can. In other words, it doesn't close a transaction until it knows
it's freed what it can from the resource group. In this way,
multiple buffers may be cleaned in a single transaction, as long
as those blocks in the buffer all lie within the same rgrp.

If it's not in a transaction, it starts one. If the buffer_head
has references to blocks within multiple rgrps, it frees all the
blocks inside the first rgrp it finds, then closes the
transaction. Then it repeats the cycle: identifies the next
unfreed block, uses it to find its rgrp, then starts a new
transaction for that set. It repeats this process repeatedly
until the buffer_head contains no more references to any blocks
past the given metapath.

Function trunc_dealloc has been reworked into a finite state
automaton. It has basically 3 active states:
DEALLOC_MP_FULL, DEALLOC_MP_LOWER, and DEALLOC_FILL_MP:

The DEALLOC_MP_FULL state implies the metapath has a full set
of buffers out to the "shrink height", and therefore, it can
call function sweep_bh_for_rgrps to free the blocks within the
highest height of the metapath. If it's just swept the lowest
level (or an error has occurred) the state machine is ended.
Otherwise it proceeds to the DEALLOC_MP_LOWER state.

The DEALLOC_MP_LOWER state implies we are finished with a given
buffer_head, which may now be released, and therefore we are
then missing some buffer information from the metapath. So we
need to find more buffers to read in. In most cases, this is
just a matter of releasing the buffer_head and moving to the
next pointer from the previous height, so it may be read in and
swept as well. If it can't find another non-null pointer to
process, it checks whether it's reached the end of a height
and needs to lower the strip height, or whether it still needs
move forward through the previous height's metadata. In this
state, all zero-pointers are skipped. From this state, it can
only loop around (once more backing up another height) or,
once a valid metapath is found (one that has non-zero
pointers), proceed to state DEALLOC_FILL_MP.

The DEALLOC_FILL_MP state implies that we have a metapath
but not all its buffers are read in. So we must proceed to read
in buffer_heads until the metapath has a valid buffer for every
height. If the previous state backed us up 3 heights, we may
need to read in a buffer, increment the height, then repeat the
process until buffers have been read in for all required heights.
If it's successful reading a buffer, and it's at the highest
height we need, it proceeds back to the DEALLOC_MP_FULL state.
If it's unable to fill in a buffer, (encounters a hole, etc.)
it tries to find another non-zero block pointer. If they're all
zero, it lowers the height and returns to the DEALLOC_MP_LOWER
state. If it finds a good non-null pointer, it loops around and
reads it in, while keeping the metapath in lock-step with the
pointers it examines.

The state machine runs until the truncation request is
satisfied. Then any transactions are ended, the quota and
statfs data are updated, and the function is complete.

Helper function metaptr1 was introduced to be an easy way to
determine the start of a buffer_head's indirect pointers.

Helper function lookup_mp_height was introduced to find a
metapath index and read in the buffer that corresponds to it.
In this way, function lookup_metapath becomes a simple loop to
call it for every height.

Helper function fillup_metapath is similar to lookup_metapath
except it can do partial lookups. If the state machine
backed up multiple levels (like 2999 wrapping to 3000) it
needs to find out the next starting point and start issuing
metadata reads at that point.

Helper function hptrs is a shortcut to determine how many
pointers should be expected in a buffer. Height 0 is the dinode
which has fewer pointers than the others.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

This patch limits the number of transaction blocks requested during
file truncates. If we have very large multi-terabyte files, and want
to delete or truncate them, they might span so many resource groups
that we overflow the journal blocks, and cause an assert failure.
By limiting the number of blocks in the transaction, we prevent this
overflow and give other running processes time to do transactions.

The limiting factor I chose is sd_log_thresh2 which is currently
set to 4/5ths of the journal. This same ratio is used in function
gfs2_ail_flush_reqd to determine when a log flush is required.
If we make the maximum value less than this, we can get into a
infinite hang whereby the log stops moving because the number of
used blocks is less than the threshold and the iterative loop
needs more, but since we're under the threshold, the log daemon
never starts any IO on the log.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

CURRENT_TIME macro is not appropriate for filesystems as it
doesn't use the right granularity for filesystem timestamps.
Use current_time() instead.

CURRENT_TIME is also not y2038 safe.

This is also in preparation for the patch that transitions
vfs timestamps to use 64 bit time and hence make them
y2038 safe. As part of the effort current_time() will be
extended to do range checks. Hence, it is necessary for all
file system timestamps to use current_time(). Also,
current_time() will be transitioned along with vfs to be
y2038 safe.

Note that whenever a single call to current_time() is used
to change timestamps in different inodes, it is because they
share the same time granularity.
Signed-off-by: NDeepa Dinamani <deepa.kernel@gmail.com>
Reviewed-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NFelipe Balbi <balbi@kernel.org>
Acked-by: NSteven Whitehouse <swhiteho@redhat.com>
Acked-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Replace 1 << value shift by more explicit BIT() macro

Also fixes two bare unsigned definitions:

WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
+		unsigned hsize = BIT(ip->i_depth);
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

These two are confusing leftover of the old world order, combining
values of the REQ_OP_ and REQ_ namespaces.  For callers that don't
special case we mostly just replace bi_rw with bio_data_dir or
op_is_write, except for the few cases where a switch over the REQ_OP_
values makes more sense.  Any check for READA is replaced with an
explicit check for REQ_RAHEAD.  Also remove the READA alias for
REQ_RAHEAD.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NMike Christie <mchristi@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This has ll_rw_block users pass in the operation and flags separately,
so ll_rw_block can setup the bio op and bi_rw flags on the bio that
is submitted.
Signed-off-by: NMike Christie <mchristi@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This has submit_bh users pass in the operation and flags separately,
so submit_bh_wbc can setup the bio op and bi_rw flags on the bio that
is submitted.
Signed-off-by: NMike Christie <mchristi@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.

This promise never materialized.  And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE.  And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special.  They are
not.

The changes are pretty straight-forward:

 - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

This patch contains automated changes generated with coccinelle using
script below.  For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.

The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.

There are few places in the code where coccinelle didn't reach.  I'll
fix them manually in a separate patch.  Comments and documentation also
will be addressed with the separate patch.

virtual patch

@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT

@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE

@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK

@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)

@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)

@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Before this patch, multi-block reservation structures were allocated
from a special slab. This patch folds the structure into the gfs2_inode
structure. The disadvantage is that the gfs2_inode needs more memory,
even when a file is opened read-only. The advantages are: (a) we don't
need the special slab and the extra time it takes to allocate and
deallocate from it. (b) we no longer need to worry that the structure
exists for things like quota management. (c) This also allows us to
remove the calls to get_write_access and put_write_access since we
know the structure will exist.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

This patch basically reverts the majority of patch 5407e242.
That patch eliminated the gfs2_qadata structure in favor of just
using the reservations structure. The problem with doing that is that
it increases the size of the reservations structure. That is not an
issue until it comes time to fold the reservations structure into the
inode in memory so we know it's always there. By separating out the
quota structure again, we aren't punishing the non-quota users by
making all the inodes bigger, requiring more slab space. This patch
creates a new slab area to allocate the quota stuff so it's managed
a little more sanely.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Use struct gfs2_alloc_parms as an argument to gfs2_quota_check()
and gfs2_quota_lock_check() to check for quota violations while
accounting for the new blocks requested by the current operation
in ap->target.

Previously, the number of new blocks requested during an operation
were not accounted for during quota_check and would allow these
operations to exceed quota. This was not very apparent since most
operations allocated only 1 block at a time and quotas would get
violated in the next operation. i.e. quota excess would only be by
1 block or so. With fallocate, (where we allocate a bunch of blocks
at once) the quota excess is non-trivial and is addressed by this
patch.
Signed-off-by: NAbhi Das <adas@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Acked-by: NSteven Whitehouse <swhiteho@redhat.com>

This patch changes some variables (especially maxlen in function
gfs2_block_map) from unsigned int to size_t. We need 64-bit arithmetic
for very large files (e.g. 1PB) where the variables otherwise get
shifted to all 0's.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Fix 2 typos and move one definition which was between function
comments and function definition (yet another kernel-doc warning)

Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This patch fixes a long standing issue in mapping the journal
extents. Most journals will consist of only a single extent,
and although the cache took account of that by merging extents,
it did not actually map large extents, but instead was doing a
block by block mapping. Since the journal was only being mapped
on mount, this was not normally noticeable.

With the updated code, it is now possible to use the same extent
mapping system during journal recovery (which will be added in a
later patch). This will allow checking of the integrity of the
journal before any reply of the journal content is attempted. For
this reason the code is moving to bmap.c, since it will be used
more widely in due course.

An exercise left for the reader is to compare the new function
gfs2_map_journal_extents() with gfs2_write_alloc_required()

Additionally, should there be a failure, the error reporting is
also updated to show more detail about what went wrong.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This patch adds a structure to contain allocation parameters with
the intention of future expansion of this structure. The idea is
that we should be able to add more information about the allocation
in the future in order to allow the allocator to make a better job
of placing the requests on-disk.

There is no functional difference from applying this patch.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

The reservation for an inode should be cleared when it is truncated so
that we can start again at a different offset for future allocations.
We could try and do better than that, by resetting the search based on
where the truncation started from, but this is only a first step.

In addition, there are three callers of gfs2_rs_delete() but only one
of those should really be testing the value of i_writecount. While
we get away with that in the other cases currently, I think it would
be better if we made that test specific to the one case which
requires it.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

truncate_pagecache() doesn't care about old size since commit
cedabed4 ("vfs: Fix vmtruncate() regression").  Let's drop it.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If a GFS2 file system is mounted with quotas and a file is grown
in such a way that its free blocks for the allocation are represented
in a secondary bitmap, GFS2 ran out of blocks in the transaction.
That resulted in "fatal: assertion "tr->tr_num_buf <= tr->tr_blocks".
This patch reserves extra blocks for the quota change so the
transaction has enough space.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>