Reduce CPU time searching for free blocks by optimizing find_first_extent_bit
Fix find_free_extent to make better use of the last_alloc hint. Before it
was often finding blocks just before the hint.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This makes searches for backrefs and backref insertion much more efficient
when there are many backrefs for a single extent
Signed-off-by: Chris Mason <chris.mason@oracle.com>
There is now extent_map for mapping offsets in the file to disk and
extent_io for state tracking, IO submission and extent_bufers.
The new extent_map code shifts from [start,end] pairs to [start,len], and
pushes the locking out into the caller. This allows a few performance
optimizations and is easier to use.
A number of extent_map usage bugs were fixed, mostly with failing
to remove extent_map entries when changing the file.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
While shrinking the FS, the allocation functions need to make sure
they don't try to allocate bytes past the end of the FS.
nodatacow needed an extra check to force cows when the existing extents are
past the end of the FS.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This forces file data extents down the disk along with the metadata that
references them. The current implementation is fairly simple, and just
writes out all of the dirty pages in an inode before the commit.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The shrinking code used btrfs_next_leaf to find the next item, but
this does not cow the blocks it touches. This fix calls search_slot after
finding the next item to do appropriate cow and balancing.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The patch fixes the overlapping extent issue in shrink_extent_tree.
It checks whether there is an overlapping extent by using
find_previous_extent. If there is an overlapping extent, it setups
key.objectid and cur_byte properly.
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Signed-off-by: Chris Mason <chris.mason@oracle.com>
A number of workloads do not require copy on write data or checksumming.
mount -o nodatasum to disable checksums and -o nodatacow to disable
both copy on write and checksumming.
In nodatacow mode, copy on write is still performed when a given extent
is under snapshot.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This patch adds a new parameter 'full_scan' to 'find_search_start',
thereby 'find_search_start' can know whether 'find_free_extent' is in
full scan phrase. I feel that 'find_search_start' should skip calling
'btrfs_find_block_group' when 'find_free_extent' is in full scan
phrase. In my test on a 2GB volume, Oops occurs when space usage is
about 76%. After apply the patch, Oops occurs when space usage is
near 100%.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This patch adds a helper function 'update_pinned_extents' to
extent-tree.c. The usage of the helper function is similar to
'update_block_group', the last parameter of the function indicates
pin vs unpin.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
When pin_down_bytes decides not to pin a block because it was from the
current transaction, make sure the in memory cache of free extents is updated
Signed-off-by: Chris Mason <chris.mason@oracle.com>
find_free_extent would fail to wrap around to the start of the drive because
it was doing the enospc case checking twice in some cases, causing it
to return -ENOSPC early.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
btrfs_btree_balance_dirty is changed to pass the number of pages dirtied
for more accurate dirty throttling. This lets the VM make better decisions
about when to force some writeback.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Cache block group was overly complex and missed free blocks at the very start
of the group. This patch simplifies things significantly.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This allows the tree walking code to defrag only the newly allocated
buffers, it seems to be a good balance between perfect defragging and the
performance hit of repeatedly reallocating blocks.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This adds two types of btree defrag, a run time form that tries to
defrag recently allocated blocks in the btree when they are still in ram,
and an ioctl that forces defrag of all btree blocks.
File data blocks are not defragged yet, but this can make a huge difference
in sequential btree reads.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Before, snapshot deletion was a single atomic unit. This caused considerable
lock contention and required an unbounded amount of space. Now,
the drop_progress field in the root item is used to indicate how far along
snapshot deletion is, and to resume where it left off.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Almost none of the files including module.h need to do so,
remove them.
Include sched.h in extent-tree.c to silence a warning about cond_resched()
being undeclared.
Signed-off-by: Zach Brown <zach.brown@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The super block written during commit was not consistent with the state of
the trees. This change adds an in-memory copy of the super so that we can
make sure to write out consistent data during a commit.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Attaching below is some of the code cleanups that i came across while
reading the code.
a) alloc_path already calls init_path.
b) Mention that btrfs_inode is the in memory copy.Ext4 have ext4_inode_info as
the in memory copy ext4_inode as the disk copy
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Chris Mason