When extent needs to be split, btrfs_mark_extent_written truncates the extent
first, then inserts a new extent and increases the reference count.
The race happens if someone else deletes the old extent before the new extent
is inserted. The fix here is increase the reference count in advance. This race
is similar to the race in btrfs_drop_extents that was recently fixed.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
btrfs_drop_extents will drop paths and search again when it needs to
force COW of higher nodes. It was using the key it found during the last
search as the offset for the next search.
But, this wasn't always correct. The key could be from before our desired
range, and because we're dropping the path, it is possible for file's items
to change while we do the search again.
The fix here is to make sure we don't search for something smaller than
the offset btrfs_drop_extents was called with.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This makes sure the orig_start field in struct extent_map gets set
everywhere the extent_map structs are created or modified.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The decompress code doesn't take the logical offset in extent
pointer into account. If the logical offset isn't zero, data
will be decompressed into wrong pages.
The solution used here is to record the starting offset of the extent
in the file separately from the logical start of the extent_map struct.
This allows us to avoid problems inserting overlapping extents.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
When reading compressed extents, try to put pages into the page cache
for any pages covered by the compressed extent that readpages didn't already
preload.
Add an async work queue to handle transformations at delayed allocation processing
time. Right now this is just compression. The workflow is:
1) Find offsets in the file marked for delayed allocation
2) Lock the pages
3) Lock the state bits
4) Call the async delalloc code
The async delalloc code clears the state lock bits and delalloc bits. It is
important this happens before the range goes into the work queue because
otherwise it might deadlock with other work queue items that try to lock
those extent bits.
The file pages are compressed, and if the compression doesn't work the
pages are written back directly.
An ordered work queue is used to make sure the inodes are written in the same
order that pdflush or writepages sent them down.
This changes extent_write_cache_pages to let the writepage function
update the wbc nr_written count.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Make sure we keep page->mapping NULL on the pages we're getting
via alloc_page. It gets set so a few of the callbacks can do the right
thing, but in general these pages don't have a mapping.
Don't try to truncate compressed inline items in btrfs_drop_extents.
The whole compressed item must be preserved.
Don't try to create multipage inline compressed items. When we try to
overwrite just the first page of the file, we would have to read in and recow
all the pages after it in the same compressed inline items. For now, only
create single page inline items.
Make sure we lock pages in the correct order during delalloc. The
search into the state tree for delalloc bytes can return bytes before
the page we already have locked.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This patch updates btrfs-progs for fallocate support.
fallocate is a little different in Btrfs because we need to tell the
COW system that a given preallocated extent doesn't need to be
cow'd as long as there are no snapshots of it. This leverages the
-o nodatacow checks.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
When dropping middle part of an extent, btrfs_drop_extents truncates
the extent at first, then inserts a bookend extent.
Since truncation and insertion can't be done atomically, there is a small
period that the bookend extent isn't in the tree. This causes problem for
functions that search the tree for file extent item. The way to fix this is
lock the range of the bookend extent before truncation.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This patch splits the hole insertion code out of btrfs_setattr
into btrfs_cont_expand and updates btrfs_get_extent to properly
handle the case that file extent items are not continuous.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This is a large change for adding compression on reading and writing,
both for inline and regular extents. It does some fairly large
surgery to the writeback paths.
Compression is off by default and enabled by mount -o compress. Even
when the -o compress mount option is not used, it is possible to read
compressed extents off the disk.
If compression for a given set of pages fails to make them smaller, the
file is flagged to avoid future compression attempts later.
* While finding delalloc extents, the pages are locked before being sent down
to the delalloc handler. This allows the delalloc handler to do complex things
such as cleaning the pages, marking them writeback and starting IO on their
behalf.
* Inline extents are inserted at delalloc time now. This allows us to compress
the data before inserting the inline extent, and it allows us to insert
an inline extent that spans multiple pages.
* All of the in-memory extent representations (extent_map.c, ordered-data.c etc)
are changed to record both an in-memory size and an on disk size, as well
as a flag for compression.
From a disk format point of view, the extent pointers in the file are changed
to record the on disk size of a given extent and some encoding flags.
Space in the disk format is allocated for compression encoding, as well
as encryption and a generic 'other' field. Neither the encryption or the
'other' field are currently used.
In order to limit the amount of data read for a single random read in the
file, the size of a compressed extent is limited to 128k. This is a
software only limit, the disk format supports u64 sized compressed extents.
In order to limit the ram consumed while processing extents, the uncompressed
size of a compressed extent is limited to 256k. This is a software only limit
and will be subject to tuning later.
Checksumming is still done on compressed extents, and it is done on the
uncompressed version of the data. This way additional encodings can be
layered on without having to figure out which encoding to checksum.
Compression happens at delalloc time, which is basically singled threaded because
it is usually done by a single pdflush thread. This makes it tricky to
spread the compression load across all the cpus on the box. We'll have to
look at parallel pdflush walks of dirty inodes at a later time.
Decompression is hooked into readpages and it does spread across CPUs nicely.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The offset field in struct btrfs_extent_ref records the position
inside file that file extent is referenced by. In the new back
reference system, tree leaves holding references to file extent
are recorded explicitly. We can scan these tree leaves very quickly, so the
offset field is not required.
This patch also makes the back reference system check the objectid
when extents are in deleting.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This patch makes btrfs count space allocated to file in bytes instead
of 512 byte sectors.
Everything else in btrfs uses a byte count instead of sector sizes or
blocks sizes, so this fits better.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This reworks the btrfs O_DIRECT write code a bit. It had always fallen
back to buffered IO and done an invalidate, but needed to be updated
for the data=ordered code. The invalidate wasn't actually removing pages
because they were still inside an ordered extent.
This also combines the O_DIRECT/O_SYNC paths where possible, and kicks
off IO in the main btrfs_file_write loop to keep the pipe down the the
disk full as we process long writes.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This improves the comments at the top of many functions. It didn't
dive into the guts of functions because I was trying to
avoid merging problems with the new allocator and back reference work.
extent-tree.c and volumes.c were both skipped, and there is definitely
more work todo in cleaning and commenting the code.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
* Add an EXTENT_BOUNDARY state bit to keep the writepage code
from merging data extents that are in the process of being
relocated. This allows us to do accounting for them properly.
* The balancing code relocates data extents indepdent of the underlying
inode. The extent_map code was modified to properly account for
things moving around (invalidating extent_map caches in the inode).
* Don't take the drop_mutex in the create_subvol ioctl. It isn't
required.
* Fix walking of the ordered extent list to avoid races with sys_unlink
* Change the lock ordering rules. Transaction start goes outside
the drop_mutex. This allows btrfs_commit_transaction to directly
drop the relocation trees.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Btrfs had compatibility code for kernels back to 2.6.18. These have
been removed, and will be maintained in a separate backport
git tree from now on.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This patch makes the back reference system to explicit record the
location of parent node for all types of extents. The location of
parent node is placed into the offset field of backref key. Every
time a tree block is balanced, the back references for the affected
lower level extents are updated.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Drop i_mutex during the commit
Don't bother doing the fsync at all unless the dir is marked as dirtied
and needing fsync in this transaction. For directories, this means
that someone has unlinked a file from the dir without fsyncing the
file.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
File syncs and directory syncs are optimized by copying their
items into a special (copy-on-write) log tree. There is one log tree per
subvolume and the btrfs super block points to a tree of log tree roots.
After a crash, items are copied out of the log tree and back into the
subvolume. See tree-log.c for all the details.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
While dropping snapshots, walk_down_tree does most of the work of checking
reference counts and limiting tree traversal to just the blocks that
we are freeing.
It dropped and held the allocation mutex in strange and confusing ways,
this commit changes it to only hold the mutex while actually freeing a block.
The rest of the checks around reference counts should be safe without the lock
because we only allow one process in btrfs_drop_snapshot at a time. Other
processes dropping reference counts should not drop it to 1 because
their tree roots already have an extra ref on the block.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This avoids waiting for transactions with pages locked by breaking out
the code to wait for the current transaction to close into a function
called by btrfs_throttle.
It also lowers the limits for where we start throttling.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Add a couple of #if's to follow API changes.
Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The memory reclaiming issue happens when snapshot exists. In that
case, some cache entries may not be used during old snapshot dropping,
so they will remain in the cache until umount.
The patch adds a field to struct btrfs_leaf_ref to record create time. Besides,
the patch makes all dead roots of a given snapshot linked together in order of
create time. After a old snapshot was completely dropped, we check the dead
root list and remove all cache entries created before the oldest dead root in
the list.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
A large reference cache is directly related to a lot of work pending
for the cleaner thread. This throttles back new operations based on
the size of the reference cache so the cleaner thread will be able to keep
up.
Overall, this actually makes the FS faster because the cleaner thread will
be more likely to find things in cache.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This changes the reference cache to make a single cache per root
instead of one cache per transaction, and to key by the byte number
of the disk block instead of the keys inside.
This makes it much less likely to have cache misses if a snapshot
or something has an extra reference on a higher node or a leaf while
the first transaction that added the leaf into the cache is dropping.
Some throttling is added to functions that free blocks heavily so they
wait for old transactions to drop.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Stress testing was showing data checksum errors, most of which were caused
by a lookup bug in the extent_map tree. The tree was caching the last
pointer returned, and searches would check the last pointer first.
But, search callers also expect the search to return the very first
matching extent in the range, which wasn't always true with the last
pointer usage.
For now, the code to cache the last return value is just removed. It is
easy to fix, but I think lookups are rare enough that it isn't required anymore.
This commit also replaces do_sync_mapping_range with a local copy of the
related functions.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
* In btrfs_delete_inode, wait for ordered extents after calling
truncate_inode_pages. This is much faster, and more correct
* Properly clear our the PageChecked bit everywhere we redirty the page.
* Change the writepage fixup handler to lock the page range and check to
see if an ordered extent had been inserted since the improperly dirtied
page was discovered
* Wait for ordered extents outside the transaction. This isn't required
for locking rules but does improve transaction latencies
* Reduce contention on the alloc_mutex by dropping it while incrementing
refs on a node/leaf and while dropping refs on a leaf.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
It was possible for stale mappings from disk to be used instead of the
new pending ordered extent. This adds a flag to the extent map struct
to keep it pinned until the pending ordered extent is actually on disk.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
btrfs_drop_extents is always called with a range lock held on the inode.
But, it may operate on extents outside that range as it drops and splits
them.
This patch adds a per-inode mutex that is held while calling
btrfs_drop_extents and while inserting new extents into the tree. It
prevents races from two procs working against adjacent ranges in the tree.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Checksum items are not inserted until the entire ordered extent is on disk,
but individual pages might be clean and available for reclaim long before
the whole extent is on disk.
In order to allow those pages to be freed, we need to be able to search
the list of ordered extents to find the checksum that is going to be inserted
in the tree. This way if the page needs to be read back in before
the checksums are in the btree, we'll be able to verify the checksum on
the page.
This commit adds the ability to search the pending ordered extents for
a given offset in the file, and changes btrfs_releasepage to allow
ordered pages to be freed.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
btrfs_commit_transaction has to loop waiting for any writers in the
transaction to finish before it can proceed. btrfs_start_transaction
should be polite and not join a transaction that is in the process
of being finished off.
There are a few places that can't wait, basically the ones doing IO that
might be needed to finish the transaction. For them, btrfs_join_transaction
is added.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This changes the ordered data code to update i_size after the extent
is on disk. An on disk i_size is maintained in the in-memory btrfs inode
structures, and this is updated as extents finish.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Higher layers sometimes call set_page_dirty without asking the filesystem
to help. This causes many problems for the data=ordered and cow code.
This commit detects pages that haven't been properly setup for IO and
kicks off an async helper to deal with them.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The old data=ordered code would force commit to wait until
all the data extents from the transaction were fully on disk. This
introduced large latencies into the commit and stalled new writers
in the transaction for a long time.
The new code changes the way data allocations and extents work:
* When delayed allocation is filled, data extents are reserved, and
the extent bit EXTENT_ORDERED is set on the entire range of the extent.
A struct btrfs_ordered_extent is allocated an inserted into a per-inode
rbtree to track the pending extents.
* As each page is written EXTENT_ORDERED is cleared on the bytes corresponding
to that page.
* When all of the bytes corresponding to a single struct btrfs_ordered_extent
are written, The previously reserved extent is inserted into the FS
btree and into the extent allocation trees. The checksums for the file
data are also updated.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The existing throttle mechanism was often not sufficient to prevent
new writers from coming in and making a given transaction run forever.
This adds an explicit wait at the end of most operations so they will
allow the current transaction to close.
There is no wait inside file_write, inode updates, or cow filling, all which
have different deadlock possibilities.
This is a temporary measure until better asynchronous commit support is
added. This code leads to stalls as it waits for data=ordered
writeback, and it really needs to be fixed.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This allows us to delete an unlinked inode with dirty pages from the list
instead of forcing commit to write these out before deleting the inode.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Extent alloctions are still protected by a large alloc_mutex.
Objectid allocations are covered by a objectid mutex
Other btree operations are protected by a lock on individual btree nodes
Signed-off-by: Chris Mason <chris.mason@oracle.com>
These ioctls let a user application hold a transaction open while it
performs a series of operations. A final ioctl does a sync on the fs
(closing the current transaction). This is the main requirement for
Ceph's OSD to be able to keep the data it's storing in a btrfs volume
consistent, and AFAICS it works just fine. The application would do
something like
fd = ::open("some/file", O_RDONLY);
::ioctl(fd, BTRFS_IOC_TRANS_START);
/* do a bunch of stuff */
::ioctl(fd, BTRFS_IOC_TRANS_END);
or just
::close(fd);
And to ensure it commits to disk,
::ioctl(fd, BTRFS_IOC_SYNC);
When a transaction is held open, the trans_handle is attached to the
struct file (via private_data) so that it will get cleaned up if the
process dies unexpectedly. A held transaction is also ended on fsync() to
avoid a deadlock.
A misbehaving application could also deliberately hold a transaction open,
effectively locking up the FS, so it may make sense to restrict something
like this to root or something.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The extent_io writepage calls needed an extra check for discarding
pages that started on th last byte in the file.
btrfs_truncate_page needed checks to make sure the page was still part
of the file after reading it, and most importantly, needed to wait for
all IO to the page to finish before freeing the corresponding extents on
disk.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
In openSUSE 10.3, AppArmor modifies remove_suid to take a struct path
rather than just a dentry. This patch tests that the kernel is openSUSE
10.3 or newer and adjusts the call accordingly.
Debian/Ubuntu with AppArmor applied will also need a similar patch.
Maintainers of btrfs under those distributions should build on this
patch or, alternatively, alter their package descriptions to add
-DREMOVE_SUID_PATH to the compiler command line.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
- --- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ b/compat.h 2008-02-06 16:46:13.000000000 -0500
@@ -0,0 +1,15 @@
+#ifndef _COMPAT_H_
+#define _COMPAT_H_
+
+
+/*
+ * Even if AppArmor isn't enabled, it still has different prototypes.
+ * Add more distro/version pairs here to declare which has AppArmor applied.
+ */
+#if defined(CONFIG_SUSE_KERNEL)
+# if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
+# define REMOVE_SUID_PATH 1
+# endif
+#endif
+
+#endif /* _COMPAT_H_ */
- --- a/file.c 2008-02-06 11:37:39.000000000 -0500
+++ b/file.c 2008-02-06 16:46:23.000000000 -0500
@@ -37,6 +37,7 @@
#include "ordered-data.h"
#include "ioctl.h"
#include "print-tree.h"
+#include "compat.h"
static int btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes,
@@ -790,7 +791,11 @@ static ssize_t btrfs_file_write(struct f
goto out_nolock;
if (count == 0)
goto out_nolock;
+#ifdef REMOVE_SUID_PATH
+ err = remove_suid(&file->f_path);
+#else
err = remove_suid(fdentry(file));
+#endif
if (err)
goto out_nolock;
file_update_time(file);
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Christoph Hellwig