I was noticing the slab redzone stuff going off every once and a while during
transaction aborts. This was caused by two things
1) We would walk the pending snapshots and set their error to -ECANCELED. We
don't need to do this, the snapshot stuff waits for a transaction commit and if
there is a problem we just free our pending snapshot object and exit. Doing
this was causing us to touch the pending snapshot object after the thing had
already been freed.
2) We were freeing the transaction manually with wanton disregard for it's
use_count reference counter. To fix this I cleaned up the transaction freeing
loop to either wait for the transaction commit to finish if it was in the middle
of that (since it will be cleaned and freed up there) or to do the cleanup
oursevles.
I also moved the global "kill all things dirty everywhere" stuff outside of the
transaction cleanup loop since that only needs to be done once. With this patch
I'm no longer seeing slab corruption because of use after frees. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Noticed this when forcing errors to happen during delayed ref running. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
During transaction cleanup after an abort we are just removing roots from the
ordered roots list which is incorrect. We have a BUG_ON() to make sure that the
root is still part of the ordered roots list when we put our ordered extent
which we were tripping in this case. So do like we do everywhere else and just
move it to the tail of the ordered roots list and allow the normal cleanup to
take care of stuff. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
If we abort not during a transaction commit we won't clean up anything until we
unmount. Unfortunately if we abort in the middle of writing out an ordered
extent we won't clean it up and if somebody is waiting on that ordered extent
they will wait forever. To fix this just make the transaction kthread call the
cleanup transaction stuff if it notices theres an error, and make
btrfs_end_transaction wake up the transaction kthread if there is an error.
Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
I've been testing our error paths and I was tripping the BUG_ON() in
drop_outstanding_extent because our outstanding_extents is 0 for space cache
inodes. This is because we don't reserve metadata space for these inodes since
we depend on the global block reserve for our space. To fix this we need to
make sure the DO_ACCOUNTING stuff doesn't actually call release_metadata for
space cache inodes. With this patch I'm no longer panicing. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
If we abort a transaction in the middle of a commit we weren't undoing the
intwrite locking. This patch fixes that problem.
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
A user reported a problem where they were getting csum errors when running a
balance and running systemd's journal. This is because systemd is awesome and
fallocate()'s its log space and writes into it. Unfortunately we assume that
when we read in all the csums for an extent that they are sequential starting at
the bytenr we care about. This obviously isn't the case for prealloc extents,
where we could have written to the middle of the prealloc extent only, which
means the csum would be for the bytenr in the middle of our range and not the
front of our range. Fix this by offsetting the new bytenr we are logging to
based on the original bytenr the csum was for. With this patch I no longer see
the csum errors I was seeing. Thanks,
Cc: stable@vger.kernel.org
Reported-by: Chris Murphy <lists@colorremedies.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
In extent-tree.c:btrfs_write_dirty_block_groups(), if the call to
write_one_cache_group() failed, we would return without putting
the block group first.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Currently the fs sync function (super.c:btrfs_sync_fs()) doesn't
wait for delayed work to finish before returning success to the
caller. This change fixes this, ensuring that there's no data loss
if a power failure happens right after fs sync returns success to
the caller and before the next commit happens.
Steps to reproduce the data loss issue:
$ mkfs.btrfs -f /dev/sdb3
$ mount /dev/sdb3 /mnt/btrfs
$ perl -e '$d = ("\x41" x 6001); open($f,">","/mnt/btrfs/foobar"); print $f $d; close($f);' && btrfs fi sync /mnt/btrfs
Right after the btrfs fi sync command (a second or 2 for example), power
off the machine and reboot it. The file will be empty, as it can be verified
after mounting the filesystem and through btrfs-debug-tree:
$ btrfs-debug-tree /dev/sdb3 | egrep '\(257 INODE_ITEM 0\) itemoff' -B 3 -A 8
item 3 key (256 DIR_INDEX 2) itemoff 3751 itemsize 36
location key (257 INODE_ITEM 0) type FILE
namelen 6 datalen 0 name: foobar
item 4 key (257 INODE_ITEM 0) itemoff 3591 itemsize 160
inode generation 7 transid 7 size 0 block group 0 mode 100644 links 1
item 5 key (257 INODE_REF 256) itemoff 3575 itemsize 16
inode ref index 2 namelen 6 name: foobar
checksum tree key (CSUM_TREE ROOT_ITEM 0)
leaf 29429760 items 0 free space 3995 generation 7 owner 7
fs uuid 6192815c-af2a-4b75-b3db-a959ffb6166e
chunk uuid b529c44b-938c-4d3d-910a-013b4700bcae
uuid tree key (UUID_TREE ROOT_ITEM 0)
After this patch, the data loss no longer happens after a power failure and
btrfs-debug-tree shows:
$ btrfs-debug-tree /dev/sdb3 | egrep '\(257 INODE_ITEM 0\) itemoff' -B 3 -A 8
item 3 key (256 DIR_INDEX 2) itemoff 3751 itemsize 36
location key (257 INODE_ITEM 0) type FILE
namelen 6 datalen 0 name: foobar
item 4 key (257 INODE_ITEM 0) itemoff 3591 itemsize 160
inode generation 6 transid 6 size 6001 block group 0 mode 100644 links 1
item 5 key (257 INODE_REF 256) itemoff 3575 itemsize 16
inode ref index 2 namelen 6 name: foobar
item 6 key (257 EXTENT_DATA 0) itemoff 3522 itemsize 53
extent data disk byte 12845056 nr 8192
extent data offset 0 nr 8192 ram 8192
extent compression 0
checksum tree key (CSUM_TREE ROOT_ITEM 0)
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
In inode.c:btrfs_orphan_add() if we failed to insert the orphan
item, we would return without decrementing the orphan count that
we just incremented before attempting the insertion, leaving the
orphan inode count wrong.
In inode.c:btrfs_orphan_del(), we were decrementing the inode
orphan count if the bit BTRFS_INODE_ORPHAN_META_RESERVED was set,
which is logically wrong because it should be decremented if the
bit BTRFS_INODE_HAS_ORPHAN_ITEM was set - after all we increment
the count when we set the bit BTRFS_INODE_HAS_ORPHAN_ITEM elsewhere.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Similar to ocfs2, btrfs also supports that extents can be shared by
different inodes, and there are some userspace tools requesting
for this kind of 'space shared infomation'.[1]
ocfs2 uses flag FIEMAP_EXTENT_SHARED, so does btrfs.
[1]: http://thr3ads.net/ocfs2-devel/2010/09/489052-PATCH-3-3-shared-du-using-fiemap-to-figure-up-the-shared-extents-per-file-and-the-footprint-in
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Not used for anything, and removing it avoids caller's need to
allocate a path structure.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
We're doing a unnecessary extra lookup of the ino cache's
inode when we already have it (and holding a reference)
during the process of saving the ino cache contents to disk.
Therefore remove this extra lookup.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
While running some snashot aware defrag tests I noticed I was panicing every
once and a while in key_search. This is because of the optimization that says
if we find a key at slot 0 it will be at slot 0 all the way down the rest of the
tree. This isn't the case for btrfs_search_old_slot since it will likely replay
changes to a buffer if something has changed since we took our sequence number.
So short circuit this optimization by setting prev_cmp to -1 every time we call
key_search so we will do our normal binary search. With this patch I am no
longer seeing the panics I was seeing before. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
While looking at somebodys corruption I became completely convinced that
btrfs_split_item was broken, so I wrote this test to verify that it was working
as it was supposed to. Thankfully it appears to be working as intended, so just
add this test to make sure nobody breaks it in the future. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Remove unused eb parameter from btrfs_item_nr
Signed-off-by: Ross Kirk <ross.kirk@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
It is not necessary to store the NULL byte in a symlink inline file
extent. There's currently no code that requires the NULL byte to be
present in the extent. This change also doesn't break file format
compatibility nor the send/receive feature.
The VFS also doesn't need the NULL byte to be present in the extent,
as it reads up to inode->i_size bytes (which already excluded the NULL
byte) and sets the NULL byte for us (in fs/namei.c:page_getlink()).
So with this change we save 1 byte per symlink file extent (which is
always inlined in the btree leaf) without losing backward and forward
compatibility.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
The fact that btrfs_root_refs() returned 0 for the tree_root caused
bugs in the past, therefore it is set to 1 with this patch and
(hopefully) all affected code is adapted to this change.
I verified this change by temporarily adding WARN_ON() checks
everywhere where btrfs_root_refs() is used, checking whether the
logic of the code is changed by btrfs_root_refs() returning 1
instead of 0 for root->root_key.objectid == BTRFS_ROOT_TREE_OBJECTID.
With these added checks, I ran the xfstests './check -g auto'.
The two roots chunk_root and log_root_tree that are only referenced
by the superblock and the log_roots below the log_root_tree still
have btrfs_root_refs() == 0, only the tree_root is changed.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
A bit of cleanup plus some gratuitous variable renaming. I think using
structures instead of numeric offsets makes this code much more
understandable.
Also added a comment about current time range expected by
the server.
Acked-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Shirish Pargaonkar <spargaonkar@suse.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Opens on current cifs/smb2/smb3 mounts with O_DIRECT flag fail
even when caching is disabled on the mount. This was
reported by those running SMB2 benchmarks who need to
be able to pass O_DIRECT on many of their open calls to
reduce caching effects, but would also be needed by other
applications.
When mounting with forcedirectio ("cache=none") cifs and smb2/smb3
do not go through the page cache and thus opens with O_DIRECT flag
should work (when posix extensions are negotiated we even are
able to send the flag to the server). This patch fixes that
in a simple way.
The 9P client has a similar situation (caching is often disabled)
and takes the same approach to O_DIRECT support ie works if caching
disabled, but if client caching enabled it fails with EINVAL.
A followon idea for a future patch as Pavel noted, could
be that files opened with O_DIRECT could cause us to change
inode->i_fop on the fly from
cifs_file_strict_ops
to
cifs_file_direct_ops
which would allow us to support this on non-forcedirectio mounts
(cache=strict and cache=loose) as well.
Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>
Andrey reported that he was seeing cifs.ko spam the logs with messages
like this:
CIFS VFS: Unexpected lookup error -26
He was listing the root directory of a server and hitting an error when
trying to QUERY_PATH_INFO against hiberfil.sys and pagefile.sys. The
right fix would be to switch the lookup code over to using FIND_FIRST,
but until then we really don't need to report this at a level of
KERN_ERR. Convert this message over to FYI level.
Reported-by: "Andrey Shernyukov" <andreysh@nioch.nsc.ru>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Sometimes, the server will report an error that basically indicates
that it's running out of resources. These include these under SMB1:
NT_STATUS_NO_MEMORY
NT_STATUS_SECTION_TOO_BIG
NT_STATUS_TOO_MANY_PAGING_FILES
...and this one under SMB2:
STATUS_NO_MEMORY
Currently, this gets mapped to ENOMEM by the client, but that's
confusing as an ENOMEM error is typically an indicator that the
client is out of memory.
Change these errors to instead map to EREMOTEIO to indicate that
the problem is actually server-side and not on the client.
Reported-by: "ISHIKAWA,chiaki" <ishikawa@yk.rim.or.jp>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Now we treat any reparse point as a symbolic link and map it to a Unix
one that is not true in a common case due to many reparse point types
supported by SMB servers.
Distinguish reparse point types into two groups:
1) that can be accessed directly through a reparse point
(junctions, deduplicated files, NFS symlinks);
2) that need to be processed manually (Windows symbolic links, DFS);
and map only Windows symbolic links to Unix ones.
Cc: <stable@vger.kernel.org>
Acked-by: Jeff Layton <jlayton@redhat.com>
Reported-and-tested-by: Joao Correia <joaomiguelcorreia@gmail.com>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>
o Changes from v1
Use find_next(_zero)_bit suggested by jg.kim
When f2fs issues discard command, if segment is contiguous,
let's issue more large segment to gather adjacent segments.
** blktrace **
179,1 0 5859 42.619023770 971 C D 131072 + 2097152 [0]
179,1 0 33665 108.840475468 971 C D 2228224 + 2494464 [0]
179,1 0 33671 109.131616427 971 C D 14909440 + 344064 [0]
179,1 0 33677 109.137100677 971 C D 15261696 + 4096 [0]
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
NFSv4 uses leases to guarantee that clients can cache metadata as well
as data.
Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: David Howells <dhowells@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We'll need the same logic for rename and link.
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We need to break delegations on any operation that changes the set of
links pointing to an inode. Start with unlink.
Such operations also hold the i_mutex on a parent directory. Breaking a
delegation may require waiting for a timeout (by default 90 seconds) in
the case of a unresponsive NFS client. To avoid blocking all directory
operations, we therefore drop locks before waiting for the delegation.
The logic then looks like:
acquire locks
...
test for delegation; if found:
take reference on inode
release locks
wait for delegation break
drop reference on inode
retry
It is possible this could never terminate. (Even if we take precautions
to prevent another delegation being acquired on the same inode, we could
get a different inode on each retry.) But this seems very unlikely.
The initial test for a delegation happens after the lock on the target
inode is acquired, but the directory inode may have been acquired
further up the call stack. We therefore add a "struct inode **"
argument to any intervening functions, which we use to pass the inode
back up to the caller in the case it needs a delegation synchronously
broken.
Cc: David Howells <dhowells@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We'll be using dentry->d_inode in one more place.
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Implement NFSv4 delegations at the vfs level using the new FL_DELEG lock
type.
Note nfsd is the only delegation user and is only using read
delegations. Warn on any attempt to set a write delegation for now.
We'll come back to that case later.
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
For now FL_DELEG is just a synonym for FL_LEASE. So this patch doesn't
change behavior.
Next we'll modify break_lease to treat FL_DELEG leases differently, to
account for the fact that NFSv4 delegations should be broken in more
situations than Windows oplocks.
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
A read delegation is used by NFSv4 as a guarantee that a client can
perform local read opens without informing the server.
The open operation takes the last component of the pathname as an
argument, thus is also a lookup operation, and giving the client the
above guarantee means informing the client before we allow anything that
would change the set of names pointing to the inode.
Therefore, we need to break delegations on rename, link, and unlink.
We also need to prevent new delegations from being acquired while one of
these operations is in progress.
We could add some completely new locking for that purpose, but it's
simpler to use the i_mutex, since that's already taken by all the
operations we care about.
The single exception is rename. So, modify rename to take the i_mutex
on the file that is being renamed.
Also fix up lockdep and Documentation/filesystems/directory-locking to
reflect the change.
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
I_MUTEX_QUOTA is now just being used whenever we want to lock two
non-directories. So the name isn't right. I_MUTEX_NONDIR2 isn't
especially elegant but it's the best I could think of.
Also fix some outdated documentation.
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reserve I_MUTEX_PARENT and I_MUTEX_CHILD for locking of actual
directories.
(Also I_MUTEX_QUOTA isn't really a meaningful name for this locking
class any more; fixed in a later patch.)
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We want to do this elsewhere as well.
Also catch any attempts to use it for directories (where this ordering
would conflict with ancestor-first directory ordering in lock_rename).
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Dave Chinner <david@fromorbit.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Suppose we're given the filehandle for a directory whose closest
ancestor in the dcache is its Nth ancestor.
The main loop in reconnect_path searches for an IS_ROOT ancestor of
target_dir, reconnects that ancestor to its parent, then recommences the
search for an IS_ROOT ancestor from target_dir.
This behavior is quadratic in N. And there's really no need to restart
the search from target_dir each time: once a directory has been looked
up, it won't become IS_ROOT again. So instead of starting from
target_dir each time, we can continue where we left off.
This simplifies the code and improves performance on very deep directory
heirachies. (I can't think of any reason anyone should need heirarchies
a hundred or more deep, but the performance improvement may be valuable
if only to limit damage in case of abuse.)
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Replace another unhelpful acronym.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Also replace 3 easily-confused three-letter acronyms by more helpful
variable names.
Just cleanup, no change in functionality, with one exception: the
dentry_connected() check in the "out_reconnected" case will now only
check the ancestors of the current dentry instead of checking all the
way from target_dir. Since we've already verified connectivity up to
this dentry, that should be sufficient.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Note this counter is now being set to 0 on every pass through the loop,
so it no longer serves any useful purpose.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There are two places here where we could race with a rename or remove:
- We could find the parent, but then be removed or renamed away
from that parent directory before finding our name in that
directory.
- We could find the parent, and find our name in that parent,
but then be renamed or removed before we look ourselves up by
that name in that parent.
In both cases the concurrent rename or remove will take care of
reconnecting the directory that we're currently examining. Our target
directory should then also be connected. Check this and clear
DISCONNECTED in these cases instead of looping around again.
Note: we *do* need to check that this actually happened if we want to be
robust in the face of corrupted filesystems: a corrupted filesystem
could just return a completely wrong parent, and we want to fail with an
error in that case before starting to clear DISCONNECTED on
non-DISCONNECTED filesystems.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Once we've found any connected parent, we know all our parents are
connected--that's true even if there's a concurrent rename. May as well
clear them all at once and be done with it.
Reviewed-by: Cristoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This would indicate a nasty bug in the dcache and has never triggered in
the past 10 years as far as I know.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The DCACHE_NEED_LOOKUP case referred to here was removed with
39e3c9553f "vfs: remove
DCACHE_NEED_LOOKUP".
There are only four real_lookup() callers and all of them pass in an
unhashed dentry just returned from d_alloc.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
DCACHE_DISCONNECTED should not be cleared until we're sure the dentry is
connected all the way up to the root of the filesystem. It *shouldn't*
be cleared as soon as the dentry is connected to a parent. That will
cause bugs at least on exportable filesystems.
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
I can't for the life of me see any reason why anyone should care whether
a dentry that is never hooked into the dentry cache would need
DCACHE_DISCONNECTED set.
This originates from 4b936885ab "fs:
improve scalability of pseudo filesystems", which probably just made the
false assumption the DCACHE_DISCONNECTED was meant to be set on anything
not connected to a parent somehow.
So this is just confusing. Ideally the only uses of DCACHE_DISCONNECTED
would be in the filehandle-lookup code, which needs it to ensure
dentries are connected into the dentry tree before use.
I left d_alloc_pseudo there even though it's now equivalent to
__d_alloc(), just on the theory the name is better documentation of its
intended use outside dcache.c.
Cc: Nick Piggin <npiggin@kernel.dk>
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Every hashed dentry is either hashed in the dentry_hashtable, or a
superblock's s_anon list.
__d_drop() assumes it can determine which is the case by checking
DCACHE_DISCONNECTED; this is not true.
It is true that when DCACHE_DISCONNECTED is cleared, the dentry is not
only hashed on dentry_hashtable, but is fully connected to its parents
back to the root.
But the converse is *not* true: fs/exportfs/expfs.c:reconnect_path()
attempts to connect a directory (found by filehandle lookup) back to
root by ascending to parents and performing lookups one at a time. It
does not clear DCACHE_DISCONNECTED until it's done, and that is not at
all an atomic process.
In particular, it is possible for DCACHE_DISCONNECTED to be set on a
dentry which is hashed on the dentry_hashtable.
Instead, use IS_ROOT() to check which hash chain a dentry is on. This
*does* work:
Dentries are hashed only by:
- d_obtain_alias, which adds an IS_ROOT() dentry to sb_anon.
- __d_rehash, called by _d_rehash: hashes to the dentry's
parent, and all callers of _d_rehash appear to have d_parent
set to a "real" parent.
- __d_rehash, called by __d_move: rehashes the moved dentry to
hash chain determined by target, and assigns target's d_parent
to its d_parent, before dropping the dentry's d_lock.
Therefore I believe it's safe for a holder of a dentry's d_lock to
assume that it is hashed on sb_anon if and only if IS_ROOT(dentry) is
true.
I believe the incorrect assumption about DCACHE_DISCONNECTED was
originally introduced by ceb5bdc2d2 "fs: dcache per-bucket dcache hash
locking".
Also add a comment while we're here.
Cc: Nick Piggin <npiggin@kernel.dk>
Acked-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Josef Bacik