linux-toradex.git/fs/gfs2/super.c, branch v4.9.123

GFS2: use BIT() macro

2016-08-02T17:05:27+00:00

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: Fabian Frederick 
Signed-off-by: Bob Peterson

gfs2: Lock holder cleanup

2016-06-27T14:47:09+00:00

Make the code more readable by cleaning up the different ways of
initializing lock holders and checking for initialized lock holders:
mark lock holders as uninitialized by setting the holder's glock to NULL
(gfs2_holder_mark_uninitialized) instead of zeroing out the entire
object or using a separate flag.  Recognize initialized holders by their
non-NULL glock (gfs2_holder_initialized).  Don't zero out holder objects
which are immeditiately initialized via gfs2_holder_init or
gfs2_glock_nq_init.

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Bob Peterson

don't bother with ->d_inode->i_sb - it's always equal to ->d_sb

2016-04-10T21:11:51+00:00

... and neither can ever be NULL

Signed-off-by: Al Viro

GFS2: Check if iopen is held when deleting inode

2016-01-14T13:47:42+00:00

This patch fixes an error condition in which an inode is partially
created in gfs2_create_inode() but then some error is discovered,
which causes it to fail and call iput() before the iopen glock is
created or held. In that case, gfs2_delete_inode would try to
unlock an iopen glock that doesn't yet exist. Therefore, we test
its holder (which must exist) for the HIF_HOLDER bit before trying
to dq it.

Signed-off-by: Bob Peterson 
Acked-by: Steven Whitehouse

GFS2: Truncate address space mapping when deleting an inode

2015-12-18T16:52:21+00:00

In function gfs2_delete_inode() we write and flush the mapping for
a glock, among other things. We truncate the mapping for the inode,
but we never truncate the mapping for the glock. This patch makes it
also truncate the metamapping. This avoid cases where the glock is
reused by another process who is trying to recreate an inode in its
place using the same block.

Signed-off-by: Bob Peterson 
Acked-by: Steven Whitehouse

GFS2: Wait for iopen glock dequeues

2015-12-18T16:49:22+00:00

This patch changes every glock_dq for iopen glocks into a dq_wait.
This makes sure that iopen glocks do not outlive the inode itself.
In turn, that ensures that anyone trying to unlink the glock will
be able to find the inode when it receives a remote iopen callback.

Signed-off-by: Bob Peterson 
Acked-by: Steven Whitehouse

gfs2: clear journal live bit in gfs2_log_flush

2015-12-14T18:19:41+00:00

When gfs2 was unmounting filesystems or changing them to read-only it
was clearing the SDF_JOURNAL_LIVE bit before the final log flush.  This
caused a race.  If an inode glock got demoted in the gap between
clearing the bit and the shutdown flush, it would be unable to reserve
log space to clear out the active items list in inode_go_sync, causing an
error in inode_go_inval because the glock was still dirty.

To solve this, the SDF_JOURNAL_LIVE bit is now cleared inside the
shutdown log flush.  This means that, because of the locking on the log
blocks, either inode_go_sync will be able to reserve space to clean the
glock before the shutdown flush, or the shutdown flush will clean the
glock itself, before inode_go_sync fails to reserve the space. Either
way, the glock will be clean before inode_go_inval.

Signed-off-by: Benjamin Marzinski 
Signed-off-by: Bob Peterson

gfs2: change gfs2 readdir cookie

2015-12-14T18:19:37+00:00

gfs2 currently returns 31 bits of filename hash as a cookie that readdir
uses for an offset into the directory.  When there are a large number of
directory entries, the likelihood of a collision goes up way too
quickly.  GFS2 will now return cookies that are guaranteed unique for a
while, and then fail back to using 30 bits of filename hash.
Specifically, the directory leaf blocks are divided up into chunks based
on the minimum size of a gfs2 directory entry (48 bytes). Each entry's
cookie is based off the chunk where it starts, in the linked list of
leaf blocks that it hashes to (there are 131072 hash buckets). Directory
entries will have unique names until they take reach chunk 8192.
Assuming the largest filenames possible, and the least efficient spacing
possible, this new method will still be able to return unique names when
the previous method has statistically more than a 99% chance of a
collision.  The non-unique names it fails back to are guaranteed to not
collide with the unique names.

unique cookies will be in this format:
- 1 bit "0" to make sure the the returned cookie is positive
- 17 bits for the hash table index
- 1 bit for the mode "0"
- 13 bits for the offset

non-unique cookies will be in this format:
- 1 bit "0" to make sure the the returned cookie is positive
- 17 bits for the hash table index
- 1 bit for the mode "1"
- 13 more bits of the name hash

Another benefit of location based cookies, is that once a directory's
exhash table is fully extended (so that multiple hash table indexs do
not use the same leaf blocks), gfs2 can skip sorting the directory
entries until it reaches the non-unique ones, and then it only needs to
sort these. This provides a significant speed up for directory reads of
very large directories.

The only issue is that for these cookies to continue to point to the
correct entry as files are added and removed from the directory, gfs2
must keep the entries at the same offset in the leaf block when they are
split (see my previous patch). This means that until all the nodes in a
cluster are running with code that will split the directory leaf blocks
this way, none of the nodes can use the new cookie code. To deal with
this, gfs2 now has the mount option loccookie, which, if set, will make
it return these new location based cookies.  This option must not be set
until all nodes in the cluster are at least running this version of the
kernel code, and you have guaranteed that there are no outstanding
cookies required by other software, such as NFS.

gfs2 uses some of the extra space at the end of the gfs2_dirent
structure to store the calculated readdir cookies. This keeps us from
needing to allocate a seperate array to hold these values.  gfs2
recomputes the cookie stored in de_cookie for every readdir call.  The
time it takes to do so is small, and if gfs2 expected this value to be
saved on disk, the new code wouldn't work correctly on filesystems
created with an earlier version of gfs2.

One issue with adding de_cookie to the union in the gfs2_dirent
structure is that it caused the union to align itself to a 4 byte
boundary, instead of its previous 2 byte boundary. This changed the
offset of de_rahead. To solve that, I pulled de_rahead out of the union,
since it does not need to be there.

Signed-off-by: Benjamin Marzinski 
Signed-off-by: Bob Peterson

GFS2: Update master statfs buffer with sd_statfs_spin locked

2015-12-14T18:19:28+00:00

Before this patch, function update_statfs called gfs2_statfs_change_out
to update the master statfs buffer without the sd_statfs_spin held.
In theory, another process could call gfs2_statfs_sync, which takes
the sd_statfs_spin lock and re-reads m_sc from the buffer. So there's
a theoretical timing window in which one process could write the
master statfs buffer, then another comes along and re-reads it, wiping
out the changes.

Signed-off-by: Bob Peterson

GFS2: Make rgrp reservations part of the gfs2_inode structure

2015-12-14T18:16:38+00:00

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: Bob Peterson