glusterfs.git/xlators/storage/posix/src/posix-handle.c, branch v3.4.4

storage/posix: do not dereference gfid symlinks before posix_handle_mkdir_hashes()

2014-05-22T11:09:16+00:00

Whenever a new directory is created, its corresponding gfid file must
also be created. This was done first calling MAKE_HANDLE_PATH() to get
the path of the gfid file, then calling posix_handle_mkdir_hashes() to
create the parent directories of the gfid, and finally creating the
soft-link.

In normal circumstances, the gfid we want to create won't exist and
MAKE_HANDLE_PATH() will return a simple path to the new gfid. However if
the volume is damaged and a self-heal is running, it is possible that we
try to create an already existing gfid. In this case, MAKE_HANDLE_PATH()
will return a path to the directory instead of the path to the gfid.

To solve this problem, every time a path to a gfid is needed, a call to
MAKE_HANDLE_ABSPATH() is made instead of the call to MAKE_HANDLE_PATH().

BUG: 1099955
Change-Id: I5bcd2b3c38d172c75946f33519e057e76d960a24
Signed-off-by: Xavier Hernandez 
Reviewed-on: http://review.gluster.org/6737
Reviewed-by: Kaleb KEITHLEY 
Tested-by: Gluster Build System

All: License message change

2012-09-13T20:19:37+00:00

License message changed for server-side, dual license GPLV2 and LGPLv3+.

Change-Id: Ia9e53061b9d2df3b3ef3bc9778dceff77db46a09
BUG: 852318
Signed-off-by: Varun Shastry 
Reviewed-on: http://review.gluster.org/3940
Tested-by: Gluster Build System 
Reviewed-by: Kaleb KEITHLEY 
Reviewed-by: Anand Avati

All: License message change

2012-08-28T10:45:06+00:00

The license message is changed to
  Copyright (c) 2008-2012 Red Hat, Inc. 
  This file is part of GlusterFS.

  This file is licensed to you under your choice of the GNU Lesser
  General Public License, version 3 or any later version (LGPLv3 or
  later), or the GNU General Public License, version 2 (GPLv2), in all
  cases as published by the Free Software Foundation.

Change-Id: I07d2b63ed5fbbbd1884f1e74f2dd56013d15b0f4
BUG: 852318
Signed-off-by: Varun Shastry 
Reviewed-on: http://review.gluster.org/3858
Tested-by: Gluster Build System 
Reviewed-by: Vijay Bellur

posix: avoid unnecessary strncpy

2012-07-02T22:29:58+00:00

When strlen(SRC) < LEN, using strncpy is misleading.
Use strcpy instead.

Change-Id: I76832353dc415de99f0583d085d5c2444d5fe8b0
BUG: 789278
Signed-off-by: Jim Meyering 
Reviewed-on: http://review.gluster.com/3587
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati

Use linkat(2) when linking on symlink

2012-06-05T17:46:25+00:00

link(2) behavior is not standardized when it comes to symlink. BSD
links to the symlink target (and fails if it does not exist),
Linux links to the symlink itself. Use linkat(2) instead of link(2)
in order to get a portable behavior.

BUG: 764655
Change-Id: If7f6f17b48a4ccf8827c3795ec147306df6b5542
Signed-off-by: Emmanuel Dreyfus 
Reviewed-on: http://review.gluster.com/3507
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati

storage/posix: Move landfill inside .glusterfs

2012-05-31T23:52:44+00:00

Change-Id: Ia2944f891dd62e72f3c79678c3a1fed389854a90
BUG: 811970
Signed-off-by: Pranith Kumar K 
Reviewed-on: http://review.gluster.com/3158
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati

NetBSD build fixes

2012-04-24T04:29:03+00:00

Signed-off-by: Emmanuel Dreyfus 

Change-Id: I8f9aabeadd2f842521a82e59594115bd80155d68
BUG: 2923
Signed-off-by: Emmanuel Dreyfus 
Reviewed-on: http://review.gluster.com/3053
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati

posix: handle some internal behavior in posix_mknod()

2012-02-17T06:48:57+00:00

assume a case of link() systemcall, which is handled in distribute by
creating a 'linkfile' in hashed subvolume, if the 'oldloc' is present
in different subvolume. we have same 'gfid' for the linkfile as that
of file for consistency. Now, a file with multiple hardlinks, we may
end up with 'hardlinked' linkfiles. dht create linkfile using 'mknod()'
fop, and as now posix_mknod() is not equipped to handle this situation.

this patch fixes the situation by looking at the 'internal' key set in
the dictionary to differentiate the call which originates from inside
with regular system calls.

Change-Id: Ibff7c31f8e0c8bdae035c705c93a295f080ff985
BUG: 763844
Signed-off-by: Amar Tumballi 
Reviewed-on: http://review.gluster.com/2755
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati

core: GFID filehandle based backend and anonymous FDs

2012-01-20T13:03:42+00:00

1. What
--------
This change introduces an infrastructure change in the filesystem
which lets filesystem operation address objects (inodes) just by its
GFID. Thus far GFID has been a unique identifier of a user-visible
inode. But in terms of addressability the only mechanism thus far has
been the backend filesystem path, which could be derived from the
GFID only if it was cached in the inode table along with the entire set
of dentry ancestry leading up to the root.

This change essentially decouples addressability from the namespace. It
is no more necessary to be aware of the parent directory to address a
file or directory.

2. Why
-------
The biggest use case for such a feature is NFS for generating
persistent filehandles. So far the technique for generating filehandles
in NFS has been to encode path components so that the appropriate
inode_t can be repopulated into the inode table by means of a recursive
lookup of each component top-down.

Another use case is the ability to perform more intelligent self-healing
and rebalancing of inodes with hardlinks and also to detect renames.

A derived feature from GFID filehandles is anonymous FDs. An anonymous FD
is an internal USABLE "fd_t" which does not map to a user opened file
descriptor or to an internal ->open()'d fd. The ability to address a file
by the GFID eliminates the need to have a persistent ->open()'d fd for the
purpose of avoiding the namespace. This improves NFS read/write performance
significantly eliminating open/close calls and also fixes some of today's
limitations (like keeping an FD open longer than necessary resulting
in disk space leakage)

3. How
-------

At each storage/posix translator level, every file is hardlinked inside
a hidden .glusterfs directory (under the top level export) with the name
as the ascii-encoded standard UUID format string. For reasons of performance
and scalability there is a two-tier classification of those hardlinks
under directories with the initial parts of the UUID string as the directory
names.

For directories (which cannot be hardlinked), the approach is to use a symlink
which dereferences the parent GFID path along with basename of the directory.
The parent GFID dereference will in turn be a dereference of the grandparent
with the parent's basename, and so on recursively up to the root export.

4. Development
---------------

4a. To leverage the ability to address an inode by its GFID, the technique is
to perform a "nameless lookup". This means, to populate a loc_t structure as:

loc_t {
   pargfid: NULL
   parent: NULL
   name: NULL
   path: NULL
   gfid: GFID to be looked up [out parameter]
   inode: inode_new () result [in parameter]
}

and performing such lookup will return in its callback an inode_t
populated with the right contexts and a struct iatt which can be
used to perform an inode_link () on the inode (without a parent and
basename). The inode will now be hashed and linked in the inode table
and findable via inode_find().

A fundamental change moving forward is that the primary fields in a
loc_t structure are now going to be (pargfid, name) and (gfid) depending
on the kind of FOP. So far path had been the primary field for operations.
The remaining fields only serve as hints/helpers.

4b. If read/write is to be performed on an inode_t, the approach so far
has been to: fd_create(), STACK_WIND(open, fd), fd_bind (in callback) and
then perform STACK_WIND(read, fd) etc. With anonymous fds now you can do
fd_anonymous (inode), STACK_WIND (read, fd). This results in great boost
in performance in the inbuilt NFS server.

5. Misc
-------
The inode_ctx_put[2] has been renamed to inode_ctx_set[2] to be consistent
with the rest of the codebase.

Change-Id: Ie4629edf6bd32a595f4d7f01e90c0a01f16fb12f
BUG: 781318
Reviewed-on: http://review.gluster.com/669
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati