linux/fs/nfs
David Howells 454e2398be [PATCH] VFS: Permit filesystem to override root dentry on mount
Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.

The filesystem is then required to manually set the superblock and root dentry
pointers.  For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).

The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.

This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing.  In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.

The patch also makes the following changes:

 (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
     pointer argument and return an integer, so most filesystems have to change
     very little.

 (*) If one of the convenience function is not used, then get_sb() should
     normally call simple_set_mnt() to instantiate the vfsmount. This will
     always return 0, and so can be tail-called from get_sb().

 (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
     dcache upon superblock destruction rather than shrink_dcache_anon().

     This is required because the superblock may now have multiple trees that
     aren't actually bound to s_root, but that still need to be cleaned up. The
     currently called functions assume that the whole tree is rooted at s_root,
     and that anonymous dentries are not the roots of trees which results in
     dentries being left unculled.

     However, with the way NFS superblock sharing are currently set to be
     implemented, these assumptions are violated: the root of the filesystem is
     simply a dummy dentry and inode (the real inode for '/' may well be
     inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
     with child trees.

     [*] Anonymous until discovered from another tree.

 (*) The documentation has been adjusted, including the additional bit of
     changing ext2_* into foo_* in the documentation.

[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 07:42:45 -07:00
..
Makefile NFSv4: Allow user to set the port used by the NFSv4 callback channel 2006-01-06 14:58:52 -05:00
callback.c [PATCH] sem2mutex: fs/ 2006-03-26 08:56:55 -08:00
callback.h NFSv4: Allow user to set the port used by the NFSv4 callback channel 2006-01-06 14:58:52 -05:00
callback_proc.c NFSv4: Ensure change attribute returned by GETATTR callback conforms to spec 2006-01-06 14:58:51 -05:00
callback_xdr.c NFSv4: Kill braindead gcc warnings 2006-03-20 13:44:10 -05:00
delegation.c NFSv4: Send the delegation stateid for SETATTR calls 2006-03-20 13:44:46 -05:00
delegation.h NFSv4: Send the delegation stateid for SETATTR calls 2006-03-20 13:44:46 -05:00
dir.c NFS: remove needless check in nfs_opendir() 2006-04-19 13:06:37 -04:00
direct.c NFS,SUNRPC: Fix compiler warnings if CONFIG_PROC_FS & CONFIG_SYSCTL are unset 2006-04-19 12:43:47 -04:00
file.c NFS,SUNRPC: Fix compiler warnings if CONFIG_PROC_FS & CONFIG_SYSCTL are unset 2006-04-19 12:43:47 -04:00
idmap.c NFS: sem2mutex idmap.c 2006-03-20 13:44:11 -05:00
inode.c [PATCH] VFS: Permit filesystem to override root dentry on mount 2006-06-23 07:42:45 -07:00
iostat.h NFSv4: Fix an oops in nfs4_fill_super 2006-03-20 13:44:48 -05:00
mount_clnt.c Merge git://git.linux-nfs.org/pub/linux/nfs-2.6 2006-03-25 09:18:27 -08:00
nfs2xdr.c Merge git://git.linux-nfs.org/pub/linux/nfs-2.6 2006-03-25 09:18:27 -08:00
nfs3acl.c SUNRPC: eliminate rpc_call() 2006-03-20 13:44:23 -05:00
nfs3proc.c NFS: Cleanup of NFS read code 2006-03-20 13:44:27 -05:00
nfs3xdr.c Merge git://git.linux-nfs.org/pub/linux/nfs-2.6 2006-03-25 09:18:27 -08:00
nfs4_fs.h NFSv4: Remove requirement for machine creds for the "setclientid" operation 2006-01-06 14:58:47 -05:00
nfs4proc.c VFS: Fix another open intent Oops 2006-04-19 12:43:46 -04:00
nfs4renewd.c NFSv4: Remove requirement for machine creds for the "renew" operation 2006-01-06 14:58:47 -05:00
nfs4state.c NFSv4: SETCLIENTID_CONFIRM should handle NFS4ERR_DELAY/NFS4ERR_RESOURCE 2006-03-20 13:44:47 -05:00
nfs4xdr.c Merge git://git.linux-nfs.org/pub/linux/nfs-2.6 2006-03-25 09:18:27 -08:00
nfsroot.c [PATCH] nfsroot port= parameter fix [backport of 2.4 fix] 2006-02-07 21:00:42 -05:00
pagelist.c NFS: Fix a race with PG_private and nfs_release_page() 2006-03-20 13:44:50 -05:00
proc.c NFS: Cleanup of NFS read code 2006-03-20 13:44:27 -05:00
read.c [PATCH] mempool: use mempool_create_slab_pool() 2006-03-26 08:57:00 -08:00
symlink.c Fix nasty ncpfs symlink handling bug. 2005-08-19 18:02:56 -07:00
sysctl.c NFSv4: Allow entries in the idmap cache to expire 2006-01-06 14:58:58 -05:00
unlink.c NFS: kzalloc conversion in fs/nfs 2006-03-20 13:44:10 -05:00
write.c [PATCH] mempool: use mempool_create_slab_pool() 2006-03-26 08:57:00 -08:00