I'll try to come up with something for ncpfs.
Trivial lock replacement will open deadlock possibility when someone reads to
page which is also mmaped from the same filesystem (like grep likes to do). BKL
with its automated release on sleep helped (or papered over) a lot here.
Petr
Arnd Bergmann a...@arndb.de wrote:
On Thursday 16 September 2010, Anton Altaparmakov wrote:
On 16 Sep 2010, at 16:04, Jan Kara wrote:
On Thu 16-09-10 16:32:59, Arnd Bergmann wrote:
The big kernel lock is gone from almost all code in linux-next, this is
the status of what I think will happen to the remaining users:
...
fs/ncpfs:
Should be fixable if Petr still cares about it. Otherwise suggest
moving to drivers/staging if there are no users left.
I think some people still use this...
Yes, indeed. Netware is still alive (unfortunately!) and ncpfs is used in a
lot of
Universities here in the UK at least (we use it about a thousand
workstations and
servers here at Cambridge University!).
Ok, that means at least when someone gets around to fix it, there will be
people that can test the patches.
If you know someone who would like to help on this, it would be nice to try
out the patch below, unless someone can come up with a better solution.
My naïve understanding of the code tells me that simply using the super block
lock there may work. In fact it makes locking stricter, so if it still works
with that patch, there are probably no subtle regressions.
The patch applies to current linux-next of my bkl/vfs series.
Arnd
---
ncpfs: replace BKL with lock_super
This mindlessly changes every instance of lock_kernel in ncpfs to
lock_super. I haven't tested this, it may work or may break horribly.
Please test with CONFIG_LOCKDEP enabled.
Signed-off-by: Arnd Bergmann a...@arndb.de
diff --git a/fs/ncpfs/dir.c b/fs/ncpfs/dir.c
index 9578cbe..303338d 100644
--- a/fs/ncpfs/dir.c
+++ b/fs/ncpfs/dir.c
@@ -19,7 +19,6 @@
#include linux/mm.h
#include asm/uaccess.h
#include asm/byteorder.h
-#include linux/smp_lock.h
#include linux/ncp_fs.h
@@ -339,9 +338,10 @@ static int
ncp_lookup_validate(struct dentry * dentry, struct nameidata *nd)
{
int res;
- lock_kernel();
+ struct super_block *sb = dentry-d_inode-i_sb;
+ lock_super(sb);
res = __ncp_lookup_validate(dentry);
- unlock_kernel();
+ unlock_super(sb);
return res;
}
@@ -404,6 +404,7 @@ static int ncp_readdir(struct file *filp, void *dirent,
filldir_t filldir)
{
struct dentry *dentry = filp-f_path.dentry;
struct inode *inode = dentry-d_inode;
+ struct super_block *sb = inode-i_sb;
struct page *page = NULL;
struct ncp_server *server = NCP_SERVER(inode);
union ncp_dir_cache *cache = NULL;
@@ -411,7 +412,7 @@ static int ncp_readdir(struct file *filp, void *dirent,
filldir_t filldir)
int result, mtime_valid = 0;
time_t mtime = 0;
- lock_kernel();
+ lock_super(sb);
ctl.page = NULL;
ctl.cache = NULL;
@@ -546,7 +547,7 @@ finished:
page_cache_release(ctl.page);
}
out:
- unlock_kernel();
+ unlock_super(sb);
return result;
}
@@ -794,12 +795,13 @@ out:
static struct dentry *ncp_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
struct ncp_server *server = NCP_SERVER(dir);
+ struct super_block *sb = dir-i_sb;
struct inode *inode = NULL;
struct ncp_entry_info finfo;
int error, res, len;
__u8 __name[NCP_MAXPATHLEN + 1];
- lock_kernel();
+ lock_super(sb);
error = -EIO;
if (!ncp_conn_valid(server))
goto finished;
@@ -846,7 +848,7 @@ add_entry:
finished:
PPRINTK(ncp_lookup: result=%d\n, error);
- unlock_kernel();
+ unlock_super(sb);
return ERR_PTR(error);
}
@@ -880,6 +882,7 @@ int ncp_create_new(struct inode *dir, struct dentry
*dentry, int mode,
{
struct ncp_server *server = NCP_SERVER(dir);
struct ncp_entry_info finfo;
+ struct super_block *sb = dir-i_sb;
int error, result, len;
int opmode;
__u8 __name[NCP_MAXPATHLEN + 1];
@@ -888,7 +891,7 @@ int ncp_create_new(struct inode *dir, struct dentry
*dentry, int mode,
dentry-d_parent-d_name.name, dentry-d_name.name, mode);
error = -EIO;
- lock_kernel();
+ lock_super(sb);
if (!ncp_conn_valid(server))
goto out;
@@ -935,7 +938,7 @@ int ncp_create_new(struct inode *dir, struct dentry
*dentry, int mode,
error = ncp_instantiate(dir, dentry, finfo);
out:
- unlock_kernel();
+ unlock_super(sb);
return error;
}
@@ -949,6 +952,7 @@ static int ncp_mkdir(struct inode *dir, struct dentry
*dentry, int mode)
{
struct ncp_entry_info finfo;
struct ncp_server *server = NCP_SERVER(dir);
+ struct super_block *sb = dir-i_sb;
int error, len;
__u8
