[patch 2/6] fs: no games with DCACHE_UNHASHED

npiggin
2009-10-15T06:05:24Z

[-- Attachment #1: unhashed-d_delete.patch --]
[-- Type: text/plain, Size: 4438 bytes --]

(this is in -mm)

Filesystems outside the regular namespace do not have to clear DCACHE_UNHASHED
in order to have a working /proc/$pid/fd/XXX. Nothing in proc prevents the
fd link from being used if its dentry is not in the hash.

Also, it does not get put into the dcache hash if DCACHE_UNHASHED is clear;
that depends on the filesystem calling d_add or d_rehash.

So delete the misleading comments and needless code.

Acked-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Nick Piggin <npiggin@suse.de>
---
fs/anon_inodes.c | 16 ----------------
fs/pipe.c | 18 ------------------
net/socket.c | 19 -------------------
3 files changed, 53 deletions(-)

Index: linux-2.6/fs/pipe.c
===================================================================
--- linux-2.6.orig/fs/pipe.c
+++ linux-2.6/fs/pipe.c
@@ -887,17 +887,6 @@ void free_pipe_info(struct inode *inode)
}

static struct vfsmount *pipe_mnt __read_mostly;
-static int pipefs_delete_dentry(struct dentry *dentry)
-{
- /*
- * At creation time, we pretended this dentry was hashed
- * (by clearing DCACHE_UNHASHED bit in d_flags)
- * At delete time, we restore the truth : not hashed.
- * (so that dput() can proceed correctly)
- */
- dentry->d_flags |= DCACHE_UNHASHED;
- return 0;
-}

/*
* pipefs_dname() is called from d_path().
@@ -909,7 +898,6 @@ static char *pipefs_dname(struct dentry
}

static const struct dentry_operations pipefs_dentry_operations = {
- .d_delete = pipefs_delete_dentry,
.d_dname = pipefs_dname,
};

@@ -969,12 +957,6 @@ struct file *create_write_pipe(int flags
goto err_inode;

dentry->d_op = &pipefs_dentry_operations;
- /*
- * We dont want to publish this dentry into global dentry hash table.
- * We pretend dentry is already hashed, by unsetting DCACHE_UNHASHED
- * This permits a working /proc/$pid/fd/XXX on pipes
- */
- dentry->d_flags &= ~DCACHE_UNHASHED;
d_instantiate(dentry, inode);

err = -ENFILE;
Index: linux-2.6/net/socket.c
===================================================================
--- linux-2.6.orig/net/socket.c
+++ linux-2.6/net/socket.c
@@ -306,18 +306,6 @@ static struct file_system_type sock_fs_t
.kill_sb = kill_anon_super,
};

-static int sockfs_delete_dentry(struct dentry *dentry)
-{
- /*
- * At creation time, we pretended this dentry was hashed
- * (by clearing DCACHE_UNHASHED bit in d_flags)
- * At delete time, we restore the truth : not hashed.
- * (so that dput() can proceed correctly)
- */
- dentry->d_flags |= DCACHE_UNHASHED;
- return 0;
-}
-
/*
* sockfs_dname() is called from d_path().
*/
@@ -328,7 +316,6 @@ static char *sockfs_dname(struct dentry
}

static const struct dentry_operations sockfs_dentry_operations = {
- .d_delete = sockfs_delete_dentry,
.d_dname = sockfs_dname,
};

@@ -377,12 +364,6 @@ static int sock_attach_fd(struct socket
return -ENOMEM;

dentry->d_op = &sockfs_dentry_operations;
- /*
- * We dont want to push this dentry into global dentry hash table.
- * We pretend dentry is already hashed, by unsetting DCACHE_UNHASHED
- * This permits a working /proc/$pid/fd/XXX on sockets
- */
- dentry->d_flags &= ~DCACHE_UNHASHED;
d_instantiate(dentry, SOCK_INODE(sock));

sock->file = file;
Index: linux-2.6/fs/anon_inodes.c
===================================================================
--- linux-2.6.orig/fs/anon_inodes.c
+++ linux-2.6/fs/anon_inodes.c
@@ -35,24 +35,11 @@ static int anon_inodefs_get_sb(struct fi
mnt);
}

-static int anon_inodefs_delete_dentry(struct dentry *dentry)
-{
- /*
- * We faked vfs to believe the dentry was hashed when we created it.
- * Now we restore the flag so that dput() will work correctly.
- */
- dentry->d_flags |= DCACHE_UNHASHED;
- return 1;
-}
-
static struct file_system_type anon_inode_fs_type = {
.name = "anon_inodefs",
.get_sb = anon_inodefs_get_sb,
.kill_sb = kill_anon_super,
};
-static const struct dentry_operations anon_inodefs_dentry_operations = {
- .d_delete = anon_inodefs_delete_dentry,
-};

/*
* nop .set_page_dirty method so that people can use .page_mkwrite on
@@ -117,9 +104,6 @@ struct file *anon_inode_getfile(const ch
*/
atomic_inc(&anon_inode_inode->i_count);

- dentry->d_op = &anon_inodefs_dentry_operations;
- /* Do not publish this dentry inside the global dentry hash table */
- dentry->d_flags &= ~DCACHE_UNHASHED;
d_instantiate(dentry, anon_inode_inode);

error = -ENFILE;