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    Subject[patch 01/33] fs: no games with DCACHE_UNHASHED
    (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
    @@ -307,18 +307,6 @@ 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().
    */
    @@ -329,7 +317,6 @@ static char *sockfs_dname(struct dentry
    }

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

    @@ -378,12 +365,6 @@ 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
    @@ -33,24 +33,11 @@ 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
    @@ -119,9 +106,6 @@ int anon_inode_getfd(const char *name, c
    */
    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;



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