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VFS: Put a small type field into struct dentry::d_flags

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Put a type field into struct dentry::d_flags to indicate if the dentry is one
of the following types that relate particularly to pathwalk:

	Miss (negative dentry)
	Directory
	"Automount" directory (defective - no i_op->lookup())
	Symlink
	Other (regular, socket, fifo, device)

The type field is set to one of the first five types on a dentry by calls to
__d_instantiate() and d_obtain_alias() from information in the inode (if one is
given).

The type is cleared by dentry_unlink_inode() when it reconstitutes an existing
dentry as a negative dentry.

Accessors provided are:

	d_set_type(dentry, type)
	d_is_directory(dentry)
	d_is_autodir(dentry)
	d_is_symlink(dentry)
	d_is_file(dentry)
	d_is_negative(dentry)
	d_is_positive(dentry)

A bunch of checks in pathname resolution switched to those.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Howells 2013-09-12 19:22:53 +01:00 • committed by Al Viro
parent afabada957
commit b18825a7c8
3 changed files with 158 additions and 82 deletions
Download patch file Download diff file Expand all files Collapse all files

42
fs/dcache.c
View file

@ -343,6 +343,7 @@ static void dentry_unlink_inode(struct dentry * dentry)
__releases(dentry->d_inode->i_lock)
{
struct inode *inode = dentry->d_inode;
__d_clear_type(dentry);
dentry->d_inode = NULL;
hlist_del_init(&dentry->d_alias);
dentry_rcuwalk_barrier(dentry);
@ -1648,14 +1649,42 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
}
EXPORT_SYMBOL(d_set_d_op);
static unsigned d_flags_for_inode(struct inode *inode)
{
unsigned add_flags = DCACHE_FILE_TYPE;
if (!inode)
return DCACHE_MISS_TYPE;
if (S_ISDIR(inode->i_mode)) {
add_flags = DCACHE_DIRECTORY_TYPE;
if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) {
if (unlikely(!inode->i_op->lookup))
add_flags = DCACHE_AUTODIR_TYPE;
else
inode->i_opflags |= IOP_LOOKUP;
}
} else if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
if (unlikely(inode->i_op->follow_link))
add_flags = DCACHE_SYMLINK_TYPE;
else
inode->i_opflags |= IOP_NOFOLLOW;
}
if (unlikely(IS_AUTOMOUNT(inode)))
add_flags |= DCACHE_NEED_AUTOMOUNT;
return add_flags;
}
static void __d_instantiate(struct dentry *dentry, struct inode *inode)
{
unsigned add_flags = d_flags_for_inode(inode);
spin_lock(&dentry->d_lock);
if (inode) {
if (unlikely(IS_AUTOMOUNT(inode)))
dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
dentry->d_flags &= ~DCACHE_ENTRY_TYPE;
dentry->d_flags |= add_flags;
if (inode)
hlist_add_head(&dentry->d_alias, &inode->i_dentry);
}
dentry->d_inode = inode;
dentry_rcuwalk_barrier(dentry);
spin_unlock(&dentry->d_lock);
@ -1860,6 +1889,7 @@ struct dentry *d_obtain_alias(struct inode *inode)
static const struct qstr anonstring = QSTR_INIT("/", 1);
struct dentry *tmp;
struct dentry *res;
unsigned add_flags;
if (!inode)
return ERR_PTR(-ESTALE);
@ -1885,9 +1915,11 @@ struct dentry *d_obtain_alias(struct inode *inode)
}
/* attach a disconnected dentry */
add_flags = d_flags_for_inode(inode) | DCACHE_DISCONNECTED;
spin_lock(&tmp->d_lock);
tmp->d_inode = inode;
tmp->d_flags |= DCACHE_DISCONNECTED;
tmp->d_flags |= add_flags;
hlist_add_head(&tmp->d_alias, &inode->i_dentry);
hlist_bl_lock(&tmp->d_sb->s_anon);
hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);