Commit df1a085a authored by David Howells's avatar David Howells Committed by Al Viro
Browse files

VFS: Add a fallthrough flag for marking virtual dentries 



Add a DCACHE_FALLTHRU flag to indicate that, in a layered filesystem, this is
a virtual dentry that covers another one in a lower layer that should be used
instead.  This may be recorded on medium if directory integration is stored
there.

The flag can be set with d_set_fallthru() and tested with d_is_fallthru().

Original-author: Valerie Aurora <vaurora@redhat.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent e7f7d225

fs/dcache.c

+18 −1
Original line number Diff line number Diff line
@@ -1659,6 +1659,22 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) 
}

EXPORT_SYMBOL(d_set_d_op);





/*

 * d_set_fallthru - Mark a dentry as falling through to a lower layer

 * @dentry - The dentry to mark

 *

 * Mark a dentry as falling through to the lower layer (as set with

 * d_pin_lower()).  This flag may be recorded on the medium.

 */

void d_set_fallthru(struct dentry *dentry)

{

	spin_lock(&dentry->d_lock);

	dentry->d_flags |= DCACHE_FALLTHRU;

	spin_unlock(&dentry->d_lock);

}

EXPORT_SYMBOL(d_set_fallthru);



static unsigned d_flags_for_inode(struct inode *inode)

{

	unsigned add_flags = DCACHE_FILE_TYPE;
@@ -1691,7 +1707,8 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode) 
	unsigned add_flags = d_flags_for_inode(inode);



	spin_lock(&dentry->d_lock);

	__d_set_type(dentry, add_flags);

	dentry->d_flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);

	dentry->d_flags |= add_flags;

	if (inode)

		hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);

	dentry->d_inode = inode;

include/linux/dcache.h

+9 −0
Original line number Diff line number Diff line
@@ -223,6 +223,7 @@ struct dentry_operations { 
#define DCACHE_FILE_TYPE		0x00500000 /* Other file type (or fallthru to such) */



#define DCACHE_MAY_FREE			0x00800000

#define DCACHE_FALLTHRU			0x01000000 /* Fall through to lower layer */



extern seqlock_t rename_lock;
@@ -470,6 +471,14 @@ static inline bool d_is_positive(const struct dentry *dentry) 
	return !d_is_negative(dentry);

}



extern void d_set_fallthru(struct dentry *dentry);



static inline bool d_is_fallthru(const struct dentry *dentry)

{

	return dentry->d_flags & DCACHE_FALLTHRU;

}





extern int sysctl_vfs_cache_pressure;



static inline unsigned long vfs_pressure_ratio(unsigned long val)

CRA Git | Maintained and supported by SUSTech CRA and CCSE