VFS: Introduce inode-getting helpers for layered/unioned fs environments (155e35d4) · Commits · 戴 / test

include/linux/dcache.h

+57 −0

Original line number	Diff line number	Diff line
		@@ -464,4 +464,61 @@ static inline unsigned long vfs_pressure_ratio(unsigned long val)
		{
		return mult_frac(val, sysctl_vfs_cache_pressure, 100);
		}

		/**
		* d_inode - Get the actual inode of this dentry
		* @dentry: The dentry to query
		*
		* This is the helper normal filesystems should use to get at their own inodes
		* in their own dentries and ignore the layering superimposed upon them.
		*/
		static inline struct inode d_inode(const struct dentry dentry)
		{
		return dentry->d_inode;
		}

		/**
		* d_inode_rcu - Get the actual inode of this dentry with ACCESS_ONCE()
		* @dentry: The dentry to query
		*
		* This is the helper normal filesystems should use to get at their own inodes
		* in their own dentries and ignore the layering superimposed upon them.
		*/
		static inline struct inode d_inode_rcu(const struct dentry dentry)
		{
		return ACCESS_ONCE(dentry->d_inode);
		}

		/**
		* d_backing_inode - Get upper or lower inode we should be using
		* @upper: The upper layer
		*
		* This is the helper that should be used to get at the inode that will be used
		* if this dentry were to be opened as a file. The inode may be on the upper
		* dentry or it may be on a lower dentry pinned by the upper.
		*
		* Normal filesystems should not use this to access their own inodes.
		*/
		static inline struct inode d_backing_inode(const struct dentry upper)
		{
		struct inode *inode = upper->d_inode;

		return inode;
		}

		/**
		* d_backing_dentry - Get upper or lower dentry we should be using
		* @upper: The upper layer
		*
		* This is the helper that should be used to get the dentry of the inode that
		* will be used if this dentry were opened as a file. It may be the upper
		* dentry or it may be a lower dentry pinned by the upper.
		*
		* Normal filesystems should not use this to access their own dentries.
		*/
		static inline struct dentry d_backing_dentry(struct dentry upper)
		{
		return upper;
		}

		#endif /* __LINUX_DCACHE_H */

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