From: NeilBrown Subject: Make selection of 'readdir-plus' adapt to usage patterns. Patch-mainline: not yet References: bnc#678123 While the use of READDIRPLUS is significantly more efficient than READDIR followed by many GETATTR calls, it is still less efficient than just READDIR if the attributes are not required. We can get a hint as to whether the application requires attr information by looking at whether any ->getattr calls are made between ->readdir calls. If there are any, then getting the attributes seems to be worth while. This patch tracks whether there have been recent getattr calls on children of a directory and uses that information to selectively disable READDIRPLUS on that directory. The first 'readdir' call is always served using READDIRPLUS. Subsequent calls only use READDIRPLUS if there was a getattr on a child in the mean time. The locking of ->d_parent access needs to be reviewed. As the bit is simply a hint, it isn't critical that it is set on the "correct" parent if a rename is happening, but it is critical that the 'set' doesn't set a bit in something that isn't even an inode any more. Acked-by: NeilBrown Signed-off-by: Neil Brown --- fs/nfs/dir.c | 3 +++ fs/nfs/inode.c | 9 +++++++++ include/linux/nfs_fs.h | 4 ++++ 3 files changed, 16 insertions(+) --- linux-2.6.37-openSUSE-11.4.orig/fs/nfs/dir.c +++ linux-2.6.37-openSUSE-11.4/fs/nfs/dir.c @@ -802,6 +802,9 @@ static int nfs_readdir(struct file *filp desc->dir_cookie = &nfs_file_open_context(filp)->dir_cookie; desc->decode = NFS_PROTO(inode)->decode_dirent; desc->plus = NFS_USE_READDIRPLUS(inode); + if (filp->f_pos > 0 && !test_bit(NFS_INO_SEEN_GETATTR, &NFS_I(inode)->flags)) + desc->plus = 0; + clear_bit(NFS_INO_SEEN_GETATTR, &NFS_I(inode)->flags); nfs_block_sillyrename(dentry); res = nfs_revalidate_mapping(inode, filp->f_mapping); --- linux-2.6.37-openSUSE-11.4.orig/fs/nfs/inode.c +++ linux-2.6.37-openSUSE-11.4/fs/nfs/inode.c @@ -500,6 +500,15 @@ int nfs_getattr(struct vfsmount *mnt, st struct inode *inode = dentry->d_inode; int need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME; int err; + struct dentry *p; + struct inode *pi; + + rcu_read_lock(); + p = dentry->d_parent; + pi = rcu_dereference(p)->d_inode; + if (pi && !test_bit(NFS_INO_SEEN_GETATTR, &NFS_I(pi)->flags)) + set_bit(NFS_INO_SEEN_GETATTR, &NFS_I(pi)->flags); + rcu_read_unlock(); /* Flush out writes to the server in order to update c/mtime. */ if (S_ISREG(inode->i_mode)) { --- linux-2.6.37-openSUSE-11.4.orig/include/linux/nfs_fs.h +++ linux-2.6.37-openSUSE-11.4/include/linux/nfs_fs.h @@ -220,6 +220,10 @@ struct nfs_inode { #define NFS_INO_FSCACHE (5) /* inode can be cached by FS-Cache */ #define NFS_INO_FSCACHE_LOCK (6) /* FS-Cache cookie management lock */ #define NFS_INO_COMMIT (7) /* inode is committing unstable writes */ +#define NFS_INO_SEEN_GETATTR (8) /* flag to track if app is calling + * getattr in a directory during + * readdir + */ static inline struct nfs_inode *NFS_I(const struct inode *inode) {