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