Track negative entries v3

Track negative dentries by recording the generation number of the parent
directory in d_fsdata. The generation number for the parent directory is
recorded in the inode_info, which increments every time the lock on the
directory is dropped.

If the generation number of the parent directory and the negative dentry
matches, there is no need to perform the revalidate, else a revalidate
is forced. This improves performance in situations where nodes look for
the same non-existent file multiple times.

Thanks Mark for explaining the DLM sequence.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.de>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c
index b4957c7d9fe2262a203a3efb3573eda9ed3d2638..edaded48e7e9f083ac7c67e72a9f031123f7844a 100644 (file)
--- a/fs/ocfs2/dcache.c
+++ b/fs/ocfs2/dcache.c
@@ -40,6 +40,14 @@
 #include "inode.h"
 #include "super.h"
 
+void ocfs2_dentry_attach_gen(struct dentry *dentry)
+{
+       unsigned long gen =
+               OCFS2_I(dentry->d_parent->d_inode)->ip_dir_lock_gen;
+       BUG_ON(dentry->d_inode);
+       dentry->d_fsdata = (void *)gen;
+}
+
 
 static int ocfs2_dentry_revalidate(struct dentry *dentry,
                                   struct nameidata *nd)
@@ -51,11 +59,20 @@ static int ocfs2_dentry_revalidate(struct dentry *dentry,
        mlog_entry("(0x%p, '%.*s')\n", dentry,
                   dentry->d_name.len, dentry->d_name.name);
 
-       /* Never trust a negative dentry - force a new lookup. */
+       /* For a negative dentry -
+        * check the generation number of the parent and compare with the
+        * one stored in the inode.
+        */
        if (inode == NULL) {
-               mlog(0, "negative dentry: %.*s\n", dentry->d_name.len,
-                    dentry->d_name.name);
-               goto bail;
+               unsigned long gen = (unsigned long) dentry->d_fsdata;
+               unsigned long pgen =
+                       OCFS2_I(dentry->d_parent->d_inode)->ip_dir_lock_gen;
+               mlog(0, "negative dentry: %.*s parent gen: %lu "
+                       "dentry gen: %lu\n",
+                       dentry->d_name.len, dentry->d_name.name, pgen, gen);
+               if (gen != pgen)
+                       goto bail;
+               goto valid;
        }
 
        BUG_ON(!osb);
@@ -96,6 +113,7 @@ static int ocfs2_dentry_revalidate(struct dentry *dentry,
                goto bail;
        }
 
+valid:
        ret = 1;
 
 bail:
@@ -227,6 +245,12 @@ int ocfs2_dentry_attach_lock(struct dentry *dentry,
        if (!inode)
                return 0;
 
+       if (!dentry->d_inode && dentry->d_fsdata) {
+               /* Converting a negative dentry to positive
+                  Clear dentry->d_fsdata */
+               dentry->d_fsdata = dl = NULL;
+       }
+
        if (dl) {
                mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
                                " \"%.*s\": old parent: %llu, new: %llu\n",
@@ -452,6 +476,7 @@ static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode)
 
 out:
        iput(inode);
+       ocfs2_dentry_attach_gen(dentry);
 }
 
 /*

diff --git a/fs/ocfs2/dcache.h b/fs/ocfs2/dcache.h
index f5dd1789acf1b4527373217ce7c6b0374695eb17..b79eff709958f806ce92f937cbfd7730e4d36a29 100644 (file)
--- a/fs/ocfs2/dcache.h
+++ b/fs/ocfs2/dcache.h
@@ -64,5 +64,6 @@ void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target,
                       struct inode *old_dir, struct inode *new_dir);
 
 extern spinlock_t dentry_attach_lock;
+void ocfs2_dentry_attach_gen(struct dentry *dentry);
 
 #endif /* OCFS2_DCACHE_H */

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 5e02a893f46ea5e1e4fa5a5c0313b5d7356e1526..e8d94d722ecb8b6dc7aad1ceaa749c99d51cf8a6 100644 (file)
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -3635,10 +3635,18 @@ static int ocfs2_data_convert_worker(struct ocfs2_lock_res *lockres,
 {
        struct inode *inode;
        struct address_space *mapping;
+       struct ocfs2_inode_info *oi;
 
                inode = ocfs2_lock_res_inode(lockres);
        mapping = inode->i_mapping;
 
+       if (S_ISDIR(inode->i_mode)) {
+               oi = OCFS2_I(inode);
+               oi->ip_dir_lock_gen++;
+               mlog(0, "generation: %u\n", oi->ip_dir_lock_gen);
+               goto out;
+       }
+
        if (!S_ISREG(inode->i_mode))
                goto out;
 

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index eece3e05d9d0124d04b81c940c1289f876e700bb..f935fd6600dd1e07e7625161671758795ce477b0 100644 (file)
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -335,6 +335,7 @@ void ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
                    else
                            inode->i_fop = &ocfs2_dops_no_plocks;
                    i_size_write(inode, le64_to_cpu(fe->i_size));
+                   OCFS2_I(inode)->ip_dir_lock_gen = 1;
                    break;
            case S_IFLNK:
                    if (ocfs2_inode_is_fast_symlink(inode))

diff --git a/fs/ocfs2/inode.h b/fs/ocfs2/inode.h
index 0bc477a3aeb8d375c37aa8a7444be258b1f3d755..1c508b149b3ac1bd4325fd33a9aae6bdb70e024a 100644 (file)
--- a/fs/ocfs2/inode.h
+++ b/fs/ocfs2/inode.h
@@ -67,6 +67,7 @@ struct ocfs2_inode_info
        /* Only valid if the inode is the dir. */
        u32                             ip_last_used_slot;
        u64                             ip_last_used_group;
+       u32                             ip_dir_lock_gen;
 
        struct ocfs2_alloc_reservation  ip_la_data_resv;
 };

diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index a00dda2e4f16698e5c7d8e0946ba1f09506651c6..e7bde21149aee4f4e1dfed501069358927a064d7 100644 (file)
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -171,7 +171,8 @@ bail_add:
                        ret = ERR_PTR(status);
                        goto bail_unlock;
                }
-       }
+       } else
+               ocfs2_dentry_attach_gen(dentry);
 
 bail_unlock:
        /* Don't drop the cluster lock until *after* the d_add --