From 5e98d492406818e6a94c0ba54c61f59d40cefa4a Mon Sep 17 00:00:00 2001 From: Goldwyn Rodrigues Date: Mon, 28 Jun 2010 10:04:32 -0500 Subject: 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 Signed-off-by: Joel Becker --- fs/ocfs2/dcache.c | 33 +++++++++++++++++++++++++++++---- 1 file changed, 29 insertions(+), 4 deletions(-) (limited to 'fs/ocfs2/dcache.c') diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c index b4957c7d9fe2..edaded48e7e9 100644 --- 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); } /* -- cgit