[GFS2] Clean up/speed up readdir

This removes the extra filldir callback which gfs2 was using to
enclose an attempt at readahead for inodes during readdir. The
code was too complicated and also hurts performance badly in the
case that the getdents64/readdir call isn't being followed by
stat() and it wasn't even getting it right all the time when it
was.

As a result, on my test box an "ls" of a directory containing 250000
files fell from about 7mins (freshly mounted, so nothing cached) to
between about 15 to 25 seconds. When the directory content was cached,
the time taken fell from about 3mins to about 4 or 5 seconds.

Interestingly in the cached case, running "ls -l" once reduced the time
taken for subsequent runs of "ls" to about 6 secs even without this
patch. Now it turns out that there was a special case of glocks being
used for prefetching the metadata, but because of the timeouts for these
locks (set to 10 secs) the metadata was being timed out before it was
being used and this the prefetch code was constantly trying to prefetch
the same data over and over.

Calling "ls -l" meant that the inodes were brought into memory and once
the inodes are cached, the glocks are not disposed of until the inodes
are pushed out of the cache, thus extending the lifetime of the glocks,
and thus bringing down the time for subsequent runs of "ls"
considerably.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 1 insertions, 51 deletions

diff --git a/fs/gfs2/ops_file.c b/fs/gfs2/ops_file.c
index faa07e4b97d0..c996aa739a05 100644
--- a/fs/gfs2/ops_file.c
+++ b/fs/gfs2/ops_file.c
@@ -43,15 +43,6 @@
 #include "util.h"
 #include "eaops.h"
 
-/* For regular, non-NFS */
-struct filldir_reg {
-	struct gfs2_sbd *fdr_sbd;
-	int fdr_prefetch;
-
-	filldir_t fdr_filldir;
-	void *fdr_opaque;
-};
-
 /*
  * Most fields left uninitialised to catch anybody who tries to
  * use them. f_flags set to prevent file_accessed() from touching
@@ -128,41 +119,6 @@ static loff_t gfs2_llseek(struct file *file, loff_t offset, int origin)
 }
 
 /**
- * filldir_func - Report a directory entry to the caller of gfs2_dir_read()
- * @opaque: opaque data used by the function
- * @name: the name of the directory entry
- * @length: the length of the name
- * @offset: the entry's offset in the directory
- * @inum: the inode number the entry points to
- * @type: the type of inode the entry points to
- *
- * Returns: 0 on success, 1 if buffer full
- */
-
-static int filldir_func(void *opaque, const char *name, unsigned int length,
-			u64 offset, struct gfs2_inum_host *inum,
-			unsigned int type)
-{
-	struct filldir_reg *fdr = (struct filldir_reg *)opaque;
-	struct gfs2_sbd *sdp = fdr->fdr_sbd;
-	int error;
-
-	error = fdr->fdr_filldir(fdr->fdr_opaque, name, length, offset,
-				 inum->no_addr, type);
-	if (error)
-		return 1;
-
-	if (fdr->fdr_prefetch && !(length == 1 && *name == '.')) {
-		gfs2_glock_prefetch_num(sdp, inum->no_addr, &gfs2_inode_glops,
-				       LM_ST_SHARED, LM_FLAG_TRY | LM_FLAG_ANY);
-		gfs2_glock_prefetch_num(sdp, inum->no_addr, &gfs2_iopen_glops,
-				       LM_ST_SHARED, LM_FLAG_TRY);
-	}
-
-	return 0;
-}
-
-/**
  * gfs2_readdir - Read directory entries from a directory
  * @file: The directory to read from
  * @dirent: Buffer for dirents
@@ -175,16 +131,10 @@ static int gfs2_readdir(struct file *file, void *dirent, filldir_t filldir)
 {
 	struct inode *dir = file->f_mapping->host;
 	struct gfs2_inode *dip = GFS2_I(dir);
-	struct filldir_reg fdr;
 	struct gfs2_holder d_gh;
 	u64 offset = file->f_pos;
 	int error;
 
-	fdr.fdr_sbd = GFS2_SB(dir);
-	fdr.fdr_prefetch = 1;
-	fdr.fdr_filldir = filldir;
-	fdr.fdr_opaque = dirent;
-
 	gfs2_holder_init(dip->i_gl, LM_ST_SHARED, GL_ATIME, &d_gh);
 	error = gfs2_glock_nq_atime(&d_gh);
 	if (error) {
@@ -192,7 +142,7 @@ static int gfs2_readdir(struct file *file, void *dirent, filldir_t filldir)
 		return error;
 	}
 
-	error = gfs2_dir_read(dir, &offset, &fdr, filldir_func);
+	error = gfs2_dir_read(dir, &offset, dirent, filldir);
 
 	gfs2_glock_dq_uninit(&d_gh);