Bug #43049: backport ext3

mbcache provides absolutely no value for Lustre xattrs (because
they are unique and cannot be shared between files) and as we can
see it has a noticable overhead in some cases. In the past there
was a CONFIG_MBCACHE option that would allow it to be disabled,
but this was removed in newer kernels, so we will need to patch
ldiskfs to fix this.

<https://bugzilla.kernel.org/show_bug.cgi?id=107301>

--- a/fs/ext3/ext3.h
+++ b/fs/ext3/ext3.h
@@ -340,6 +340,7 @@ struct ext3_inode_info {
  * Mount flags
  */
 #define EXT3_MOUNT_CHECK		0x00001	/* Do mount-time checks */
+#define EXT3_MOUNT_NO_MBCACHE		0x00002 /* Disable mbcache */
 /* EXT3_MOUNT_OLDALLOC was there */
 #define EXT3_MOUNT_GRPID		0x00004	/* Create files with directory's group */
 #define EXT3_MOUNT_DEBUG		0x00008	/* Some debugging messages */
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -814,6 +814,7 @@ enum {
 	Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_jqfmt_vfsv1, Opt_quota,
 	Opt_noquota, Opt_ignore, Opt_barrier, Opt_nobarrier, Opt_err,
 	Opt_resize, Opt_usrquota, Opt_grpquota
+	,Opt_no_mbcache
 };
 
 static const match_table_t tokens = {
@@ -871,6 +872,7 @@ static const match_table_t tokens = {
 	{Opt_nobarrier, "nobarrier"},
 	{Opt_resize, "resize"},
 	{Opt_err, NULL},
+	{Opt_no_mbcache, "no_mbcache"},
 };
 
 static ext3_fsblk_t get_sb_block(void **data, struct super_block *sb)
@@ -1275,6 +1277,9 @@ static inst parse_options {
 			ext3_msg(sb, KERN_WARNING,
 				"warning: ignoring deprecated bh option");
 			break;
+		case Opt_no_mbcache:
+			set_opt(sbi->s_mount_opt, EXT3_MOUNT_NO_MBCACHE);
+			break;
 		default:
 			ext3_msg(sb, KERN_ERR,
 				"error: unrecognized mount option \"%s\" "
--- a/fs/ext3/xattr.c
+++ b/fs/ext3/xattr.c
@@ -88,7 +88,7 @@
 # define ea_bdebug(f...)
 #endif
 
-static void ext3_xattr_cache_insert(struct buffer_head *);
+static void ext3_xattr_cache_insert(struct inode *, struct buffer_head *);
 static struct buffer_head *ext3_xattr_cache_find(struct inode *,
 						 struct ext3_xattr_header *,
 						 struct mb_cache_entry **);
@@ -235,7 +234,7 @@ bad_block:
 		error = -EIO;
 		goto cleanup;
 	}
-	ext3_xattr_cache_insert(bh);
+	ext3_xattr_cache_insert(inode, bh);
 	entry = BFIRST(bh);
 	error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 	if (error == -EIO)
@@ -379,7 +377,7 @@ ext3_xattr_block_list(struct dentry *den
 		error = -EIO;
 		goto cleanup;
 	}
-	ext3_xattr_cache_insert(bh);
+	ext3_xattr_cache_insert(inode, bh);
 	error = ext3_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
 
 cleanup:
@@ -476,7 +474,8 @@ ext3_xattr_release_block(handle_t *handl
 	struct mb_cache_entry *ce = NULL;
 	int error = 0;
 
-	ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
+	if (!test_opt(inode->i_sb, NO_MBCACHE))
+		ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
 	error = ext3_journal_get_write_access(handle, bh);
 	if (error)
 		 goto out;
@@ -687,8 +686,9 @@ ext3_xattr_block_set(handle_t *handle, s
 	if (i->value && i->value_len > sb->s_blocksize)
 		return -ENOSPC;
 	if (s->base) {
-		ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
-					bs->bh->b_blocknr);
+		if (!test_opt(inode->i_sb, NO_MBCACHE))
+			ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
+						bs->bh->b_blocknr);
 		error = ext3_journal_get_write_access(handle, bs->bh);
 		if (error)
 			goto cleanup;
@@ -705,7 +705,7 @@ ext3_xattr_block_set(handle_t *handle, s
 				if (!IS_LAST_ENTRY(s->first))
 					ext3_xattr_rehash(header(s->base),
 							  s->here);
-				ext3_xattr_cache_insert(bs->bh);
+				ext3_xattr_cache_insert(inode, bs->bh);
 			}
 			unlock_buffer(bs->bh);
 			if (error == -EIO)
@@ -787,7 +787,8 @@ inserted:
 				if (error)
 					goto cleanup_dquot;
 			}
-			mb_cache_entry_release(ce);
+			if (ce)
+				mb_cache_entry_release(ce);
 			ce = NULL;
 		} else if (bs->bh && s->base == bs->bh->b_data) {
 			/* We were modifying this block in-place. */
@@ -828,7 +828,7 @@ getblk_failed:
 			memcpy(new_bh->b_data, s->base, new_bh->b_size);
 			set_buffer_uptodate(new_bh);
 			unlock_buffer(new_bh);
-			ext3_xattr_cache_insert(new_bh);
+			ext3_xattr_cache_insert(inode, new_bh);
 			error = ext3_journal_dirty_metadata(handle, new_bh);
 			if (error)
 				goto cleanup;
@@ -1131,12 +1132,16 @@ ext3_xattr_put_super(struct super_block
  * Returns 0, or a negative error number on failure.
  */
 static void
-ext3_xattr_cache_insert(struct buffer_head *bh)
+ext3_xattr_cache_insert(struct inode *inode, struct buffer_head *bh)
 {
+	struct super_block *sb = inode->i_sb;
 	__u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
 	struct mb_cache_entry *ce;
 	int error;
 
+	if (test_opt(sb, NO_MBCACHE))
+		return;
+
 	ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
 	if (!ce) {
 		ea_bdebug(bh, "out of memory");
@@ -1210,6 +1216,8 @@ ext3_xattr_cache_find(struct inode *inod
 	__u32 hash = le32_to_cpu(header->h_hash);
 	struct mb_cache_entry *ce;
 
+	if (test_opt(inode->i_sb, NO_MBCACHE))
+		return NULL;
 	if (!header->h_hash)
 		return NULL;  /* never share */
 	ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);