Re: [PATCH v3] f2fs: add fast symlink support

[Wanpeng Li]

Ping Jaegeuk,
On Fri, Mar 13, 2015 at 02:33:39PM +0800, Wanpeng Li wrote:
>This patch introduces the improvement fast symlinks to allow storage of
>the target path within inode, thus symlinks with short target paths are
>more accessed quickly. It will fall back to using the original slow
>symlink if the target path exceeds the available inode space.
>
>Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx>
>---
>v2 -> v3:
> * handle fast symlink in remove_inode_page
>v1 -> v2:
> * set max size of fast symlink according to inline_xattr flag
>
> fs/f2fs/f2fs.h          | 15 ++++++++++++++
> fs/f2fs/file.c          |  2 ++
> fs/f2fs/inode.c         |  9 +++++++--
> fs/f2fs/namei.c         | 53 +++++++++++++++++++++++++++++++++++++++++++++----
> fs/f2fs/node.c          |  5 +++--
> include/linux/f2fs_fs.h |  2 ++
> 6 files changed, 78 insertions(+), 8 deletions(-)
>
>diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>index 511d6cd..3012ea0 100644
>--- a/fs/f2fs/f2fs.h
>+++ b/fs/f2fs/f2fs.h
>@@ -1226,6 +1226,7 @@ enum {
> 	FI_VOLATILE_FILE,	/* indicate volatile file */
> 	FI_DROP_CACHE,		/* drop dirty page cache */
> 	FI_DATA_EXIST,		/* indicate data exists */
>+	FI_FAST_SYMLINK,        /* indicate fast symlink */
> };
> 
> static inline void set_inode_flag(struct f2fs_inode_info *fi, int flag)
>@@ -1262,6 +1263,8 @@ static inline void get_inline_info(struct f2fs_inode_info *fi,
> 		set_inode_flag(fi, FI_INLINE_DENTRY);
> 	if (ri->i_inline & F2FS_DATA_EXIST)
> 		set_inode_flag(fi, FI_DATA_EXIST);
>+	if (ri->i_inline & F2FS_FAST_SYMLINK)
>+		set_inode_flag(fi, FI_FAST_SYMLINK);
> }
> 
> static inline void set_raw_inline(struct f2fs_inode_info *fi,
>@@ -1277,6 +1280,8 @@ static inline void set_raw_inline(struct f2fs_inode_info *fi,
> 		ri->i_inline |= F2FS_INLINE_DENTRY;
> 	if (is_inode_flag_set(fi, FI_DATA_EXIST))
> 		ri->i_inline |= F2FS_DATA_EXIST;
>+	if (is_inode_flag_set(fi, FI_FAST_SYMLINK))
>+		ri->i_inline |= F2FS_FAST_SYMLINK;
> }
> 
> static inline int f2fs_has_inline_xattr(struct inode *inode)
>@@ -1370,6 +1375,15 @@ static inline void f2fs_stop_checkpoint(struct f2fs_sb_info *sbi)
> 	sbi->sb->s_flags |= MS_RDONLY;
> }
> 
>+/*
>+ * Test whether an inode is a fast symlink.
>+ */
>+static inline int f2fs_inode_is_fast_symlink(struct inode *inode)
>+{
>+	return (S_ISLNK(inode->i_mode) &&
>+			is_inode_flag_set(F2FS_I(inode), FI_FAST_SYMLINK));
>+}
>+
> #define get_inode_mode(i) \
> 	((is_inode_flag_set(F2FS_I(i), FI_ACL_MODE)) ? \
> 	 (F2FS_I(i)->i_acl_mode) : ((i)->i_mode))
>@@ -1746,6 +1760,7 @@ extern const struct address_space_operations f2fs_node_aops;
> extern const struct address_space_operations f2fs_meta_aops;
> extern const struct inode_operations f2fs_dir_inode_operations;
> extern const struct inode_operations f2fs_symlink_inode_operations;
>+extern const struct inode_operations f2fs_fast_symlink_inode_operations;
> extern const struct inode_operations f2fs_special_inode_operations;
> extern struct kmem_cache *inode_entry_slab;
> 
>diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>index f1341c7..05a3d4f 100644
>--- a/fs/f2fs/file.c
>+++ b/fs/f2fs/file.c
>@@ -546,6 +546,8 @@ void f2fs_truncate(struct inode *inode)
> 	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
> 				S_ISLNK(inode->i_mode)))
> 		return;
>+	if (f2fs_inode_is_fast_symlink(inode))
>+		return;
> 
> 	trace_f2fs_truncate(inode);
> 
>diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
>index b508744..ec9ad22 100644
>--- a/fs/f2fs/inode.c
>+++ b/fs/f2fs/inode.c
>@@ -13,6 +13,7 @@
> #include <linux/buffer_head.h>
> #include <linux/writeback.h>
> #include <linux/bitops.h>
>+#include <linux/namei.h>
> 
> #include "f2fs.h"
> #include "node.h"
>@@ -188,8 +189,12 @@ make_now:
> 		inode->i_mapping->a_ops = &f2fs_dblock_aops;
> 		mapping_set_gfp_mask(inode->i_mapping, GFP_F2FS_HIGH_ZERO);
> 	} else if (S_ISLNK(inode->i_mode)) {
>-		inode->i_op = &f2fs_symlink_inode_operations;
>-		inode->i_mapping->a_ops = &f2fs_dblock_aops;
>+		if (f2fs_inode_is_fast_symlink(inode))
>+			inode->i_op = &f2fs_fast_symlink_inode_operations;
>+		else {
>+			inode->i_op = &f2fs_symlink_inode_operations;
>+			inode->i_mapping->a_ops = &f2fs_dblock_aops;
>+		}
> 	} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
> 			S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
> 		inode->i_op = &f2fs_special_inode_operations;
>diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
>index 1e2ae21..0619909 100644
>--- a/fs/f2fs/namei.c
>+++ b/fs/f2fs/namei.c
>@@ -14,6 +14,7 @@
> #include <linux/sched.h>
> #include <linux/ctype.h>
> #include <linux/dcache.h>
>+#include <linux/namei.h>
> 
> #include "f2fs.h"
> #include "node.h"
>@@ -247,6 +248,21 @@ fail:
> 	return err;
> }
> 
>+static void *f2fs_follow_link(struct dentry *dentry, struct nameidata *nd)
>+{
>+	struct page *node_page;
>+
>+	node_page = get_node_page(F2FS_I_SB(dentry->d_inode),
>+				dentry->d_inode->i_ino);
>+	if (IS_ERR(node_page)) {
>+		nd_set_link(nd, NULL);
>+		return NULL;
>+	}
>+	nd_set_link(nd, (char *)(F2FS_INODE(node_page)->i_addr));
>+	f2fs_put_page(node_page, 1);
>+	return NULL;
>+}
>+
> static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
> 					const char *symname)
> {
>@@ -261,16 +277,31 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
> 	if (IS_ERR(inode))
> 		return PTR_ERR(inode);
> 
>-	inode->i_op = &f2fs_symlink_inode_operations;
>-	inode->i_mapping->a_ops = &f2fs_dblock_aops;
>-
> 	f2fs_lock_op(sbi);
> 	err = f2fs_add_link(dentry, inode);
> 	if (err)
> 		goto out;
> 	f2fs_unlock_op(sbi);
> 
>-	err = page_symlink(inode, symname, symlen);
>+
>+	if (symlen > MAX_FAST_SYMLINK_SIZE) {
>+		/* slow symlink */
>+		inode->i_op = &f2fs_symlink_inode_operations;
>+		inode->i_mapping->a_ops = &f2fs_dblock_aops;
>+		err = page_symlink(inode, symname, symlen);
>+	} else {
>+		/* fast symlink */
>+		struct page *node_page;
>+
>+		inode->i_op = &f2fs_fast_symlink_inode_operations;
>+		node_page = get_node_page(sbi, inode->i_ino);
>+		memcpy((char *)&F2FS_INODE(node_page)->i_addr, symname, symlen);
>+		set_page_dirty(node_page);
>+		f2fs_put_page(node_page, 1);
>+		inode->i_size = symlen-1;
>+		set_inode_flag(F2FS_I(inode), FI_FAST_SYMLINK);
>+		mark_inode_dirty(inode);
>+	}
> 	alloc_nid_done(sbi, inode->i_ino);
> 
> 	d_instantiate(dentry, inode);
>@@ -743,6 +774,20 @@ const struct inode_operations f2fs_symlink_inode_operations = {
> #endif
> };
> 
>+const struct inode_operations f2fs_fast_symlink_inode_operations = {
>+	.readlink       = generic_readlink,
>+	.follow_link    = f2fs_follow_link,
>+	.put_link       = page_put_link,
>+	.getattr	= f2fs_getattr,
>+	.setattr	= f2fs_setattr,
>+#ifdef CONFIG_F2FS_FS_XATTR
>+	.setxattr	= generic_setxattr,
>+	.getxattr	= generic_getxattr,
>+	.listxattr	= f2fs_listxattr,
>+	.removexattr	= generic_removexattr,
>+#endif
>+};
>+
> const struct inode_operations f2fs_special_inode_operations = {
> 	.getattr	= f2fs_getattr,
> 	.setattr        = f2fs_setattr,
>diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>index 35a9117..efe28a2b 100644
>--- a/fs/f2fs/node.c
>+++ b/fs/f2fs/node.c
>@@ -908,8 +908,9 @@ void remove_inode_page(struct inode *inode)
> 	}
> 
> 	/* remove potential inline_data blocks */
>-	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
>-				S_ISLNK(inode->i_mode))
>+	if ((S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
>+				S_ISLNK(inode->i_mode)) &&
>+				!f2fs_inode_is_fast_symlink(inode))
> 		truncate_data_blocks_range(&dn, 1);
> 
> 	/* 0 is possible, after f2fs_new_inode() has failed */
>diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
>index 502f28c..834880c 100644
>--- a/include/linux/f2fs_fs.h
>+++ b/include/linux/f2fs_fs.h
>@@ -178,9 +178,11 @@ struct f2fs_extent {
> #define F2FS_INLINE_DATA	0x02	/* file inline data flag */
> #define F2FS_INLINE_DENTRY	0x04	/* file inline dentry flag */
> #define F2FS_DATA_EXIST		0x08	/* file inline data exist flag */
>+#define F2FS_FAST_SYMLINK	0x10    /* file fast symlink flag */
> 
> #define MAX_INLINE_DATA		(sizeof(__le32) * (DEF_ADDRS_PER_INODE - \
> 						F2FS_INLINE_XATTR_ADDRS - 1))
>+#define MAX_FAST_SYMLINK_SIZE (MAX_INLINE_DATA + 1)
> 
> struct f2fs_inode {
> 	__le16 i_mode;			/* file mode */
>-- 
>1.9.1
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