diff options
| author | Mateusz Guzik <mjguzik@gmail.com> | 2024-11-20 12:20:34 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-12-22 11:29:50 +0100 |
| commit | ea382199071931d19aac5f688b543e07360e2b64 (patch) | |
| tree | 375c9ad796a10c2e2abd39b3a766196f354a050b /include | |
| parent | 135ec43eb29c68ed26e2d10f221d43f7d9139a8f (diff) | |
vfs: support caching symlink lengths in inodes
When utilized it dodges strlen() in vfs_readlink(), giving about 1.5%
speed up when issuing readlink on /initrd.img on ext4.
Filesystems opt in by calling inode_set_cached_link() when creating an
inode.
The size is stored in a new union utilizing the same space as i_devices,
thus avoiding growing the struct or taking up any more space.
Churn-wise the current readlink_copy() helper is patched to accept the
size instead of calculating it.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20241120112037.822078-2-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/fs.h | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 7e29433c5ecc..2cc98de5af43 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -626,6 +626,7 @@ is_uncached_acl(struct posix_acl *acl) #define IOP_XATTR 0x0008 #define IOP_DEFAULT_READLINK 0x0010 #define IOP_MGTIME 0x0020 +#define IOP_CACHED_LINK 0x0040 /* * Keep mostly read-only and often accessed (especially for @@ -723,7 +724,10 @@ struct inode { }; struct file_lock_context *i_flctx; struct address_space i_data; - struct list_head i_devices; + union { + struct list_head i_devices; + int i_linklen; + }; union { struct pipe_inode_info *i_pipe; struct cdev *i_cdev; @@ -749,6 +753,13 @@ struct inode { void *i_private; /* fs or device private pointer */ } __randomize_layout; +static inline void inode_set_cached_link(struct inode *inode, char *link, int linklen) +{ + inode->i_link = link; + inode->i_linklen = linklen; + inode->i_opflags |= IOP_CACHED_LINK; +} + /* * Get bit address from inode->i_state to use with wait_var_event() * infrastructre. @@ -3351,7 +3362,7 @@ extern const struct file_operations generic_ro_fops; #define special_file(m) (S_ISCHR(m)||S_ISBLK(m)||S_ISFIFO(m)||S_ISSOCK(m)) -extern int readlink_copy(char __user *, int, const char *); +extern int readlink_copy(char __user *, int, const char *, int); extern int page_readlink(struct dentry *, char __user *, int); extern const char *page_get_link(struct dentry *, struct inode *, struct delayed_call *); |