Sharing inode with different whiteout files for saving
inode and speeding up deleting operation.
Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxxxx>
---
v1->v2:
- Address Amir's comments in v1
v2->v3:
- Address Amir's comments in v2
- Rebase on Amir's "Overlayfs use index dir as work dir" patch set
- Keep at most one whiteout tmpfile in work dir
fs/overlayfs/dir.c | 35 ++++++++++++++++++++++++++++-------
fs/overlayfs/overlayfs.h | 9 +++++++--
fs/overlayfs/ovl_entry.h | 4 ++++
fs/overlayfs/readdir.c | 3 ++-
fs/overlayfs/super.c | 9 +++++++++
fs/overlayfs/util.c | 3 ++-
6 files changed, 52 insertions(+), 11 deletions(-)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 279009dee366..dbe5e54dcb16 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -62,35 +62,55 @@ struct dentry *ovl_lookup_temp(struct dentry *workdir)
}
/* caller holds i_mutex on workdir */
-static struct dentry *ovl_whiteout(struct dentry *workdir)
+static struct dentry *ovl_whiteout(struct ovl_fs *ofs, struct dentry *workdir)
{
int err;
+ bool retried = false;
+ bool should_link = (ofs->whiteout_link_max > 1);
struct dentry *whiteout;
struct inode *wdir = workdir->d_inode;
+retry:
whiteout = ovl_lookup_temp(workdir);
if (IS_ERR(whiteout))
return whiteout;
+ if (should_link && ofs->whiteout) {
+ err = ovl_do_link(ofs->whiteout, wdir, whiteout);
+ if (err || !ovl_whiteout_linkable(ofs)) {
+ ovl_cleanup(wdir, ofs->whiteout);
+ dput(ofs->whiteout);
+ ofs->whiteout = NULL;
+ }
+
+ if (!err)
+ return whiteout;
+ }
+
err = ovl_do_whiteout(wdir, whiteout);
if (err) {
dput(whiteout);
- whiteout = ERR_PTR(err);
+ return ERR_PTR(err);
}
- return whiteout;
+ if (!should_link || retried)
+ return whiteout;
+
+ ofs->whiteout = whiteout;
+ retried = true;
+ goto retry;
}
/* Caller must hold i_mutex on both workdir and dir */
-int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
- struct dentry *dentry)
+int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct dentry *workdir,
+ struct inode *dir, struct dentry *dentry)
{
struct inode *wdir = workdir->d_inode;
struct dentry *whiteout;
int err;
int flags = 0;
- whiteout = ovl_whiteout(workdir);
+ whiteout = ovl_whiteout(ofs, workdir);
err = PTR_ERR(whiteout);
if (IS_ERR(whiteout))
return err;
@@ -715,6 +735,7 @@ static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper)
static int ovl_remove_and_whiteout(struct dentry *dentry,
struct list_head *list)
{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
struct dentry *workdir = ovl_workdir(dentry);
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
struct dentry *upper;
@@ -748,7 +769,7 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
goto out_dput_upper;
}
- err = ovl_cleanup_and_whiteout(workdir, d_inode(upperdir), upper);
+ err = ovl_cleanup_and_whiteout(ofs, workdir, d_inode(upperdir), upper);
if (err)
goto out_d_drop;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index e00b1ff6dea9..3d7e0e342dae 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -225,6 +225,11 @@ static inline bool ovl_open_flags_need_copy_up(int flags)
return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
}
+static inline bool ovl_whiteout_linkable(struct ovl_fs *ofs)
+{
+ return ofs->whiteout->d_inode->i_nlink <= ofs->whiteout_link_max;
+}
+
/* util.c */
int ovl_want_write(struct dentry *dentry);
void ovl_drop_write(struct dentry *dentry);
@@ -455,8 +460,8 @@ static inline void ovl_copyflags(struct inode *from, struct inode *to)
/* dir.c */
extern const struct inode_operations ovl_dir_inode_operations;
-int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
- struct dentry *dentry);
+int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct dentry *workdir,
+ struct inode *dir, struct dentry *dentry);
struct ovl_cattr {
dev_t rdev;
umode_t mode;
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 5762d802fe01..de5f230b6e6b 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -77,6 +77,10 @@ struct ovl_fs {
int xino_mode;
/* For allocation of non-persistent inode numbers */
atomic_long_t last_ino;
+ /* Whiteout dentry cache */
+ struct dentry *whiteout;
+ /* Whiteout max link count */
+ unsigned int whiteout_link_max;
};
static inline struct ovl_fs *OVL_FS(struct super_block *sb)
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index d6b601caf122..eb4683e58cff 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -1147,7 +1147,8 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
* Whiteout orphan index to block future open by
* handle after overlay nlink dropped to zero.
*/
- err = ovl_cleanup_and_whiteout(indexdir, dir, index);
+ err = ovl_cleanup_and_whiteout(ofs, indexdir, dir,
+ index);
} else {
/* Cleanup orphan index entries */
err = ovl_cleanup(dir, index);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index b91b23a0366c..b6f2393ec111 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -26,6 +26,10 @@ struct ovl_dir_cache;
#define OVL_MAX_STACK 500
+static unsigned int ovl_whiteout_link_max_def = 60000;
+module_param_named(whiteout_link_max, ovl_whiteout_link_max_def, uint, 0644);
+MODULE_PARM_DESC(whiteout_link_max, "Maximum count of whiteout file link");
+
static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR);
module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644);
MODULE_PARM_DESC(redirect_dir,
@@ -219,6 +223,7 @@ static void ovl_free_fs(struct ovl_fs *ofs)
iput(ofs->upperdir_trap);
dput(ofs->indexdir);
dput(ofs->workdir);
+ dput(ofs->whiteout);
if (ofs->workdir_locked)
ovl_inuse_unlock(ofs->workbasedir);
dput(ofs->workbasedir);
@@ -1762,6 +1767,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
if (!ofs->workdir)
sb->s_flags |= SB_RDONLY;
+ else
+ ofs->whiteout_link_max = min_not_zero(
+ ofs->workdir->d_sb->s_max_links,
+ ovl_whiteout_link_max_def ?: 1);
sb->s_stack_depth = ofs->upper_mnt->mnt_sb->s_stack_depth;
sb->s_time_gran = ofs->upper_mnt->mnt_sb->s_time_gran;
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 36b60788ee47..18df65ee81a8 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -669,6 +669,7 @@ bool ovl_need_index(struct dentry *dentry)
/* Caller must hold OVL_I(inode)->lock */
static void ovl_cleanup_index(struct dentry *dentry)
{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
struct inode *dir = indexdir->d_inode;
struct dentry *lowerdentry = ovl_dentry_lower(dentry);
@@ -707,7 +708,7 @@ static void ovl_cleanup_index(struct dentry *dentry)
index = NULL;
} else if (ovl_index_all(dentry->d_sb)) {
/* Whiteout orphan index to block future open by handle */
- err = ovl_cleanup_and_whiteout(indexdir, dir, index);
+ err = ovl_cleanup_and_whiteout(ofs, indexdir, dir, index);
} else {
/* Cleanup orphan index entries */
err = ovl_cleanup(dir, index);
--
2.20.1
