Sharing inode with different whiteout files for saving
inode and speeding up deleting operation.
Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
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.
v3->v4:
- Disable the feature after link failure.
- Add mount option(whiteout link max) for overlayfs instance.
v4->v5:
- Add a warning when mount option exceeds module parameter.
fs/overlayfs/dir.c | 47 ++++++++++++++++++++++++++++++++++------
fs/overlayfs/overlayfs.h | 10 +++++++--
fs/overlayfs/ovl_entry.h | 5 +++++
fs/overlayfs/readdir.c | 3 ++-
fs/overlayfs/super.c | 27 +++++++++++++++++++++++
fs/overlayfs/util.c | 3 ++-
6 files changed, 84 insertions(+), 11 deletions(-)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 279009dee366..8b7d8854f31f 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -62,35 +62,67 @@ 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;
+ err = 0;
+ if (should_link) {
+ if (ovl_whiteout_linkable(ofs)) {
+ err = ovl_do_link(ofs->whiteout, wdir, whiteout);
+ if (!err)
+ return whiteout;
+ } else if (ofs->whiteout) {
+ dput(whiteout);
+ whiteout = ofs->whiteout;
+ ofs->whiteout = NULL;
+ return whiteout;
+ }
+
+ if (err) {
+ pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%i)\n",
+ ofs->whiteout->d_inode->i_nlink, err);
+ ofs->whiteout_link_max = 0;
+ should_link = false;
+ ovl_cleanup(wdir, ofs->whiteout);
+ dput(ofs->whiteout);
+ ofs->whiteout = NULL;
+ }
+ }
+
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 +747,7 @@ 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 +781,7 @@ 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..3b127c997a6d 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -225,6 +225,12 @@ 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 &&
+ 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 +461,8 @@ 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..c805c35e0594 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -17,6 +17,7 @@ struct ovl_config {
bool nfs_export;
int xino;
bool metacopy;
+ unsigned int whiteout_link_max;
};
struct ovl_sb {
@@ -77,6 +78,10 @@ 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 20f5310d3ee4..bf22fb7792c1 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -1154,7 +1154,8 @@ 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 f57aa348dcd6..af837e2910aa 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);
@@ -358,6 +363,10 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
if (ofs->config.metacopy != ovl_metacopy_def)
seq_printf(m, ",metacopy=%s",
ofs->config.metacopy ? "on" : "off");
+ if (ofs->config.whiteout_link_max != ovl_whiteout_link_max_def)
+ seq_printf(m, ",whiteout_link_max=%u",
+ ofs->config.whiteout_link_max);
+
return 0;
}
@@ -398,6 +407,7 @@ enum {
OPT_XINO_AUTO,
OPT_METACOPY_ON,
OPT_METACOPY_OFF,
+ OPT_WHITEOUT_LINK_MAX,
OPT_ERR,
};
@@ -416,6 +426,7 @@ static const match_table_t ovl_tokens = {
{OPT_XINO_AUTO, "xino=auto"},
{OPT_METACOPY_ON, "metacopy=on"},
{OPT_METACOPY_OFF, "metacopy=off"},
+ {OPT_WHITEOUT_LINK_MAX, "whiteout_link_max=%u"},
{OPT_ERR, NULL}
};
@@ -469,6 +480,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
{
char *p;
int err;
+ int link_max;
bool metacopy_opt = false, redirect_opt = false;
bool nfs_export_opt = false, index_opt = false;
@@ -560,6 +572,16 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
metacopy_opt = true;
break;
+ case OPT_WHITEOUT_LINK_MAX:
+ if (match_int(&args[0], &link_max))
+ return -EINVAL;
+ if (link_max < ovl_whiteout_link_max_def) {
+ config->whiteout_link_max = link_max;
+ pr_warn("mount option whiteout_link_max=%u exceeds module parameter, set it equal to module parameter %u",
+ link_max, ovl_whiteout_link_max_def);
+ }
+ break;
+
default:
pr_err("unrecognized mount option \"%s\" or missing value\n",
p);
@@ -1269,6 +1291,10 @@ static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
pr_warn("NFS export requires \"index=on\", falling back to nfs_export=off.\n");
ofs->config.nfs_export = false;
}
+
+ ofs->whiteout_link_max = min_not_zero(
+ ofs->workdir->d_sb->s_max_links,
+ ofs->config.whiteout_link_max ?: 1);
out:
mnt_drop_write(mnt);
return err;
@@ -1768,6 +1794,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ofs->config.nfs_export = ovl_nfs_export_def;
ofs->config.xino = ovl_xino_def();
ofs->config.metacopy = ovl_metacopy_def;
+ ofs->config.whiteout_link_max = ovl_whiteout_link_max_def;
err = ovl_parse_opt((char *) data, &ofs->config);
if (err)
goto out_err;
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
