115 lines
3.4 KiB
Diff
115 lines
3.4 KiB
Diff
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From 57c8073caecaaaeb087d1bad0de1baa497189181 Mon Sep 17 00:00:00 2001
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From: Andy Whitcroft <apw@canonical.com>
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Date: Thu, 27 Jun 2013 16:39:50 +0200
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Subject: [PATCH 6/9] overlayfs: add statfs support
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Add support for statfs to the overlayfs filesystem. As the upper layer
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is the target of all write operations assume that the space in that
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filesystem is the space in the overlayfs. There will be some inaccuracy as
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overwriting a file will copy it up and consume space we were not expecting,
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but it is better than nothing.
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Use the upper layer dentry and mount from the overlayfs root inode,
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passing the statfs call to that filesystem.
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Signed-off-by: Andy Whitcroft <apw@canonical.com>
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Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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---
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fs/overlayfs/super.c | 40 ++++++++++++++++++++++++++++++++++++++++
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1 file changed, 40 insertions(+)
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diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
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index d209dd9..a9970b5 100644
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--- a/fs/overlayfs/super.c
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+++ b/fs/overlayfs/super.c
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@@ -17,15 +17,19 @@
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#include <linux/module.h>
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#include <linux/cred.h>
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#include <linux/sched.h>
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+#include <linux/statfs.h>
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#include "overlayfs.h"
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MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
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MODULE_DESCRIPTION("Overlay filesystem");
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MODULE_LICENSE("GPL");
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+#define OVERLAYFS_SUPER_MAGIC 0x794c764f
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+
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struct ovl_fs {
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struct vfsmount *upper_mnt;
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struct vfsmount *lower_mnt;
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+ long lower_namelen;
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};
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struct ovl_entry {
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@@ -406,9 +410,36 @@ static int ovl_remount_fs(struct super_block *sb, int *flagsp, char *data)
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return mnt_want_write(ufs->upper_mnt);
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}
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+/**
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+ * ovl_statfs
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+ * @sb: The overlayfs super block
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+ * @buf: The struct kstatfs to fill in with stats
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+ *
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+ * Get the filesystem statistics. As writes always target the upper layer
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+ * filesystem pass the statfs to the same filesystem.
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+ */
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+static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
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+{
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+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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+ struct dentry *root_dentry = dentry->d_sb->s_root;
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+ struct path path;
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+ int err;
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+
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+ ovl_path_upper(root_dentry, &path);
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+
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+ err = vfs_statfs(&path, buf);
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+ if (!err) {
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+ buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen);
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+ buf->f_type = OVERLAYFS_SUPER_MAGIC;
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+ }
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+
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+ return err;
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+}
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+
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static const struct super_operations ovl_super_operations = {
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.put_super = ovl_put_super,
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.remount_fs = ovl_remount_fs,
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+ .statfs = ovl_statfs,
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};
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struct ovl_config {
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@@ -474,6 +505,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
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struct ovl_entry *oe;
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struct ovl_fs *ufs;
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struct ovl_config config;
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+ struct kstatfs statfs;
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int err;
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err = ovl_parse_opt((char *) data, &config);
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@@ -508,6 +540,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
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!S_ISDIR(lowerpath.dentry->d_inode->i_mode))
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goto out_put_lowerpath;
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+ err = vfs_statfs(&lowerpath, &statfs);
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+ if (err) {
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+ pr_err("overlayfs: statfs failed on lowerpath\n");
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+ goto out_put_lowerpath;
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+ }
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+ ufs->lower_namelen = statfs.f_namelen;
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+
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ufs->upper_mnt = clone_private_mount(&upperpath);
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err = PTR_ERR(ufs->upper_mnt);
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if (IS_ERR(ufs->upper_mnt)) {
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@@ -556,6 +595,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
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root_dentry->d_fsdata = oe;
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root_dentry->d_op = &ovl_dentry_operations;
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+ sb->s_magic = OVERLAYFS_SUPER_MAGIC;
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sb->s_op = &ovl_super_operations;
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sb->s_root = root_dentry;
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sb->s_fs_info = ufs;
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--
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1.8.3.2
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