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Message-Id: <4d827eae305473e2bf@agluck-desktop.sc.intel.com>
Date: Thu, 17 Mar 2011 14:35:42 -0700
From: Tony Luck <tony.luck@...el.com>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: Xiaotian Feng <xtfeng@...il.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Some fixes for pstore (Was Re: [git pull] mnt_devname queue)
Al,
I haven't got all your suggestions implemented yet - but thought I'd do
a quick direction check to see if I understood your e-mail.
Fixes below:
1) Change from ->get_sb() to ->mount()
2) Use mount_single() instead of mount_nodev()
3) Pulled in ramfs_get_inode() & trimmed to what I need for pstore
4) Drop the ugly pstore_writefile() Just save data using kmalloc() and
provide a pstore_file_read() that uses simple_read_from_buffer().
Still todo:
1) Handle multiple mounts
2) Use simple_pin_fs/mntput to prevent races
3) Move cleanup from unlink to evict_inode
4) Stop it from saving dmesg on a clean "reboot" [!! Not sure when it started doing this !!]
-Tony
---
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 549d245..7d848b1 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -40,9 +40,29 @@
struct pstore_private {
u64 id;
int (*erase)(u64);
+ ssize_t size;
+ char data[];
};
-#define pstore_get_inode ramfs_get_inode
+static int pstore_file_open(struct inode *inode, struct file *file)
+{
+ file->private_data = inode->i_private;
+ return 0;
+}
+
+static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ struct pstore_private *ps = file->private_data;
+
+ return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
+}
+
+static const struct file_operations pstore_file_operations = {
+ .open = pstore_file_open,
+ .read = pstore_file_read,
+ .llseek = default_llseek,
+};
/*
* When a file is unlinked from our file system we call the
@@ -63,6 +83,30 @@ static const struct inode_operations pstore_dir_inode_operations = {
.unlink = pstore_unlink,
};
+static struct inode *pstore_get_inode(struct super_block *sb,
+ const struct inode *dir, int mode, dev_t dev)
+{
+ struct inode *inode = new_inode(sb);
+
+ if (inode) {
+ inode->i_ino = get_next_ino();
+ inode->i_uid = inode->i_gid = 0;
+ inode->i_mode = mode;
+ inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+ switch (mode & S_IFMT) {
+ case S_IFREG:
+ inode->i_fop = &pstore_file_operations;
+ break;
+ case S_IFDIR:
+ inode->i_op = &pstore_dir_inode_operations;
+ inode->i_fop = &simple_dir_operations;
+ inc_nlink(inode);
+ break;
+ }
+ }
+ return inode;
+}
+
static const struct super_operations pstore_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
@@ -70,37 +114,10 @@ static const struct super_operations pstore_ops = {
};
static struct super_block *pstore_sb;
-static struct vfsmount *pstore_mnt;
int pstore_is_mounted(void)
{
- return pstore_mnt != NULL;
-}
-
-/*
- * Set up a file structure as if we had opened this file and
- * write our data to it.
- */
-static int pstore_writefile(struct inode *inode, struct dentry *dentry,
- char *data, size_t size)
-{
- struct file f;
- ssize_t n;
- mm_segment_t old_fs = get_fs();
-
- memset(&f, '0', sizeof f);
- f.f_mapping = inode->i_mapping;
- f.f_path.dentry = dentry;
- f.f_path.mnt = pstore_mnt;
- f.f_pos = 0;
- f.f_op = inode->i_fop;
- set_fs(KERNEL_DS);
- n = do_sync_write(&f, data, size, &f.f_pos);
- set_fs(old_fs);
-
- fsnotify_modify(&f);
-
- return n == size;
+ return pstore_sb != NULL;
}
/*
@@ -123,8 +140,7 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
inode = pstore_get_inode(pstore_sb, root->d_inode, S_IFREG | 0444, 0);
if (!inode)
goto fail;
- inode->i_uid = inode->i_gid = 0;
- private = kmalloc(sizeof *private, GFP_KERNEL);
+ private = kmalloc(sizeof *private + size, GFP_KERNEL);
if (!private)
goto fail_alloc;
private->id = id;
@@ -156,8 +172,8 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
mutex_unlock(&root->d_inode->i_mutex);
- if (!pstore_writefile(inode, dentry, data, size))
- goto fail_write;
+ memcpy(private->data, data, size);
+ inode->i_size = private->size = size;
inode->i_private = private;
@@ -166,15 +182,6 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
return 0;
-fail_write:
- kfree(private);
- inode->i_nlink--;
- mutex_lock(&root->d_inode->i_mutex);
- d_delete(dentry);
- dput(dentry);
- mutex_unlock(&root->d_inode->i_mutex);
- goto fail;
-
fail_lockedalloc:
mutex_unlock(&root->d_inode->i_mutex);
kfree(private);
@@ -225,32 +232,27 @@ fail:
return err;
}
-static int pstore_get_sb(struct file_system_type *fs_type,
- int flags, const char *dev_name, void *data, struct vfsmount *mnt)
+static struct dentry *pstore_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
{
struct dentry *root;
- root = mount_nodev(fs_type, flags, data, pstore_fill_super);
+ root = mount_single(fs_type, flags, data, pstore_fill_super);
if (IS_ERR(root))
- return -ENOMEM;
-
- mnt->mnt_root = root;
- mnt->mnt_sb = root->d_sb;
- pstore_mnt = mnt;
+ return root;
- return 0;
+ return root;
}
static void pstore_kill_sb(struct super_block *sb)
{
kill_litter_super(sb);
pstore_sb = NULL;
- pstore_mnt = NULL;
}
static struct file_system_type pstore_fs_type = {
.name = "pstore",
- .get_sb = pstore_get_sb,
+ .mount = pstore_mount,
.kill_sb = pstore_kill_sb,
};
--
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