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Message-ID: <20150519055119.GA39478@jaegeuk-mac02.hsd1.ca.comcast.net>
Date: Mon, 18 May 2015 22:51:19 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao2.yu@...sung.com>
Cc: Changman Lee <cm224.lee@...sung.com>,
linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] f2fs: support RENAME_WHITEOUT
Hi Chao,
On Mon, May 18, 2015 at 01:54:22PM +0800, Chao Yu wrote:
> As the description of rename in manual, RENAME_WHITEOUT is a special operation
> that only makes sense for overlay/union type filesystem.
>
> When performing rename with RENAME_WHITEOUT, dst will be replace with src, and
> meanwhile, a 'whiteout' will be create with name of src.
>
> A "whiteout" is designed to be a char device with 0,0 device number, it has
> specially meaning for stackable filesystem. In these filesystems, there are
> multiple layers exist, and only top of these can be modified. So a whiteout
> in top layer is used to hide a corresponding file in lower layer, as well
> removal of whiteout will make the file appear.
>
> Now in overlayfs, when we rename a file which is exist in lower layer, it
> will be copied up to upper if it is not on upper layer yet, and then rename
> it on upper layer, source file will be whiteouted to hide corresponding file
> in lower layer at the same time.
>
> So in upper layer filesystem, implementation of RENAME_WHITEOUT provide a
> atomic operation for stackable filesystem to support rename operation.
>
> There are multiple ways to implement RENAME_WHITEOUT in log of this commit:
> 7dcf5c3e4527 ("xfs: add RENAME_WHITEOUT support") which pointed out by
> Dave Chinner.
>
> For now, we just try to follow the way that xfs/ext4 use.
Could you merge the two patches into one?
And, after finishing xfstests, kernel reports missing inode objects.
Could you check it out?
I didn't take a closer look at it.
>
> Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> ---
> fs/f2fs/namei.c | 140 ++++++++++++++++++++++++++++++++++++--------------------
> 1 file changed, 90 insertions(+), 50 deletions(-)
>
> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> index 16b74da..bed0cb0 100644
> --- a/fs/f2fs/namei.c
> +++ b/fs/f2fs/namei.c
> @@ -510,14 +510,80 @@ out:
> return err;
> }
>
> +static int __f2fs_tmpfile(struct inode *dir, struct dentry *dentry,
> + umode_t mode, struct inode **whiteout)
> +{
> + struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
> + struct inode *inode;
> + int err;
> +
> + inode = f2fs_new_inode(dir, mode);
> + if (IS_ERR(inode))
> + return PTR_ERR(inode);
> +
> + if (whiteout) {
> + init_special_inode(inode, inode->i_mode, WHITEOUT_DEV);
> + inode->i_op = &f2fs_special_inode_operations;
> + } else {
> + inode->i_op = &f2fs_file_inode_operations;
> + inode->i_fop = &f2fs_file_operations;
> + inode->i_mapping->a_ops = &f2fs_dblock_aops;
> + }
> +
> + f2fs_lock_op(sbi);
> + err = acquire_orphan_inode(sbi);
> + if (err)
> + goto out;
> +
> + err = f2fs_do_tmpfile(inode, dir);
> + if (err)
> + goto release_out;
> +
> + /*
> + * add this non-linked tmpfile to orphan list, in this way we could
> + * remove all unused data of tmpfile after abnormal power-off.
> + */
> + add_orphan_inode(sbi, inode->i_ino);
> + f2fs_unlock_op(sbi);
> +
> + alloc_nid_done(sbi, inode->i_ino);
> +
> + if (whiteout) {
> + inode_dec_link_count(inode);
Maybe due to this?
We don't need to decrease its link count?
Thanks,
> + *whiteout = inode;
> + } else {
> + d_tmpfile(dentry, inode);
> + }
> + unlock_new_inode(inode);
> + return 0;
> +
> +release_out:
> + release_orphan_inode(sbi);
> +out:
> + handle_failed_inode(inode);
> + return err;
> +}
> +
> +static int f2fs_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
> +{
> + return __f2fs_tmpfile(dir, dentry, mode, NULL);
> +}
> +
> +static int f2fs_create_whiteout(struct inode *dir, struct inode **whiteout)
> +{
> + return __f2fs_tmpfile(dir, NULL, S_IFCHR | WHITEOUT_MODE, whiteout);
> +}
> +
> static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
> - struct inode *new_dir, struct dentry *new_dentry)
> + struct inode *new_dir, struct dentry *new_dentry,
> + unsigned int flags)
> {
> struct f2fs_sb_info *sbi = F2FS_I_SB(old_dir);
> struct inode *old_inode = d_inode(old_dentry);
> struct inode *new_inode = d_inode(new_dentry);
> + struct inode *whiteout = NULL;
> struct page *old_dir_page;
> - struct page *old_page, *new_page;
> + struct page *old_page, *new_page = NULL;
> struct f2fs_dir_entry *old_dir_entry = NULL;
> struct f2fs_dir_entry *old_entry;
> struct f2fs_dir_entry *new_entry;
> @@ -543,6 +609,12 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
> goto out_old;
> }
>
> + if (flags & RENAME_WHITEOUT) {
> + err = f2fs_create_whiteout(old_dir, &whiteout);
> + if (err)
> + goto out_dir;
> + }
> +
> if (new_inode) {
>
> err = -ENOTEMPTY;
> @@ -611,8 +683,17 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>
> f2fs_delete_entry(old_entry, old_page, old_dir, NULL);
>
> + if (whiteout) {
> + whiteout->i_state |= I_LINKABLE;
> + set_inode_flag(F2FS_I(whiteout), FI_INC_LINK);
> + err = f2fs_add_link(old_dentry, whiteout);
> + if (err)
> + goto put_out_dir;
> + whiteout->i_state &= ~I_LINKABLE;
> + }
> +
> if (old_dir_entry) {
> - if (old_dir != new_dir) {
> + if (old_dir != new_dir && !whiteout) {
> f2fs_set_link(old_inode, old_dir_entry,
> old_dir_page, new_dir);
> update_inode_page(old_inode);
> @@ -633,8 +714,10 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
>
> put_out_dir:
> f2fs_unlock_op(sbi);
> - f2fs_dentry_kunmap(new_dir, new_page);
> - f2fs_put_page(new_page, 0);
> + if (new_page) {
> + f2fs_dentry_kunmap(new_dir, new_page);
> + f2fs_put_page(new_page, 0);
> + }
> out_dir:
> if (old_dir_entry) {
> f2fs_dentry_kunmap(old_inode, old_dir_page);
> @@ -805,7 +888,7 @@ static int f2fs_rename2(struct inode *old_dir, struct dentry *old_dentry,
> struct inode *new_dir, struct dentry *new_dentry,
> unsigned int flags)
> {
> - if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
> + if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
> return -EINVAL;
>
> if (flags & RENAME_EXCHANGE) {
> @@ -816,50 +899,7 @@ static int f2fs_rename2(struct inode *old_dir, struct dentry *old_dentry,
> * VFS has already handled the new dentry existence case,
> * here, we just deal with "RENAME_NOREPLACE" as regular rename.
> */
> - return f2fs_rename(old_dir, old_dentry, new_dir, new_dentry);
> -}
> -
> -static int f2fs_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
> -{
> - struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
> - struct inode *inode;
> - int err;
> -
> - inode = f2fs_new_inode(dir, mode);
> - if (IS_ERR(inode))
> - return PTR_ERR(inode);
> -
> - inode->i_op = &f2fs_file_inode_operations;
> - inode->i_fop = &f2fs_file_operations;
> - inode->i_mapping->a_ops = &f2fs_dblock_aops;
> -
> - f2fs_lock_op(sbi);
> - err = acquire_orphan_inode(sbi);
> - if (err)
> - goto out;
> -
> - err = f2fs_do_tmpfile(inode, dir);
> - if (err)
> - goto release_out;
> -
> - /*
> - * add this non-linked tmpfile to orphan list, in this way we could
> - * remove all unused data of tmpfile after abnormal power-off.
> - */
> - add_orphan_inode(sbi, inode->i_ino);
> - f2fs_unlock_op(sbi);
> -
> - alloc_nid_done(sbi, inode->i_ino);
> -
> - d_tmpfile(dentry, inode);
> - unlock_new_inode(inode);
> - return 0;
> -
> -release_out:
> - release_orphan_inode(sbi);
> -out:
> - handle_failed_inode(inode);
> - return err;
> + return f2fs_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
> }
>
> #ifdef CONFIG_F2FS_FS_ENCRYPTION
> --
> 2.3.3
--
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