André Almeida <[email protected]> writes:
> Implement IOCTL operations for files to set/get file flags. Implement
> the only supported flag by now, that is S_CASEFOLD.
>
> Signed-off-by: André Almeida <[email protected]>
> ---
> include/linux/shmem_fs.h | 4 ++
> mm/shmem.c | 84 +++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 87 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> index 29ee64352807..2c89c5a66508 100644
> --- a/include/linux/shmem_fs.h
> +++ b/include/linux/shmem_fs.h
> @@ -140,4 +140,8 @@ extern int shmem_mfill_zeropage_pte(struct mm_struct
> *dst_mm,
> dst_addr) ({ BUG(); 0; })
> #endif
>
> +#define TMPFS_CASEFOLD_FL 0x40000000 /* Casefolded file */
> +#define TMPFS_USER_FLS TMPFS_CASEFOLD_FL /* Userspace
> supported flags */
> +#define TMPFS_FLS S_CASEFOLD /* Kernel supported flags */
Minor nit: FLS? _FLAGS is short enough :).
> +
> #endif
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 20df81763995..2f2c996d215b 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -258,6 +258,7 @@ static inline void shmem_inode_unacct_blocks(struct inode
> *inode, long pages)
> static const struct super_operations shmem_ops;
> const struct address_space_operations shmem_aops;
> static const struct file_operations shmem_file_operations;
> +static const struct file_operations shmem_dir_operations;
> static const struct inode_operations shmem_inode_operations;
> static const struct inode_operations shmem_dir_inode_operations;
> static const struct inode_operations shmem_special_inode_operations;
> @@ -2347,7 +2348,7 @@ static struct inode *shmem_get_inode(struct super_block
> *sb, const struct inode
> /* Some things misbehave if size == 0 on a directory */
> inode->i_size = 2 * BOGO_DIRENT_SIZE;
> inode->i_op = &shmem_dir_inode_operations;
> - inode->i_fop = &simple_dir_operations;
> + inode->i_fop = &shmem_dir_operations;
> break;
> case S_IFLNK:
> /*
> @@ -2838,6 +2839,76 @@ static long shmem_fallocate(struct file *file, int
> mode, loff_t offset,
> return error;
> }
>
> +static long shmem_ioctl(struct file *file, unsigned int cmd, unsigned long
> arg)
> +{
> + int ret;
> + u32 fsflags = 0, old, new = 0;
> + struct inode *inode = file_inode(file);
> + struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
> +
> + switch (cmd) {
> + case FS_IOC_GETFLAGS:
> + if ((inode->i_flags & S_CASEFOLD) && S_ISDIR(inode->i_mode))
> + fsflags |= TMPFS_CASEFOLD_FL;
> +
> + if (put_user(fsflags, (int __user *)arg))
> + return -EFAULT;
> +
> + return 0;
> +
> + case FS_IOC_SETFLAGS:
> + if (get_user(fsflags, (int __user *)arg))
> + return -EFAULT;
> +
> + old = inode->i_flags;
> +
> + if (fsflags & ~TMPFS_USER_FLS)
> + return -EINVAL;
> +
> + if (fsflags & TMPFS_CASEFOLD_FL) {
> + if (!sbinfo->casefold) {
> + pr_err("tmpfs: casefold disabled at this mount
> point\n");
Minor nit: no point in logging an error here. The user has simply not
enabled casefolding. The error returned below should be enough.
> + return -EOPNOTSUPP;
> + }
> +
> + if (!S_ISDIR(inode->i_mode))
> + return -ENOTDIR;
> +
> + if (!simple_empty(file_dentry(file)))
> + return -ENOTEMPTY;
> +
> + new |= S_CASEFOLD;
> + } else if (old & S_CASEFOLD) {
> + if (!simple_empty(file_dentry(file)))
> + return -ENOTEMPTY;
> + }
> +
> + ret = mnt_want_write_file(file);
> + if (ret)
> + return ret;
> +
> + inode_lock(inode);
> +
> + ret = vfs_ioc_setflags_prepare(inode, old, new);
> + if (ret) {
> + inode_unlock(inode);
> + mnt_drop_write_file(file);
> + return ret;
> + }
> +
> + inode_set_flags(inode, new, TMPFS_FLS);
> +
> + inode_unlock(inode);
> + mnt_drop_write_file(file);
> + return 0;
> +
> + default:
> + return -ENOTTY;
> + }
> +
> + return 0;
> +}
> +
> static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
> {
> struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
> @@ -3916,6 +3987,7 @@ static const struct file_operations
> shmem_file_operations = {
> .splice_read = generic_file_splice_read,
> .splice_write = iter_file_splice_write,
> .fallocate = shmem_fallocate,
> + .unlocked_ioctl = shmem_ioctl,
> #endif
> };
>
> @@ -3928,6 +4000,16 @@ static const struct inode_operations
> shmem_inode_operations = {
> #endif
> };
>
> +static const struct file_operations shmem_dir_operations = {
> + .open = dcache_dir_open,
> + .release = dcache_dir_close,
> + .llseek = dcache_dir_lseek,
> + .read = generic_read_dir,
> + .iterate_shared = dcache_readdir,
> + .fsync = noop_fsync,
> + .unlocked_ioctl = shmem_ioctl,
> +};
> +
> static const struct inode_operations shmem_dir_inode_operations = {
> #ifdef CONFIG_TMPFS
> .create = shmem_create,
--
Gabriel Krisman Bertazi
