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Date: Tue, 23 Mar 2021 16:59:40 -0300
From: André Almeida <andrealmeid@...labora.com>
To: Hugh Dickins <hughd@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Alexander Viro <viro@...iv.linux.org.uk>
Cc: krisman@...labora.com, smcv@...labora.com, kernel@...labora.com,
linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, Daniel Rosenberg <drosen@...gle.com>,
André Almeida <andrealmeid@...labora.com>
Subject: [RFC PATCH 3/4] mm: shmem: Add IOCTL support for tmpfs
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 <andrealmeid@...labora.com>
---
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 */
+
#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");
+ 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,
--
2.31.0
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