[PATCH V9 18/33] fs: create file_readable() and file_writable() functions

From: Dave Kleikamp
Date: Wed Oct 16 2013 - 10:10:56 EST


Create functions to simplify if file_ops contain either a read
or aio_read op, or likewise write or aio_write. We will be adding
read_iter and write_iter and don't need to be complicating the code
in multiple places.

Signed-off-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
---
drivers/mtd/nand/nandsim.c | 4 ++--
drivers/usb/gadget/storage_common.c | 4 ++--
fs/read_write.c | 14 +++++++-------
include/linux/fs.h | 10 ++++++++++
4 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/drivers/mtd/nand/nandsim.c b/drivers/mtd/nand/nandsim.c
index bdc1d15..414f522 100644
--- a/drivers/mtd/nand/nandsim.c
+++ b/drivers/mtd/nand/nandsim.c
@@ -575,12 +575,12 @@ static int alloc_device(struct nandsim *ns)
cfile = filp_open(cache_file, O_CREAT | O_RDWR | O_LARGEFILE, 0600);
if (IS_ERR(cfile))
return PTR_ERR(cfile);
- if (!cfile->f_op || (!cfile->f_op->read && !cfile->f_op->aio_read)) {
+ if (!file_readable(cfile)) {
NS_ERR("alloc_device: cache file not readable\n");
err = -EINVAL;
goto err_close;
}
- if (!cfile->f_op->write && !cfile->f_op->aio_write) {
+ if (!file_writable(cfile)) {
NS_ERR("alloc_device: cache file not writeable\n");
err = -EINVAL;
goto err_close;
diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c
index 08a1a32..cd1431d 100644
--- a/drivers/usb/gadget/storage_common.c
+++ b/drivers/usb/gadget/storage_common.c
@@ -450,11 +450,11 @@ static int fsg_lun_open(struct fsg_lun *curlun, const char *filename)
* If we can't read the file, it's no good.
* If we can't write the file, use it read-only.
*/
- if (!(filp->f_op->read || filp->f_op->aio_read)) {
+ if (!file_readable(filp)) {
LINFO(curlun, "file not readable: %s\n", filename);
goto out;
}
- if (!(filp->f_op->write || filp->f_op->aio_write))
+ if (!file_writable(filp))
ro = 1;

size = i_size_read(inode->i_mapping->host);
diff --git a/fs/read_write.c b/fs/read_write.c
index e3cd280..f92f74f 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -384,7 +384,7 @@ ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)

if (!(file->f_mode & FMODE_READ))
return -EBADF;
- if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
+ if (!file_readable(file))
return -EINVAL;
if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
return -EFAULT;
@@ -433,7 +433,7 @@ ssize_t __kernel_write(struct file *file, const char *buf, size_t count, loff_t
const char __user *p;
ssize_t ret;

- if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
+ if (!file_writable(file))
return -EINVAL;

old_fs = get_fs();
@@ -460,7 +460,7 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_

if (!(file->f_mode & FMODE_WRITE))
return -EBADF;
- if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
+ if (!file_writable(file))
return -EINVAL;
if (unlikely(!access_ok(VERIFY_READ, buf, count)))
return -EFAULT;
@@ -778,7 +778,7 @@ ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
{
if (!(file->f_mode & FMODE_READ))
return -EBADF;
- if (!file->f_op || (!file->f_op->aio_read && !file->f_op->read))
+ if (!file_readable(file))
return -EINVAL;

return do_readv_writev(READ, file, vec, vlen, pos);
@@ -791,7 +791,7 @@ ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
{
if (!(file->f_mode & FMODE_WRITE))
return -EBADF;
- if (!file->f_op || (!file->f_op->aio_write && !file->f_op->write))
+ if (!file_writable(file))
return -EINVAL;

return do_readv_writev(WRITE, file, vec, vlen, pos);
@@ -965,7 +965,7 @@ static size_t compat_readv(struct file *file,
goto out;

ret = -EINVAL;
- if (!file->f_op || (!file->f_op->aio_read && !file->f_op->read))
+ if (!file_readable(file))
goto out;

ret = compat_do_readv_writev(READ, file, vec, vlen, pos);
@@ -1032,7 +1032,7 @@ static size_t compat_writev(struct file *file,
goto out;

ret = -EINVAL;
- if (!file->f_op || (!file->f_op->aio_write && !file->f_op->write))
+ if (!file_writable(file))
goto out;

ret = compat_do_readv_writev(WRITE, file, vec, vlen, pos);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ab43916..5ffec5e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1650,6 +1650,16 @@ struct file_operations {
int (*show_fdinfo)(struct seq_file *m, struct file *f);
};

+static inline int file_readable(struct file *filp)
+{
+ return filp && (filp->f_op->read || filp->f_op->aio_read);
+}
+
+static inline int file_writable(struct file *filp)
+{
+ return filp && (filp->f_op->write || filp->f_op->aio_write);
+}
+
struct inode_operations {
struct dentry * (*lookup) (struct inode *,struct dentry *, unsigned int);
void * (*follow_link) (struct dentry *, struct nameidata *);
--
1.8.4

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