Commit 2f28cc35 authored by Andrew Morton's avatar Andrew Morton Committed by Christoph Hellwig

[PATCH] tmpfs: shmem_file_sendfile

Patch from Hugh Dickins

Added shmem_file_sendfile to allow sendfile from tmpfs.  Checked
do_shmem_file_read and shmem_file_read against filemap equivalents
to add in any recent fixes (-EINVAL when count < 0 was missing).
parent 1956960b
......@@ -1239,6 +1239,7 @@ extern int sb_min_blocksize(struct super_block *, int);
extern int generic_file_mmap(struct file *, struct vm_area_struct *);
extern int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
extern int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
extern ssize_t generic_file_read(struct file *, char *, size_t, loff_t *);
extern ssize_t generic_file_write(struct file *, const char *, size_t, loff_t *);
extern ssize_t generic_file_aio_read(struct kiocb *, char *, size_t, loff_t);
......
......@@ -916,7 +916,7 @@ generic_file_read(struct file *filp, char *buf, size_t count, loff_t *ppos)
return ret;
}
static int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
{
ssize_t written;
unsigned long count = desc->count;
......
......@@ -1136,19 +1136,18 @@ shmem_file_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
goto release;
}
static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc)
static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
{
struct inode *inode = filp->f_dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
unsigned long index, offset;
int nr = 1;
index = *ppos >> PAGE_CACHE_SHIFT;
offset = *ppos & ~PAGE_CACHE_MASK;
while (nr && desc->count) {
for (;;) {
struct page *page;
unsigned long end_index, nr;
unsigned long end_index, nr, ret;
end_index = inode->i_size >> PAGE_CACHE_SHIFT;
if (index > end_index)
......@@ -1181,6 +1180,10 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
}
nr -= offset;
/* If users can be writing to this page using arbitrary
* virtual addresses, take care about potential aliasing
* before reading the page on the kernel side.
*/
if (!list_empty(&mapping->i_mmap_shared) &&
page != ZERO_PAGE(0))
flush_dcache_page(page);
......@@ -1195,12 +1198,14 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
* "pos" here (the actor routine has to update the user buffer
* pointers and the remaining count).
*/
nr = file_read_actor(desc, page, offset, nr);
offset += nr;
ret = actor(desc, page, offset, nr);
offset += ret;
index += offset >> PAGE_CACHE_SHIFT;
offset &= ~PAGE_CACHE_MASK;
page_cache_release(page);
if (ret != nr || !desc->count)
break;
}
*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
......@@ -1209,27 +1214,43 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
static ssize_t shmem_file_read(struct file *filp, char *buf, size_t count, loff_t *ppos)
{
ssize_t retval;
read_descriptor_t desc;
retval = -EFAULT;
if (access_ok(VERIFY_WRITE, buf, count)) {
retval = 0;
if ((ssize_t) count < 0)
return -EINVAL;
if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;
if (!count)
return 0;
if (count) {
desc.written = 0;
desc.count = count;
desc.buf = buf;
desc.error = 0;
do_shmem_file_read(filp, ppos, &desc, file_read_actor);
if (desc.written)
return desc.written;
return desc.error;
}
static ssize_t shmem_file_sendfile(struct file *out_file,
struct file *in_file, loff_t *ppos, size_t count)
{
read_descriptor_t desc;
if (!count)
return 0;
desc.written = 0;
desc.count = count;
desc.buf = buf;
desc.buf = (char *)out_file;
desc.error = 0;
do_shmem_file_read(filp, ppos, &desc);
retval = desc.written;
if (!retval)
retval = desc.error;
}
}
return retval;
do_shmem_file_read(in_file, ppos, &desc, file_send_actor);
if (desc.written)
return desc.written;
return desc.error;
}
static int shmem_statfs(struct super_block *sb, struct statfs *buf)
......@@ -1649,6 +1670,7 @@ static struct file_operations shmem_file_operations = {
.read = shmem_file_read,
.write = shmem_file_write,
.fsync = simple_sync_file,
.sendfile = shmem_file_sendfile,
#endif
};
......
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