summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
Diffstat
-rw-r--r--include/linux/fs.h1
-rw-r--r--include/linux/uio.h2
-rw-r--r--mm/filemap.c202
-rw-r--r--mm/shmem.c77
4 files changed, 138 insertions, 144 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2261ac8..2a5b174 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2390,7 +2390,6 @@ extern int generic_file_mmap(struct file *, struct vm_area_struct *);
extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
extern int generic_file_remap_pages(struct vm_area_struct *, unsigned long addr,
unsigned long size, pgoff_t pgoff);
-extern int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk);
extern ssize_t generic_file_aio_read(struct kiocb *, const struct iovec *, unsigned long, loff_t);
extern ssize_t __generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long,
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 347d70c..199bcc3 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -67,6 +67,8 @@ size_t iov_iter_copy_from_user(struct page *page,
void iov_iter_advance(struct iov_iter *i, size_t bytes);
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
size_t iov_iter_single_seg_count(const struct iov_iter *i);
+size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
+ struct iov_iter *i);
static inline void iov_iter_init(struct iov_iter *i,
const struct iovec *iov, unsigned long nr_segs,
diff --git a/mm/filemap.c b/mm/filemap.c
index bfb7a97..a16eb2c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1085,11 +1085,90 @@ static void shrink_readahead_size_eio(struct file *filp,
ra->ra_pages /= 4;
}
+size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
+ struct iov_iter *i)
+{
+ size_t skip, copy, left, wanted;
+ const struct iovec *iov;
+ char __user *buf;
+ void *kaddr, *from;
+
+ if (unlikely(bytes > i->count))
+ bytes = i->count;
+
+ if (unlikely(!bytes))
+ return 0;
+
+ wanted = bytes;
+ iov = i->iov;
+ skip = i->iov_offset;
+ buf = iov->iov_base + skip;
+ copy = min(bytes, iov->iov_len - skip);
+
+ if (!fault_in_pages_writeable(buf, copy)) {
+ kaddr = kmap_atomic(page);
+ from = kaddr + offset;
+
+ /* first chunk, usually the only one */
+ left = __copy_to_user_inatomic(buf, from, copy);
+ copy -= left;
+ skip += copy;
+ from += copy;
+ bytes -= copy;
+
+ while (unlikely(!left && bytes)) {
+ iov++;
+ buf = iov->iov_base;
+ copy = min(bytes, iov->iov_len);
+ left = __copy_to_user_inatomic(buf, from, copy);
+ copy -= left;
+ skip = copy;
+ from += copy;
+ bytes -= copy;
+ }
+ if (likely(!bytes)) {
+ kunmap_atomic(kaddr);
+ goto done;
+ }
+ offset = from - kaddr;
+ buf += copy;
+ kunmap_atomic(kaddr);
+ copy = min(bytes, iov->iov_len - skip);
+ }
+ /* Too bad - revert to non-atomic kmap */
+ kaddr = kmap(page);
+ from = kaddr + offset;
+ left = __copy_to_user(buf, from, copy);
+ copy -= left;
+ skip += copy;
+ from += copy;
+ bytes -= copy;
+ while (unlikely(!left && bytes)) {
+ iov++;
+ buf = iov->iov_base;
+ copy = min(bytes, iov->iov_len);
+ left = __copy_to_user(buf, from, copy);
+ copy -= left;
+ skip = copy;
+ from += copy;
+ bytes -= copy;
+ }
+ kunmap(page);
+done:
+ i->count -= wanted - bytes;
+ i->nr_segs -= iov - i->iov;
+ i->iov = iov;
+ i->iov_offset = skip;
+ return wanted - bytes;
+}
+EXPORT_SYMBOL(copy_page_to_iter);
+
/**
* do_generic_file_read - generic file read routine
* @filp: the file to read
* @ppos: current file position
- * @desc: read_descriptor
+ * @iter: data destination
+ * @written: already copied
*
* This is a generic file read routine, and uses the
* mapping->a_ops->readpage() function for the actual low-level stuff.
@@ -1097,8 +1176,8 @@ static void shrink_readahead_size_eio(struct file *filp,
* This is really ugly. But the goto's actually try to clarify some
* of the logic when it comes to error handling etc.
*/
-static void do_generic_file_read(struct file *filp, loff_t *ppos,
- read_descriptor_t *desc)
+static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
+ struct iov_iter *iter, ssize_t written)
{
struct address_space *mapping = filp->f_mapping;
struct inode *inode = mapping->host;
@@ -1108,12 +1187,12 @@ static void do_generic_file_read(struct file *filp, loff_t *ppos,
pgoff_t prev_index;
unsigned long offset; /* offset into pagecache page */
unsigned int prev_offset;
- int error;
+ int error = 0;
index = *ppos >> PAGE_CACHE_SHIFT;
prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
- last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
+ last_index = (*ppos + iter->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
offset = *ppos & ~PAGE_CACHE_MASK;
for (;;) {
@@ -1148,7 +1227,7 @@ find_page:
if (!page->mapping)
goto page_not_up_to_date_locked;
if (!mapping->a_ops->is_partially_uptodate(page,
- offset, desc->count))
+ offset, iter->count))
goto page_not_up_to_date_locked;
unlock_page(page);
}
@@ -1198,24 +1277,23 @@ page_ok:
/*
* Ok, we have the page, and it's up-to-date, so
* now we can copy it to user space...
- *
- * The file_read_actor routine returns how many bytes were
- * actually used..
- * NOTE! This may not be the same as how much of a user buffer
- * we filled up (we may be padding etc), so we can only update
- * "pos" here (the actor routine has to update the user buffer
- * pointers and the remaining count).
*/
- ret = file_read_actor(desc, page, offset, nr);
+
+ ret = copy_page_to_iter(page, offset, nr, iter);
offset += ret;
index += offset >> PAGE_CACHE_SHIFT;
offset &= ~PAGE_CACHE_MASK;
prev_offset = offset;
page_cache_release(page);
- if (ret == nr && desc->count)
- continue;
- goto out;
+ written += ret;
+ if (!iov_iter_count(iter))
+ goto out;
+ if (ret < nr) {
+ error = -EFAULT;
+ goto out;
+ }
+ continue;
page_not_up_to_date:
/* Get exclusive access to the page ... */
@@ -1250,6 +1328,7 @@ readpage:
if (unlikely(error)) {
if (error == AOP_TRUNCATED_PAGE) {
page_cache_release(page);
+ error = 0;
goto find_page;
}
goto readpage_error;
@@ -1280,7 +1359,6 @@ readpage:
readpage_error:
/* UHHUH! A synchronous read error occurred. Report it */
- desc->error = error;
page_cache_release(page);
goto out;
@@ -1291,16 +1369,17 @@ no_cached_page:
*/
page = page_cache_alloc_cold(mapping);
if (!page) {
- desc->error = -ENOMEM;
+ error = -ENOMEM;
goto out;
}
error = add_to_page_cache_lru(page, mapping,
index, GFP_KERNEL);
if (error) {
page_cache_release(page);
- if (error == -EEXIST)
+ if (error == -EEXIST) {
+ error = 0;
goto find_page;
- desc->error = error;
+ }
goto out;
}
goto readpage;
@@ -1313,44 +1392,7 @@ out:
*ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
file_accessed(filp);
-}
-
-int file_read_actor(read_descriptor_t *desc, struct page *page,
- unsigned long offset, unsigned long size)
-{
- char *kaddr;
- unsigned long left, count = desc->count;
-
- if (size > count)
- size = count;
-
- /*
- * Faults on the destination of a read are common, so do it before
- * taking the kmap.
- */
- if (!fault_in_pages_writeable(desc->arg.buf, size)) {
- kaddr = kmap_atomic(page);
- left = __copy_to_user_inatomic(desc->arg.buf,
- kaddr + offset, size);
- kunmap_atomic(kaddr);
- if (left == 0)
- goto success;
- }
-
- /* Do it the slow way */
- kaddr = kmap(page);
- left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
- kunmap(page);
-
- if (left) {
- size -= left;
- desc->error = -EFAULT;
- }
-success:
- desc->count = count - size;
- desc->written += size;
- desc->arg.buf += size;
- return size;
+ return written ? written : error;
}
/*
@@ -1408,14 +1450,15 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
{
struct file *filp = iocb->ki_filp;
ssize_t retval;
- unsigned long seg = 0;
size_t count;
loff_t *ppos = &iocb->ki_pos;
+ struct iov_iter i;
count = 0;
retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
if (retval)
return retval;
+ iov_iter_init(&i, iov, nr_segs, count, 0);
/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
if (filp->f_flags & O_DIRECT) {
@@ -1437,6 +1480,11 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
if (retval > 0) {
*ppos = pos + retval;
count -= retval;
+ /*
+ * If we did a short DIO read we need to skip the
+ * section of the iov that we've already read data into.
+ */
+ iov_iter_advance(&i, retval);
}
/*
@@ -1453,39 +1501,7 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
}
}
- count = retval;
- for (seg = 0; seg < nr_segs; seg++) {
- read_descriptor_t desc;
- loff_t offset = 0;
-
- /*
- * If we did a short DIO read we need to skip the section of the
- * iov that we've already read data into.
- */
- if (count) {
- if (count > iov[seg].iov_len) {
- count -= iov[seg].iov_len;
- continue;
- }
- offset = count;
- count = 0;
- }
-
- desc.written = 0;
- desc.arg.buf = iov[seg].iov_base + offset;
- desc.count = iov[seg].iov_len - offset;
- if (desc.count == 0)
- continue;
- desc.error = 0;
- do_generic_file_read(filp, ppos, &desc);
- retval += desc.written;
- if (desc.error) {
- retval = retval ?: desc.error;
- break;
- }
- if (desc.count > 0)
- break;
- }
+ retval = do_generic_file_read(filp, ppos, &i, retval);
out:
return retval;
}
diff --git a/mm/shmem.c b/mm/shmem.c
index 9398e6c..17d3799d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1462,13 +1462,25 @@ shmem_write_end(struct file *file, struct address_space *mapping,
return copied;
}
-static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc)
+static ssize_t shmem_file_aio_read(struct kiocb *iocb,
+ const struct iovec *iov, unsigned long nr_segs, loff_t pos)
{
- struct inode *inode = file_inode(filp);
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file_inode(file);
struct address_space *mapping = inode->i_mapping;
pgoff_t index;
unsigned long offset;
enum sgp_type sgp = SGP_READ;
+ int error;
+ ssize_t retval;
+ size_t count;
+ loff_t *ppos = &iocb->ki_pos;
+ struct iov_iter iter;
+
+ retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
+ if (retval)
+ return retval;
+ iov_iter_init(&iter, iov, nr_segs, count, 0);
/*
* Might this read be for a stacking filesystem? Then when reading
@@ -1496,10 +1508,10 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
break;
}
- desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
- if (desc->error) {
- if (desc->error == -EINVAL)
- desc->error = 0;
+ error = shmem_getpage(inode, index, &page, sgp, NULL);
+ if (error) {
+ if (error == -EINVAL)
+ error = 0;
break;
}
if (page)
@@ -1543,61 +1555,26 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
/*
* Ok, we have the page, and it's up-to-date, so
* now we can copy it to user space...
- *
- * The actor routine returns how many bytes were actually used..
- * NOTE! This may not be the same as how much of a user buffer
- * we filled up (we may be padding etc), so we can only update
- * "pos" here (the actor routine has to update the user buffer
- * pointers and the remaining count).
*/
- ret = file_read_actor(desc, page, offset, nr);
+ ret = copy_page_to_iter(page, offset, nr, &iter);
+ retval += ret;
offset += ret;
index += offset >> PAGE_CACHE_SHIFT;
offset &= ~PAGE_CACHE_MASK;
page_cache_release(page);
- if (ret != nr || !desc->count)
+ if (!iov_iter_count(&iter))
break;
-
+ if (ret < nr) {
+ error = -EFAULT;
+ break;
+ }
cond_resched();
}
*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
- file_accessed(filp);
-}
-
-static ssize_t shmem_file_aio_read(struct kiocb *iocb,
- const struct iovec *iov, unsigned long nr_segs, loff_t pos)
-{
- struct file *filp = iocb->ki_filp;
- ssize_t retval;
- unsigned long seg;
- size_t count;
- loff_t *ppos = &iocb->ki_pos;
-
- retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
- if (retval)
- return retval;
-
- for (seg = 0; seg < nr_segs; seg++) {
- read_descriptor_t desc;
-
- desc.written = 0;
- desc.arg.buf = iov[seg].iov_base;
- desc.count = iov[seg].iov_len;
- if (desc.count == 0)
- continue;
- desc.error = 0;
- do_shmem_file_read(filp, ppos, &desc);
- retval += desc.written;
- if (desc.error) {
- retval = retval ?: desc.error;
- break;
- }
- if (desc.count > 0)
- break;
- }
- return retval;
+ file_accessed(file);
+ return retval ? retval : error;
}
static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
OpenPOWER on IntegriCloud