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fuse: pass iov[] to fuse_get_user_pages()
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The patch makes preliminary work for the next patch optimizing scatter-gather
direct IO. The idea is to allow fuse_get_user_pages() to pack as many iov-s
to each fuse request as possible. So, here we only rework all related
call-paths to carry iov[] from fuse_direct_IO() to fuse_get_user_pages().

Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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Maxim Patlasov authored and Miklos Szeredi committed Jan 24, 2013
1 parent d28574e commit b98d023
Showing 1 changed file with 49 additions and 54 deletions.
103 changes: 49 additions & 54 deletions fs/fuse/file.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1056,25 +1056,31 @@ static inline void fuse_page_descs_length_init(struct fuse_req *req)
req->page_descs[i].offset;
}

static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,
static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
size_t *nbytesp, int write)
{
size_t nbytes = *nbytesp;
unsigned long user_addr = (unsigned long) buf;
unsigned offset = user_addr & ~PAGE_MASK;
size_t frag_size = min(iov_iter_single_seg_count(ii), nbytes);
unsigned long user_addr;
unsigned offset;
int npages;

user_addr = (unsigned long)ii->iov->iov_base + ii->iov_offset;
offset = user_addr & ~PAGE_MASK;

/* Special case for kernel I/O: can copy directly into the buffer */
if (segment_eq(get_fs(), KERNEL_DS)) {
if (write)
req->in.args[1].value = (void *) user_addr;
else
req->out.args[0].value = (void *) user_addr;

iov_iter_advance(ii, frag_size);
*nbytesp = frag_size;
return 0;
}

nbytes = min_t(size_t, nbytes, FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
nbytes = min_t(size_t, frag_size, FUSE_MAX_PAGES_PER_REQ << PAGE_SHIFT);
npages = (nbytes + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
npages = clamp(npages, 1, FUSE_MAX_PAGES_PER_REQ);
npages = get_user_pages_fast(user_addr, npages, !write, req->pages);
Expand All @@ -1092,24 +1098,29 @@ static int fuse_get_user_pages(struct fuse_req *req, const char __user *buf,

nbytes = (req->num_pages << PAGE_SHIFT) - req->page_descs[0].offset;

if (*nbytesp < nbytes)
if (frag_size < nbytes)
req->page_descs[req->num_pages - 1].length -=
nbytes - *nbytesp;
nbytes - frag_size;

*nbytesp = min(*nbytesp, nbytes);
*nbytesp = min(frag_size, nbytes);
iov_iter_advance(ii, *nbytesp);

return 0;
}

ssize_t fuse_direct_io(struct file *file, const char __user *buf,
size_t count, loff_t *ppos, int write)
static ssize_t __fuse_direct_io(struct file *file, const struct iovec *iov,
unsigned long nr_segs, size_t count,
loff_t *ppos, int write)
{
struct fuse_file *ff = file->private_data;
struct fuse_conn *fc = ff->fc;
size_t nmax = write ? fc->max_write : fc->max_read;
loff_t pos = *ppos;
ssize_t res = 0;
struct fuse_req *req;
struct iov_iter ii;

iov_iter_init(&ii, iov, nr_segs, count, 0);

req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
if (IS_ERR(req))
Expand All @@ -1119,7 +1130,7 @@ ssize_t fuse_direct_io(struct file *file, const char __user *buf,
size_t nres;
fl_owner_t owner = current->files;
size_t nbytes = min(count, nmax);
int err = fuse_get_user_pages(req, buf, &nbytes, write);
int err = fuse_get_user_pages(req, &ii, &nbytes, write);
if (err) {
res = err;
break;
Expand All @@ -1142,7 +1153,6 @@ ssize_t fuse_direct_io(struct file *file, const char __user *buf,
count -= nres;
res += nres;
pos += nres;
buf += nres;
if (nres != nbytes)
break;
if (count) {
Expand All @@ -1159,33 +1169,49 @@ ssize_t fuse_direct_io(struct file *file, const char __user *buf,

return res;
}

ssize_t fuse_direct_io(struct file *file, const char __user *buf,
size_t count, loff_t *ppos, int write)
{
struct iovec iov = { .iov_base = (void *)buf, .iov_len = count };
return __fuse_direct_io(file, &iov, 1, count, ppos, write);
}
EXPORT_SYMBOL_GPL(fuse_direct_io);

static ssize_t fuse_direct_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
static ssize_t __fuse_direct_read(struct file *file, const struct iovec *iov,
unsigned long nr_segs, loff_t *ppos)
{
ssize_t res;
struct inode *inode = file->f_path.dentry->d_inode;

if (is_bad_inode(inode))
return -EIO;

res = fuse_direct_io(file, buf, count, ppos, 0);
res = __fuse_direct_io(file, iov, nr_segs, iov_length(iov, nr_segs),
ppos, 0);

fuse_invalidate_attr(inode);

return res;
}

static ssize_t __fuse_direct_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
static ssize_t fuse_direct_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
struct iovec iov = { .iov_base = (void *)buf, .iov_len = count };
return __fuse_direct_read(file, &iov, 1, ppos);
}

static ssize_t __fuse_direct_write(struct file *file, const struct iovec *iov,
unsigned long nr_segs, loff_t *ppos)
{
struct inode *inode = file->f_path.dentry->d_inode;
size_t count = iov_length(iov, nr_segs);
ssize_t res;

res = generic_write_checks(file, ppos, &count, 0);
if (!res) {
res = fuse_direct_io(file, buf, count, ppos, 1);
res = __fuse_direct_io(file, iov, nr_segs, count, ppos, 1);
if (res > 0)
fuse_write_update_size(inode, *ppos);
}
Expand All @@ -1198,6 +1224,7 @@ static ssize_t __fuse_direct_write(struct file *file, const char __user *buf,
static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct iovec iov = { .iov_base = (void *)buf, .iov_len = count };
struct inode *inode = file->f_path.dentry->d_inode;
ssize_t res;

Expand All @@ -1206,7 +1233,7 @@ static ssize_t fuse_direct_write(struct file *file, const char __user *buf,

/* Don't allow parallel writes to the same file */
mutex_lock(&inode->i_mutex);
res = __fuse_direct_write(file, buf, count, ppos);
res = __fuse_direct_write(file, &iov, 1, ppos);
mutex_unlock(&inode->i_mutex);

return res;
Expand Down Expand Up @@ -2167,41 +2194,6 @@ int fuse_notify_poll_wakeup(struct fuse_conn *fc,
return 0;
}

static ssize_t fuse_loop_dio(struct file *filp, const struct iovec *iov,
unsigned long nr_segs, loff_t *ppos, int rw)
{
const struct iovec *vector = iov;
ssize_t ret = 0;

while (nr_segs > 0) {
void __user *base;
size_t len;
ssize_t nr;

base = vector->iov_base;
len = vector->iov_len;
vector++;
nr_segs--;

if (rw == WRITE)
nr = __fuse_direct_write(filp, base, len, ppos);
else
nr = fuse_direct_read(filp, base, len, ppos);

if (nr < 0) {
if (!ret)
ret = nr;
break;
}
ret += nr;
if (nr != len)
break;
}

return ret;
}


static ssize_t
fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
loff_t offset, unsigned long nr_segs)
Expand All @@ -2213,7 +2205,10 @@ fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
file = iocb->ki_filp;
pos = offset;

ret = fuse_loop_dio(file, iov, nr_segs, &pos, rw);
if (rw == WRITE)
ret = __fuse_direct_write(file, iov, nr_segs, &pos);
else
ret = __fuse_direct_read(file, iov, nr_segs, &pos);

return ret;
}
Expand Down

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