If user requested direct read beyond EOF, we can skip sending fuse requests
for positions beyond EOF because userspace would ACK them with zero bytes read
anyway. We can trust to i_size in fuse_direct_IO for such cases because it's
called from fuse_file_aio_read() and the latter updates fuse attributes
including i_size.
Signed-off-by: Maxim Patlasov <mpatla...@parallels.com>
---
fs/fuse/file.c | 19 +++++++++++++------
1 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index b6e9b8d..ceacd20 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1322,7 +1322,8 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, const
struct iovec *iov,
EXPORT_SYMBOL_GPL(fuse_direct_io);
static ssize_t __fuse_direct_read(struct fuse_io_priv *io, const struct iovec
*iov,
- unsigned long nr_segs, loff_t *ppos)
+ unsigned long nr_segs, loff_t *ppos,
+ size_t count)
{
ssize_t res;
struct file *file = io->file;
@@ -1331,8 +1332,7 @@ static ssize_t __fuse_direct_read(struct fuse_io_priv
*io, const struct iovec *i
if (is_bad_inode(inode))
return -EIO;
- res = fuse_direct_io(io, iov, nr_segs, iov_length(iov, nr_segs),
- ppos, 0);
+ res = fuse_direct_io(io, iov, nr_segs, count, ppos, 0);
fuse_invalidate_attr(inode);
@@ -1344,7 +1344,7 @@ static ssize_t fuse_direct_read(struct file *file, char
__user *buf,
{
struct fuse_io_priv io = { .async = 0, .file = file };
struct iovec iov = { .iov_base = buf, .iov_len = count };
- return __fuse_direct_read(&io, &iov, 1, ppos);
+ return __fuse_direct_read(&io, &iov, 1, ppos, count);
}
static ssize_t __fuse_direct_write(struct fuse_io_priv *io, const struct iovec
*iov,
@@ -2404,6 +2404,13 @@ fuse_direct_IO(int rw, struct kiocb *iocb, const struct
iovec *iov,
inode = file->f_mapping->host;
i_size = i_size_read(inode);
+ /* optimization for short read */
+ if (rw != WRITE && offset + count > i_size) {
+ if (offset >= i_size)
+ return 0;
+ count = i_size - offset;
+ }
+
io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
if (!io)
return -ENOMEM;
@@ -2427,13 +2434,13 @@ fuse_direct_IO(int rw, struct kiocb *iocb, const struct
iovec *iov,
* to wait on real async I/O requests, so we must submit this request
* synchronously.
*/
- if (!is_sync_kiocb(iocb) && (offset + count > i_size) && rw == WRITE)
+ if (!is_sync_kiocb(iocb) && (offset + count > i_size))
io->async = 0;
if (rw == WRITE)
ret = __fuse_direct_write(io, iov, nr_segs, &pos);
else
- ret = __fuse_direct_read(io, iov, nr_segs, &pos);
+ ret = __fuse_direct_read(io, iov, nr_segs, &pos, count);
if (io->async) {
fuse_aio_complete(io, ret == count ? 0 : -EIO, -1);
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
