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 3e0fdb7..d2094e1 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1324,7 +1324,7 @@ EXPORT_SYMBOL_GPL(fuse_direct_io);
static ssize_t __fuse_direct_read(struct file *file, const struct iovec *iov,
unsigned long nr_segs, loff_t *ppos,
- struct kiocb *async)
+ struct kiocb *async, size_t count)
{
ssize_t res;
struct inode *inode = file->f_path.dentry->d_inode;
@@ -1332,8 +1332,7 @@ static ssize_t __fuse_direct_read(struct file *file,
const struct iovec *iov,
if (is_bad_inode(inode))
return -EIO;
- res = fuse_direct_io(file, iov, nr_segs, iov_length(iov, nr_segs),
- ppos, 0, async);
+ res = fuse_direct_io(file, iov, nr_segs, count, ppos, 0, async);
fuse_invalidate_attr(inode);
@@ -1344,7 +1343,7 @@ static ssize_t fuse_direct_read(struct file *file, char
__user *buf,
size_t count, loff_t *ppos)
{
struct iovec iov = { .iov_base = buf, .iov_len = count };
- return __fuse_direct_read(file, &iov, 1, ppos, NULL);
+ return __fuse_direct_read(file, &iov, 1, ppos, NULL, count);
}
static ssize_t __fuse_direct_write(struct file *file, const struct iovec *iov,
@@ -2405,8 +2404,15 @@ 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;
+ }
+
/* cannot write beyond eof asynchronously */
- if (is_sync_kiocb(iocb) || (offset + count <= i_size) || rw != WRITE) {
+ if (is_sync_kiocb(iocb) || (offset + count <= i_size)) {
struct fuse_io_priv *io;
io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
@@ -2429,7 +2435,8 @@ fuse_direct_IO(int rw, struct kiocb *iocb, const struct
iovec *iov,
if (rw == WRITE)
ret = __fuse_direct_write(file, iov, nr_segs, &pos, async_cb);
else
- ret = __fuse_direct_read(file, iov, nr_segs, &pos, async_cb);
+ ret = __fuse_direct_read(file, iov, nr_segs, &pos, async_cb,
+ count);
if (async_cb) {
fuse_aio_complete(async_cb->private, ret == count ? 0 : -EIO,
--
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