[PATCH 03/16] fuse: Prepare to handle short reads

From: Maxim Patlasov
Date: Sat Jun 29 2013 - 13:42:52 EST


From: Pavel Emelyanov <xemul@xxxxxxxxxx>

A helper which gets called when read reports less bytes than was requested.
See patch #6 (trust kernel i_size only) for details.

Signed-off-by: Maxim Patlasov <MPatlasov@xxxxxxxxxxxxx>
Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxx>
---
fs/fuse/file.c | 21 +++++++++++++--------
1 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 6b6d307..ea70814 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -653,6 +653,15 @@ static void fuse_read_update_size(struct inode *inode, loff_t size,
spin_unlock(&fc->lock);
}

+static void fuse_short_read(struct fuse_req *req, struct inode *inode,
+ u64 attr_ver)
+{
+ size_t num_read = req->out.args[0].size;
+
+ loff_t pos = page_offset(req->pages[0]) + num_read;
+ fuse_read_update_size(inode, pos, attr_ver);
+}
+
static int fuse_readpage(struct file *file, struct page *page)
{
struct fuse_io_priv io = { .async = 0, .file = file };
@@ -690,18 +699,18 @@ static int fuse_readpage(struct file *file, struct page *page)
req->page_descs[0].length = count;
num_read = fuse_send_read(req, &io, pos, count, NULL);
err = req->out.h.error;
- fuse_put_request(fc, req);

if (!err) {
/*
* Short read means EOF. If file size is larger, truncate it
*/
if (num_read < count)
- fuse_read_update_size(inode, pos + num_read, attr_ver);
+ fuse_short_read(req, inode, attr_ver);

SetPageUptodate(page);
}

+ fuse_put_request(fc, req);
fuse_invalidate_attr(inode); /* atime changed */
out:
unlock_page(page);
@@ -724,13 +733,9 @@ static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_req *req)
/*
* Short read means EOF. If file size is larger, truncate it
*/
- if (!req->out.h.error && num_read < count) {
- loff_t pos;
+ if (!req->out.h.error && num_read < count)
+ fuse_short_read(req, inode, req->misc.read.attr_ver);

- pos = page_offset(req->pages[0]) + num_read;
- fuse_read_update_size(inode, pos,
- req->misc.read.attr_ver);
- }
fuse_invalidate_attr(inode); /* atime changed */
}


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