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authorMiklos Szeredi <mszeredi@redhat.com>2020-01-16 11:09:36 +0100
committerMiklos Szeredi <mszeredi@redhat.com>2020-01-16 11:09:36 +0100
commit7df1e988c723a066754090b22d047c3225342152 (patch)
tree41e759da1284e222614b1982b109844bcb98470a
parente42617b825f8073569da76dc4510bfa019b1c35a (diff)
fuse: fix fuse_send_readpages() in the syncronous read case
Buffered read in fuse normally goes via: -> generic_file_buffered_read() -> fuse_readpages() -> fuse_send_readpages() ->fuse_simple_request() [called since v5.4] In the case of a read request, fuse_simple_request() will return a non-negative bytecount on success or a negative error value. A positive bytecount was taken to be an error and the PG_error flag set on the page. This resulted in generic_file_buffered_read() falling back to ->readpage(), which would repeat the read request and succeed. Because of the repeated read succeeding the bug was not detected with regression tests or other use cases. The FTP module in GVFS however fails the second read due to the non-seekable nature of FTP downloads. Fix by checking and ignoring positive return value from fuse_simple_request(). Reported-by: Ondrej Holy <oholy@redhat.com> Link: https://gitlab.gnome.org/GNOME/gvfs/issues/441 Fixes: 134831e36bbd ("fuse: convert readpages to simple api") Cc: <stable@vger.kernel.org> # v5.4 Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
-rw-r--r--fs/fuse/file.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index a63d779eac10..ce715380143c 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -882,6 +882,7 @@ static void fuse_send_readpages(struct fuse_io_args *ia, struct file *file)
struct fuse_args_pages *ap = &ia->ap;
loff_t pos = page_offset(ap->pages[0]);
size_t count = ap->num_pages << PAGE_SHIFT;
+ ssize_t res;
int err;
ap->args.out_pages = true;
@@ -896,7 +897,8 @@ static void fuse_send_readpages(struct fuse_io_args *ia, struct file *file)
if (!err)
return;
} else {
- err = fuse_simple_request(fc, &ap->args);
+ res = fuse_simple_request(fc, &ap->args);
+ err = res < 0 ? res : 0;
}
fuse_readpages_end(fc, &ap->args, err);
}