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authorAhelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>2023-07-03 16:42:13 +0200
committerChristian Brauner <brauner@kernel.org>2023-07-10 14:36:11 +0200
commit12ee4b66af34f8e72f3b2fd93a946a955efe7c86 (patch)
treefe5437f82cb470dce488406fa0b349185f84549a
parentba38980add7ffc9e674ada5b4ded4e7d14e76581 (diff)
splice: always fsnotify_access(in), fsnotify_modify(out) on success
The current behaviour caused an asymmetry where some write APIs (write, sendfile) would notify the written-to/read-from objects, but splice wouldn't. This affected userspace which uses inotify, most notably coreutils tail -f, to monitor pipes. If the pipe buffer had been filled by a splice-family function: * tail wouldn't know and thus wouldn't service the pipe, and * all writes to the pipe would block because it's full, thus service was denied. (For the particular case of tail -f this could be worked around with ---disable-inotify.) Fixes: 983652c69199 ("splice: report related fsnotify events") Link: https://lore.kernel.org/linux-fsdevel/jbyihkyk5dtaohdwjyivambb2gffyjs3dodpofafnkkunxq7bu@jngkdxx65pux/t/#u Link: https://bugs.debian.org/1039488 Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Acked-by: Jan Kara <jack@suse.cz> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Message-Id: <604ec704d933e0e0121d9e107ce914512e045fad.1688393619.git.nabijaczleweli@nabijaczleweli.xyz> Signed-off-by: Christian Brauner <brauner@kernel.org>
-rw-r--r--fs/splice.c32
1 files changed, 15 insertions, 17 deletions
diff --git a/fs/splice.c b/fs/splice.c
index 004eb1c4ce31..016b0a83df44 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1267,10 +1267,8 @@ long do_splice(struct file *in, loff_t *off_in, struct file *out,
if ((in->f_flags | out->f_flags) & O_NONBLOCK)
flags |= SPLICE_F_NONBLOCK;
- return splice_pipe_to_pipe(ipipe, opipe, len, flags);
- }
-
- if (ipipe) {
+ ret = splice_pipe_to_pipe(ipipe, opipe, len, flags);
+ } else if (ipipe) {
if (off_in)
return -ESPIPE;
if (off_out) {
@@ -1295,18 +1293,11 @@ long do_splice(struct file *in, loff_t *off_in, struct file *out,
ret = do_splice_from(ipipe, out, &offset, len, flags);
file_end_write(out);
- if (ret > 0)
- fsnotify_modify(out);
-
if (!off_out)
out->f_pos = offset;
else
*off_out = offset;
-
- return ret;
- }
-
- if (opipe) {
+ } else if (opipe) {
if (off_out)
return -ESPIPE;
if (off_in) {
@@ -1322,18 +1313,25 @@ long do_splice(struct file *in, loff_t *off_in, struct file *out,
ret = splice_file_to_pipe(in, opipe, &offset, len, flags);
- if (ret > 0)
- fsnotify_access(in);
-
if (!off_in)
in->f_pos = offset;
else
*off_in = offset;
+ } else {
+ ret = -EINVAL;
+ }
- return ret;
+ if (ret > 0) {
+ /*
+ * Generate modify out before access in:
+ * do_splice_from() may've already sent modify out,
+ * and this ensures the events get merged.
+ */
+ fsnotify_modify(out);
+ fsnotify_access(in);
}
- return -EINVAL;
+ return ret;
}
static long __do_splice(struct file *in, loff_t __user *off_in,