Hi,
Il 26/04/2013 14:06, Matthew Wilcox ha scritto:
On Fri, Apr 26, 2013 at 10:50:52AM +0200, Marco Stornelli wrote:
Replace file_start_write with file_start_write_killable where
possible.
I feel like I'm missing context here. Possibly because you only cc'd me
on patch 2/4. In particular, file_start_write doesn't exist upstream,
so I'm not sure what it's for. But returning 1 for non-regular files
looks dodgy:
The patch series is based on -next due to several changes done by Al
about fsfreeze. file_start_write_killable returns 1 because it's mainly
a wrapper of __st_start_write. __sb_start_write returns 1 when
everything is ok, 0 when the lock can't be gotten (we are using the
trylock version) and _now_ a value < 0 when something happens (i.e. -EINTR).
+static inline int file_start_write_killable(struct file *file)
+{
+ if (!S_ISREG(file_inode(file)->i_mode))
+ return 1;
+ return sb_start_write_killable(file_inode(file)->i_sb);
+}
+++ b/fs/aio.c
@@ -1103,8 +1103,11 @@ static ssize_t aio_rw_vect_retry(struct kiocb *iocb, int rw, aio_rw_op *rw_op)
if (iocb->ki_pos < 0)
return -EINVAL;
- if (rw == WRITE)
- file_start_write(file);
+ if (rw == WRITE) {
+ ret = file_start_write_killable(file);
+ if (ret < 0)
+ return ret;
+ }
do {
So ... it's OK to do this write to pipes/directories/devices/... ? Or is
that check always taken care of elsewhere? If so, why do we need this
check? I'm confused. None of the callers check for the 'ret == 1' case,
so I'm sure there's something wrong here, I just can't tell what it is.
See above.
+++ b/fs/read_write.c
@@ -438,17 +438,19 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_
ret = rw_verify_area(WRITE, file, pos, count);
if (ret >= 0) {
count = ret;
- file_start_write(file);
- if (file->f_op->write)
- ret = file->f_op->write(file, buf, count, pos);
- else
- ret = do_sync_write(file, buf, count, pos);
+ ret = file_start_write_killable(file);
if (ret > 0) {
- fsnotify_modify(file);
- add_wchar(current, ret);
+ if (file->f_op->write)
+ ret = file->f_op->write(file, buf, count, pos);
+ else
+ ret = do_sync_write(file, buf, count, pos);
+ if (ret > 0) {
+ fsnotify_modify(file);
+ add_wchar(current, ret);
+ }
+ inc_syscw(current);
+ file_end_write(file);
}
- inc_syscw(current);
- file_end_write(file);
}
return ret;
I don't like it that you've increased the indentation here. Better to do
a preliminary patch which just converts to our normal style with gotos. ie:
Ok, I can change the style here, no problem.
Marco
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