| Message ID | 1392370263-10364-2-git-send-email-piastry@etersoft.ru (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 14 Feb 2014 13:31:03 +0400 Pavel Shilovsky <piastry@etersoft.ru> wrote: > and use generic_file_aio_write rather than __generic_file_aio_write > in cifs_writev. > > Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru> Al reported this, so you may want to add: Reported-by: Al Viro <viro@ZenIV.linux.org.uk> ...and cc him. > --- > fs/cifs/file.c | 24 ++++++------------------ > 1 file changed, 6 insertions(+), 18 deletions(-) > > diff --git a/fs/cifs/file.c b/fs/cifs/file.c > index a7eda8e..d34dc3b 100644 > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c > @@ -2539,31 +2539,19 @@ cifs_writev(struct kiocb *iocb, const struct iovec *iov, > struct cifsInodeInfo *cinode = CIFS_I(inode); > struct TCP_Server_Info *server = tlink_tcon(cfile->tlink)->ses->server; > ssize_t rc = -EACCES; > + loff_t lock_pos = pos; > > - BUG_ON(iocb->ki_pos != pos); > - > + if (file->f_flags & O_APPEND) > + lock_pos = i_size_read(inode); Hmm... I'll note that when we do the i_size_read in generic_write_checks, the i_mutex is held. It's not held here though -- is that a potential race? Could the i_size change after you check for locks but before you do the I/O? vfs.txt says: "Adding and removing pages to/from an address_space is protected by the inode's i_mutex." That said, I don't have a great feel for how the locking rules work in this regard... > /* > * We need to hold the sem to be sure nobody modifies lock list > * with a brlock that prevents writing. > */ > down_read(&cinode->lock_sem); > - if (!cifs_find_lock_conflict(cfile, pos, iov_length(iov, nr_segs), > + if (!cifs_find_lock_conflict(cfile, lock_pos, iov_length(iov, nr_segs), > server->vals->exclusive_lock_type, NULL, > - CIFS_WRITE_OP)) { > - mutex_lock(&inode->i_mutex); > - rc = __generic_file_aio_write(iocb, iov, nr_segs, > - &iocb->ki_pos); > - mutex_unlock(&inode->i_mutex); > - } > - > - if (rc > 0) { > - ssize_t err; > - > - err = generic_write_sync(file, iocb->ki_pos - rc, rc); > - if (err < 0) > - rc = err; > - } > - > + CIFS_WRITE_OP)) > + rc = generic_file_aio_write(iocb, iov, nr_segs, pos); > up_read(&cinode->lock_sem); > return rc; > }
diff --git a/fs/cifs/file.c b/fs/cifs/file.c index a7eda8e..d34dc3b 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2539,31 +2539,19 @@ cifs_writev(struct kiocb *iocb, const struct iovec *iov, struct cifsInodeInfo *cinode = CIFS_I(inode); struct TCP_Server_Info *server = tlink_tcon(cfile->tlink)->ses->server; ssize_t rc = -EACCES; + loff_t lock_pos = pos; - BUG_ON(iocb->ki_pos != pos); - + if (file->f_flags & O_APPEND) + lock_pos = i_size_read(inode); /* * We need to hold the sem to be sure nobody modifies lock list * with a brlock that prevents writing. */ down_read(&cinode->lock_sem); - if (!cifs_find_lock_conflict(cfile, pos, iov_length(iov, nr_segs), + if (!cifs_find_lock_conflict(cfile, lock_pos, iov_length(iov, nr_segs), server->vals->exclusive_lock_type, NULL, - CIFS_WRITE_OP)) { - mutex_lock(&inode->i_mutex); - rc = __generic_file_aio_write(iocb, iov, nr_segs, - &iocb->ki_pos); - mutex_unlock(&inode->i_mutex); - } - - if (rc > 0) { - ssize_t err; - - err = generic_write_sync(file, iocb->ki_pos - rc, rc); - if (err < 0) - rc = err; - } - + CIFS_WRITE_OP)) + rc = generic_file_aio_write(iocb, iov, nr_segs, pos); up_read(&cinode->lock_sem); return rc; }
and use generic_file_aio_write rather than __generic_file_aio_write in cifs_writev. Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru> --- fs/cifs/file.c | 24 ++++++------------------ 1 file changed, 6 insertions(+), 18 deletions(-)