Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753018AbbDDTNp (ORCPT ); Sat, 4 Apr 2015 15:13:45 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:25371 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752830AbbDDTNj (ORCPT ); Sat, 4 Apr 2015 15:13:39 -0400 From: Dmitry Monakhov To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, Dmitry Monakhov Subject: [PATCH 01/16] fs: save file->f_flags to kiocb->ki_flags Date: Sat, 4 Apr 2015 23:13:10 +0400 Message-Id: <1428174805-853-2-git-send-email-dmonakhov@openvz.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1428174805-853-1-git-send-email-dmonakhov@openvz.org> References: <1428174805-853-1-git-send-email-dmonakhov@openvz.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4638 Lines: 147 There are many places inside vfs/fs where code flow depends on file->f_flags, but this check is racy because one can change it via fcntl(,F_SETFL,) For example O_DIRECT usually flag checked twice: xxx_file_write_iter -> check O_DIRECT, and perform some optimization ->__generic_file_write_iter -> check O_DIRECT, which may break things: for example http://www.spinics.net/lists/linux-ext4/msg45683.html For that reason some filesystems simply do not use __generic_file_write_iter() which result in code duplication. Right way to fix this is to save volatile flags inside kiocb->ki_flags similar to ->ki_pos Other private discussion: message-id:20141218105101.GD13705@quack.suse.cz This patch store O_DIRECT|O_APPEND|O_NONBLOCK|O_NDELAY to kiocb->ki_flags on kiocb initialization. Signed-off-by: Dmitry Monakhov --- fs/aio.c | 7 ++++--- fs/read_write.c | 20 ++++++++++++++++++++ include/linux/fs.h | 30 +++++++++++++++++++++++++++--- 3 files changed, 51 insertions(+), 6 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 3b8467a..f58c4d6 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1482,6 +1482,7 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, struct iocb *iocb, bool compat) { struct aio_kiocb *req; + struct file* filp; ssize_t ret; /* enforce forwards compatibility on users */ @@ -1504,14 +1505,14 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, if (unlikely(!req)) return -EAGAIN; - req->common.ki_filp = fget(iocb->aio_fildes); - if (unlikely(!req->common.ki_filp)) { + filp = fget(iocb->aio_fildes); + if (unlikely(!filp)) { ret = -EBADF; goto out_put_req; } + kiocb_init_file(&req->common, filp); req->common.ki_pos = iocb->aio_offset; req->common.ki_complete = aio_complete; - req->common.ki_flags = 0; if (iocb->aio_flags & IOCB_FLAG_RESFD) { /* diff --git a/fs/read_write.c b/fs/read_write.c index 69128b3..00e1ca4 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -41,6 +41,26 @@ static inline int unsigned_offsets(struct file *file) return file->f_mode & FMODE_UNSIGNED_OFFSET; } +void kiocb_init_file(struct kiocb *kiocb, struct file *filp) +{ + kiocb->ki_flags = 0; + kiocb->ki_filp = filp; + + /* Socket aio */ + if (kiocb->ki_filp == NULL) + return; + + if (filp->f_flags & O_APPEND) + kiocb->ki_flags |= IOCB_APPEND; + if (filp->f_flags & O_NONBLOCK) + kiocb->ki_flags |= IOCB_NONBLOCK; + if (filp->f_flags & O_NDELAY) + kiocb->ki_flags |= IOCB_NDELAY; + if (filp->f_flags & O_DIRECT) + kiocb->ki_flags |= IOCB_DIRECT; +} +EXPORT_SYMBOL(kiocb_init_file); + /** * vfs_setpos - update the file offset for lseek * @file: file structure in question diff --git a/include/linux/fs.h b/include/linux/fs.h index dfbd88a..4c20030 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -315,6 +315,10 @@ struct address_space; struct writeback_control; #define IOCB_EVENTFD (1 << 0) +#define IOCB_APPEND (1 << 1) +#define IOCB_NONBLOCK (1 << 2) +#define IOCB_NDELAY (1 << 3) +#define IOCB_DIRECT (1 << 4) struct kiocb { struct file *ki_filp; @@ -329,11 +333,11 @@ static inline bool is_sync_kiocb(struct kiocb *kiocb) return kiocb->ki_complete == NULL; } +extern void kiocb_init_file(struct kiocb *kiocb, struct file *filp); static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp) { - *kiocb = (struct kiocb) { - .ki_filp = filp, - }; + memset(kiocb, 0 , sizeof(*kiocb)); + kiocb_init_file(kiocb, filp); } /* @@ -2776,6 +2780,26 @@ extern int generic_show_options(struct seq_file *m, struct dentry *root); extern void save_mount_options(struct super_block *sb, char *options); extern void replace_mount_options(struct super_block *sb, char *options); +static inline bool is_append_kiocb(struct kiocb *kiocb) +{ + return kiocb->ki_flags & IOCB_APPEND; +} + +static inline bool is_direct_kiocb(struct kiocb *kiocb) +{ + return (kiocb->ki_flags & IOCB_DIRECT) | + IS_DAX(file_inode(kiocb->ki_filp)); + +} + + +static inline bool is_nonblock_kiocb(struct kiocb *kiocb) +{ + return kiocb->ki_flags & IOCB_NONBLOCK; +} + +/* XXX: this is obsolete helper, and will be removed soon. + * One should use io_direct_kiocb() instead */ static inline bool io_is_direct(struct file *filp) { return (filp->f_flags & O_DIRECT) || IS_DAX(file_inode(filp)); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/