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Message-ID: <CALCETrVE2G4x9mL0-o1FDQPfc=qZzw10Cx6AgOdhwphSaCmyzw@mail.gmail.com> Date: Mon, 19 Aug 2013 20:20:12 -0700 From: Andy Lutomirski <luto@...capital.net> To: Dave Chinner <david@...morbit.com> Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>, "Theodore Ts'o" <tytso@....edu>, Dave Hansen <dave.hansen@...ux.intel.com>, xfs@....sgi.com, Jan Kara <jack@...e.cz>, Tim Chen <tim.c.chen@...ux.intel.com>, Christoph Hellwig <hch@...radead.org> Subject: Re: [PATCH v3 2/5] fs: Add inode_update_time_writable On Mon, Aug 19, 2013 at 7:28 PM, Dave Chinner <david@...morbit.com> wrote: > On Fri, Aug 16, 2013 at 04:22:09PM -0700, Andy Lutomirski wrote: >> This is like file_update_time, except that it acts on a struct inode * >> instead of a struct file *. >> >> Signed-off-by: Andy Lutomirski <luto@...capital.net> >> --- >> fs/inode.c | 72 ++++++++++++++++++++++++++++++++++++++++++------------ >> include/linux/fs.h | 1 + >> 2 files changed, 58 insertions(+), 15 deletions(-) >> [...] >> + >> +int inode_update_time_writable(struct inode *inode) >> +{ >> + struct timespec now; >> + int sync_it = prepare_update_cmtime(inode, &now); >> + int ret; >> + >> + if (!sync_it) >> + return 0; >> + >> + /* sb_start_pagefault and update_time can both sleep. */ >> + sb_start_pagefault(inode->i_sb); >> + ret = update_time(inode, &now, sync_it); >> + sb_end_pagefault(inode->i_sb); > > This gets called from the writeback path - you can't use > sb_start_pagefault/sb_end_pagefault in that path. The race I'm worried about is: - mmap - write to the mapping - remount ro - flush_cmtime -> inode_update_time_writable This may be impossible, in which case I'm okay, but it's nice to have a sanity check. I'll see if I can figure out how to do that. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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