From db1dd4d376134eba0e08af523b61cc566a4ea1cd Mon Sep 17 00:00:00 2001 From: Jonathan Corbet Date: Fri, 6 Feb 2009 15:25:24 -0700 Subject: Use f_lock to protect f_flags Traditionally, changes to struct file->f_flags have been done under BKL protection, or with no protection at all. This patch causes all f_flags changes after file open/creation time to be done under protection of f_lock. This allows the removal of some BKL usage and fixes a number of longstanding (if microscopic) races. Reviewed-by: Christoph Hellwig Cc: Al Viro Signed-off-by: Jonathan Corbet --- fs/fcntl.c | 2 ++ fs/ioctl.c | 7 ++++--- fs/nfsd/vfs.c | 5 ++++- 3 files changed, 10 insertions(+), 4 deletions(-) (limited to 'fs') diff --git a/fs/fcntl.c b/fs/fcntl.c index bd215cc791d..04df8570a2d 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -189,7 +189,9 @@ static int setfl(int fd, struct file * filp, unsigned long arg) } } + spin_lock(&filp->f_lock); filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); + spin_unlock(&filp->f_lock); out: unlock_kernel(); return error; diff --git a/fs/ioctl.c b/fs/ioctl.c index 240ec63984c..421aab465da 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -404,10 +404,12 @@ static int ioctl_fionbio(struct file *filp, int __user *argp) if (O_NONBLOCK != O_NDELAY) flag |= O_NDELAY; #endif + spin_lock(&filp->f_lock); if (on) filp->f_flags |= flag; else filp->f_flags &= ~flag; + spin_unlock(&filp->f_lock); return error; } @@ -432,10 +434,12 @@ static int ioctl_fioasync(unsigned int fd, struct file *filp, if (error) return error; + spin_lock(&filp->f_lock); if (on) filp->f_flags |= FASYNC; else filp->f_flags &= ~FASYNC; + spin_unlock(&filp->f_lock); return error; } @@ -499,10 +503,7 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd, break; case FIONBIO: - /* BKL needed to avoid races tweaking f_flags */ - lock_kernel(); error = ioctl_fionbio(filp, argp); - unlock_kernel(); break; case FIOASYNC: diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 6e50aaa56ca..c165a6403df 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -998,8 +998,11 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file, if (!EX_ISSYNC(exp)) stable = 0; - if (stable && !EX_WGATHER(exp)) + if (stable && !EX_WGATHER(exp)) { + spin_lock(&file->f_lock); file->f_flags |= O_SYNC; + spin_unlock(&file->f_lock); + } /* Write the data. */ oldfs = get_fs(); set_fs(KERNEL_DS); -- cgit v1.2.3