diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/file_table.c | 1 | ||||
| -rw-r--r-- | fs/namei.c | 2 | ||||
| -rw-r--r-- | fs/open.c | 4 | ||||
| -rw-r--r-- | fs/read_write.c | 54 |
4 files changed, 46 insertions, 15 deletions
diff --git a/fs/file_table.c b/fs/file_table.c index 5fff9030be34..5b24008ea4f6 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -135,6 +135,7 @@ struct file *get_empty_filp(void) atomic_long_set(&f->f_count, 1); rwlock_init(&f->f_owner.lock); spin_lock_init(&f->f_lock); + mutex_init(&f->f_pos_lock); eventpoll_init_file(f); /* f->f_version: 0 */ return f; diff --git a/fs/namei.c b/fs/namei.c index 385f7817bfcc..2f730ef9b4b3 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1884,7 +1884,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, nd->path = f.file->f_path; if (flags & LOOKUP_RCU) { - if (f.need_put) + if (f.flags & FDPUT_FPUT) *fp = f.file; nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); rcu_read_lock(); diff --git a/fs/open.c b/fs/open.c index 4b3e1edf2fe4..b9ed8b25c108 100644 --- a/fs/open.c +++ b/fs/open.c @@ -705,6 +705,10 @@ static int do_dentry_open(struct file *f, return 0; } + /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */ + if (S_ISREG(inode->i_mode)) + f->f_mode |= FMODE_ATOMIC_POS; + f->f_op = fops_get(inode->i_fop); if (unlikely(WARN_ON(!f->f_op))) { error = -ENODEV; diff --git a/fs/read_write.c b/fs/read_write.c index edc5746a902a..932bb3414a96 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -264,10 +264,36 @@ loff_t vfs_llseek(struct file *file, loff_t offset, int whence) } EXPORT_SYMBOL(vfs_llseek); +/* + * We only lock f_pos if we have threads or if the file might be + * shared with another process. In both cases we'll have an elevated + * file count (done either by fdget() or by fork()). + */ +static inline struct fd fdget_pos(int fd) +{ + struct fd f = fdget(fd); + struct file *file = f.file; + + if (file && (file->f_mode & FMODE_ATOMIC_POS)) { + if (file_count(file) > 1) { + f.flags |= FDPUT_POS_UNLOCK; + mutex_lock(&file->f_pos_lock); + } + } + return f; +} + +static inline void fdput_pos(struct fd f) +{ + if (f.flags & FDPUT_POS_UNLOCK) + mutex_unlock(&f.file->f_pos_lock); + fdput(f); +} + SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence) { off_t retval; - struct fd f = fdget(fd); + struct fd f = fdget_pos(fd); if (!f.file) return -EBADF; @@ -278,7 +304,7 @@ SYSCALL_DEFINE3(lseek, unsigned int, fd, off_t, offset, unsigned int, whence) if (res != (loff_t)retval) retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */ } - fdput(f); + fdput_pos(f); return retval; } @@ -498,7 +524,7 @@ static inline void file_pos_write(struct file *file, loff_t pos) SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) { - struct fd f = fdget(fd); + struct fd f = fdget_pos(fd); ssize_t ret = -EBADF; if (f.file) { @@ -506,7 +532,7 @@ SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) ret = vfs_read(f.file, buf, count, &pos); if (ret >= 0) file_pos_write(f.file, pos); - fdput(f); + fdput_pos(f); } return ret; } @@ -514,7 +540,7 @@ SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf, size_t, count) { - struct fd f = fdget(fd); + struct fd f = fdget_pos(fd); ssize_t ret = -EBADF; if (f.file) { @@ -522,7 +548,7 @@ SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf, ret = vfs_write(f.file, buf, count, &pos); if (ret >= 0) file_pos_write(f.file, pos); - fdput(f); + fdput_pos(f); } return ret; @@ -797,7 +823,7 @@ EXPORT_SYMBOL(vfs_writev); SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec, unsigned long, vlen) { - struct fd f = fdget(fd); + struct fd f = fdget_pos(fd); ssize_t ret = -EBADF; if (f.file) { @@ -805,7 +831,7 @@ SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec, ret = vfs_readv(f.file, vec, vlen, &pos); if (ret >= 0) file_pos_write(f.file, pos); - fdput(f); + fdput_pos(f); } if (ret > 0) @@ -817,7 +843,7 @@ SYSCALL_DEFINE3(readv, unsigned long, fd, const struct iovec __user *, vec, SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec, unsigned long, vlen) { - struct fd f = fdget(fd); + struct fd f = fdget_pos(fd); ssize_t ret = -EBADF; if (f.file) { @@ -825,7 +851,7 @@ SYSCALL_DEFINE3(writev, unsigned long, fd, const struct iovec __user *, vec, ret = vfs_writev(f.file, vec, vlen, &pos); if (ret >= 0) file_pos_write(f.file, pos); - fdput(f); + fdput_pos(f); } if (ret > 0) @@ -968,7 +994,7 @@ COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd, const struct compat_iovec __user *,vec, compat_ulong_t, vlen) { - struct fd f = fdget(fd); + struct fd f = fdget_pos(fd); ssize_t ret; loff_t pos; @@ -978,7 +1004,7 @@ COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd, ret = compat_readv(f.file, vec, vlen, &pos); if (ret >= 0) f.file->f_pos = pos; - fdput(f); + fdput_pos(f); return ret; } @@ -1035,7 +1061,7 @@ COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd, const struct compat_iovec __user *, vec, compat_ulong_t, vlen) { - struct fd f = fdget(fd); + struct fd f = fdget_pos(fd); ssize_t ret; loff_t pos; @@ -1045,7 +1071,7 @@ COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd, ret = compat_writev(f.file, vec, vlen, &pos); if (ret >= 0) f.file->f_pos = pos; - fdput(f); + fdput_pos(f); return ret; } |