diff options
| -rw-r--r-- | fs/read_write.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/fs/read_write.c b/fs/read_write.c index 969a6d9..5cc6924 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -50,6 +50,14 @@ generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin) offset += inode->i_size; break; case SEEK_CUR: + /* + * Here we special-case the lseek(fd, 0, SEEK_CUR) + * position-querying operation. Avoid rewriting the "same" + * f_pos value back to the file because a concurrent read(), + * write() or lseek() might have altered it + */ + if (offset == 0) + return file->f_pos; offset += file->f_pos; break; } @@ -105,6 +113,10 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin) offset += i_size_read(file->f_path.dentry->d_inode); break; case SEEK_CUR: + if (offset == 0) { + retval = file->f_pos; + goto out; + } offset += file->f_pos; } retval = -EINVAL; @@ -115,6 +127,7 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin) } retval = offset; } +out: unlock_kernel(); return retval; } |