There are multiple issues with the custom llseek implemented in ocfs2 for implementing SEEK_HOLE/SEEK_DATA. 1. It takes the inode->i_mutex lock before calling generic_file_llseek(), which is unnecessary. 2. It fails to take the filp->f_lock spinlock before modifying filp->f_pos and filp->f_version, which differs from generic_file_llseek(). 3. It does a offset > inode->i_sb->s_maxbytes check that permits seeking up to the maximum file size possible on the ocfs2 filesystem, even when it is past the end of the file. Seeking beyond that (if possible), would return EINVAL instead of ENXIO. 4. The switch statement tries to cover all whence values when in reality it should only care about SEEK_HOLE/SEEK_DATA. Any other cases should be passsed to generic_file_llseek(). btrfs_file_llseek() and ocfs2_file_llseek() are extremely similar and consequently, contain many of the same flaws. Li Dongyang filed a pull request with ZFSOnLinux for SEEK_HOLE/SEEK_DATA support that included a custom llseek function that appears to have been modelled after the one in ocfs2. The similarity was strong enough that it suffered from many of the same flaws, which I caught during review. I addressed the issues with his patch with one that I wrote. Since a small percentage of Gentoo Linux users are affected by these flaws, I decided to adapt that code that to btrfs (separate patch) and ocfs2. Note that commit 48802c8ae2a9d618ec734a61283d645ad527e06c by Jeff Liu at Oracle mostly addressed #3 in btrfs. The only lingering issue was that the offset > inode->i_sb->s_maxbytes check became dead code. The ocfs2 code was not fortunate enough to have had a similar correction until now. Signed-off-by: Richard Yao <ryao@xxxxxxxxxx> --- fs/ocfs2/file.c | 65 ++++++++++++++++++++++----------------------------------- 1 file changed, 25 insertions(+), 40 deletions(-) diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c index ff54014..84f8c9c 100644 --- a/fs/ocfs2/file.c +++ b/fs/ocfs2/file.c @@ -2615,54 +2615,39 @@ bail: } /* Refer generic_file_llseek_unlocked() */ -static loff_t ocfs2_file_llseek(struct file *file, loff_t offset, int whence) +static loff_t ocfs2_file_llseek(struct file *filp, loff_t offset, int whence) { - struct inode *inode = file->f_mapping->host; - int ret = 0; + if (whence == SEEK_DATA || whence == SEEK_HOLE) { + struct inode *inode = filp->f_mapping->host; + int ret; - mutex_lock(&inode->i_mutex); + if (offset < 0 && !(filp->f_mode & FMODE_UNSIGNED_OFFSET)) + return -EINVAL; - switch (whence) { - case SEEK_SET: - break; - case SEEK_END: - offset += inode->i_size; - break; - case SEEK_CUR: - if (offset == 0) { - offset = file->f_pos; - goto out; + if (offset >= i_size_read(inode)) { + return -ENXIO; } - offset += file->f_pos; - break; - case SEEK_DATA: - case SEEK_HOLE: - ret = ocfs2_seek_data_hole_offset(file, &offset, whence); - if (ret) - goto out; - break; - default: - ret = -EINVAL; - goto out; - } - if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) - ret = -EINVAL; - if (!ret && offset > inode->i_sb->s_maxbytes) - ret = -EINVAL; - if (ret) - goto out; + mutex_lock(&inode->i_mutex); + ret = ocfs2_seek_data_hole_offset(filp, &offset, whence); + mutex_unlock(&inode->i_mutex); + + if (ret) { + return ret; + } - if (offset != file->f_pos) { - file->f_pos = offset; - file->f_version = 0; + if (offset != filp->f_pos) { + spin_lock(&filp->f_lock); + filp->f_pos = offset; + filp->f_version = 0; + spin_unlock(&filp->f_lock); + } + + return offset; } -out: - mutex_unlock(&inode->i_mutex); - if (ret) - return ret; - return offset; + return generic_file_llseek(filp, offset, whence); + } const struct inode_operations ocfs2_file_iops = { -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html