/*
 *  linux/fs/ext4/file.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/file.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  ext4 fs regular file handling primitives
 *
 *  64-bit file support on 64-bit platforms by Jakub Jelinek
 *      (jj@sunsite.ms.mff.cuni.cz)
 */

#include <linux/time.h>
#include <linux/fs.h>
#include <linux/jbd2.h>
#include <linux/mount.h>
#include <linux/path.h>
#include <linux/quotaops.h>
#include "ext4.h"
#include "ext4_jbd2.h"
#include "xattr.h"
#include "acl.h"

/*
 * Called when an inode is released. Note that this is different
 * from ext4_file_open: open gets called at every open, but release
 * gets called only when /all/ the files are closed.
 */
static int ext4_release_file(struct inode *inode, struct file *filp)
{
        if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
                ext4_alloc_da_blocks(inode);
                ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
        }
        /* if we are the last writer on the inode, drop the block reservation */
        if ((filp->f_mode & FMODE_WRITE) &&
                        (atomic_read(&inode->i_writecount) == 1) &&
                        !EXT4_I(inode)->i_reserved_data_blocks)
        {
                down_write(&EXT4_I(inode)->i_data_sem);
                ext4_discard_preallocations(inode);
                up_write(&EXT4_I(inode)->i_data_sem);
        }
        if (is_dx(inode) && filp->private_data)
                ext4_htree_free_dir_info(filp->private_data);

        return 0;
}

static void ext4_aiodio_wait(struct inode *inode)
{
        wait_queue_head_t *wq = ext4_ioend_wq(inode);

        wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_aiodio_unwritten) == 0));
}

/*
 * This tests whether the IO in question is block-aligned or not.
 * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
 * are converted to written only after the IO is complete.  Until they are
 * mapped, these blocks appear as holes, so dio_zero_block() will assume that
 * it needs to zero out portions of the start and/or end block.  If 2 AIO
 * threads are at work on the same unwritten block, they must be synchronized
 * or one thread will zero the other's data, causing corruption.
 */
static int
ext4_unaligned_aio(struct inode *inode, const struct iovec *iov,
                   unsigned long nr_segs, loff_t pos)
{
        struct super_block *sb = inode->i_sb;
        int blockmask = sb->s_blocksize - 1;
        size_t count = iov_length(iov, nr_segs);
        loff_t final_size = pos + count;

        if (pos >= inode->i_size)
                return 0;

        if ((pos & blockmask) || (final_size & blockmask))
                return 1;

        return 0;
}

static ssize_t
ext4_file_dio_write(struct kiocb *iocb, const struct iovec *iov,
                    unsigned long nr_segs, loff_t pos)
{
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_mapping->host;
        struct blk_plug plug;
        int unaligned_aio = 0;
        ssize_t ret;
        int overwrite = 0;
        size_t length = iov_length(iov, nr_segs);

        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
            !is_sync_kiocb(iocb))
                unaligned_aio = ext4_unaligned_aio(inode, iov, nr_segs, pos);

        /* Unaligned direct AIO must be serialized; see comment above */
        if (unaligned_aio) {
                static unsigned long unaligned_warn_time;

                /* Warn about this once per day */
                if (printk_timed_ratelimit(&unaligned_warn_time, 60*60*24*HZ))
                        ext4_msg(inode->i_sb, KERN_WARNING,
                                 "Unaligned AIO/DIO on inode %ld by %s; "
                                 "performance will be poor.",
                                 inode->i_ino, current->comm);
                mutex_lock(ext4_aio_mutex(inode));
                ext4_aiodio_wait(inode);
        }

        BUG_ON(iocb->ki_pos != pos);

        mutex_lock(&inode->i_mutex);
        blk_start_plug(&plug);

        iocb->private = &overwrite;

        /* check whether we do a DIO overwrite or not */
        if (ext4_should_dioread_nolock(inode) && !unaligned_aio &&
            !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
                struct ext4_map_blocks map;
                unsigned int blkbits = inode->i_blkbits;
                int err, len;

                map.m_lblk = pos >> blkbits;
                map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
                        - map.m_lblk;
                len = map.m_len;

                err = ext4_map_blocks(NULL, inode, &map, 0);
                /*
                 * 'err==len' means that all of blocks has been preallocated no
                 * matter they are initialized or not.  For excluding
                 * uninitialized extents, we need to check m_flags.  There are
                 * two conditions that indicate for initialized extents.
                 * 1) If we hit extent cache, EXT4_MAP_MAPPED flag is returned;
                 * 2) If we do a real lookup, non-flags are returned.
                 * So we should check these two conditions.
                 */
                if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
                        overwrite = 1;
        }

        ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
        mutex_unlock(&inode->i_mutex);

        if (ret > 0 || ret == -EIOCBQUEUED) {
                ssize_t err;

                err = generic_write_sync(file, pos, ret);
                if (err < 0 && ret > 0)
                        ret = err;
        }
        blk_finish_plug(&plug);

        if (unaligned_aio)
                mutex_unlock(ext4_aio_mutex(inode));

        return ret;
}

static ssize_t
ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
                unsigned long nr_segs, loff_t pos)
{
        struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
        ssize_t ret;

        /*
         * If we have encountered a bitmap-format file, the size limit
         * is smaller than s_maxbytes, which is for extent-mapped files.
         */

        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
                struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
                size_t length = iov_length(iov, nr_segs);

                if ((pos > sbi->s_bitmap_maxbytes ||
                    (pos == sbi->s_bitmap_maxbytes && length > 0)))
                        return -EFBIG;

                if (pos + length > sbi->s_bitmap_maxbytes) {
                        nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
                                              sbi->s_bitmap_maxbytes - pos);
                }
        }

        if (unlikely(iocb->ki_filp->f_flags & O_DIRECT))
                ret = ext4_file_dio_write(iocb, iov, nr_segs, pos);
        else
                ret = generic_file_aio_write(iocb, iov, nr_segs, pos);

        return ret;
}

static const struct vm_operations_struct ext4_file_vm_ops = {
        .fault          = filemap_fault,
        .page_mkwrite   = ext4_page_mkwrite,
};

static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
{
        struct address_space *mapping = file->f_mapping;

        if (!mapping->a_ops->readpage)
                return -ENOEXEC;
        file_accessed(file);
        vma->vm_ops = &ext4_file_vm_ops;
        vma->vm_flags |= VM_CAN_NONLINEAR;
        return 0;
}

static int ext4_file_open(struct inode * inode, struct file * filp)
{
        struct super_block *sb = inode->i_sb;
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        struct ext4_inode_info *ei = EXT4_I(inode);
        struct vfsmount *mnt = filp->f_path.mnt;
        struct path path;
        char buf[64], *cp;

        if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
                     !(sb->s_flags & MS_RDONLY))) {
                sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
                /*
                 * Sample where the filesystem has been mounted and
                 * store it in the superblock for sysadmin convenience
                 * when trying to sort through large numbers of block
                 * devices or filesystem images.
                 */
                memset(buf, 0, sizeof(buf));
                path.mnt = mnt;
                path.dentry = mnt->mnt_root;
                cp = d_path(&path, buf, sizeof(buf));
                if (!IS_ERR(cp)) {
                        handle_t *handle;
                        int err;

                        handle = ext4_journal_start_sb(sb, 1);
                        if (IS_ERR(handle))
                                return PTR_ERR(handle);
                        err = ext4_journal_get_write_access(handle, sbi->s_sbh);
                        if (err) {
                                ext4_journal_stop(handle);
                                return err;
                        }
                        strlcpy(sbi->s_es->s_last_mounted, cp,
                                sizeof(sbi->s_es->s_last_mounted));
                        ext4_handle_dirty_super(handle, sb);
                        ext4_journal_stop(handle);
                }
        }
        /*
         * Set up the jbd2_inode if we are opening the inode for
         * writing and the journal is present
         */
        if (sbi->s_journal && !ei->jinode && (filp->f_mode & FMODE_WRITE)) {
                struct jbd2_inode *jinode = jbd2_alloc_inode(GFP_KERNEL);

                spin_lock(&inode->i_lock);
                if (!ei->jinode) {
                        if (!jinode) {
                                spin_unlock(&inode->i_lock);
                                return -ENOMEM;
                        }
                        ei->jinode = jinode;
                        jbd2_journal_init_jbd_inode(ei->jinode, inode);
                        jinode = NULL;
                }
                spin_unlock(&inode->i_lock);
                if (unlikely(jinode != NULL))
                        jbd2_free_inode(jinode);
        }
        return dquot_file_open(inode, filp);
}

/*
 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 * by calling generic_file_llseek_size() with the appropriate maxbytes
 * value for each.
 */
loff_t ext4_llseek(struct file *file, loff_t offset, int origin)
{
        struct inode *inode = file->f_mapping->host;
        loff_t maxbytes;

        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
                maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
        else
                maxbytes = inode->i_sb->s_maxbytes;

        return generic_file_llseek_size(file, offset, origin,
                                        maxbytes, i_size_read(inode));
}

const struct file_operations ext4_file_operations = {
        .llseek         = ext4_llseek,
        .read           = do_sync_read,
        .write          = do_sync_write,
        .aio_read       = generic_file_aio_read,
        .aio_write      = ext4_file_write,
        .unlocked_ioctl = ext4_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = ext4_compat_ioctl,
#endif
        .mmap           = ext4_file_mmap,
        .open           = ext4_file_open,
        .release        = ext4_release_file,
        .fsync          = ext4_sync_file,
        .splice_read    = generic_file_splice_read,
        .splice_write   = generic_file_splice_write,
        .fallocate      = ext4_fallocate,
};

const struct inode_operations ext4_file_inode_operations = {
        .setattr        = ext4_setattr,
        .getattr        = ext4_getattr,
#ifdef CONFIG_EXT4_FS_XATTR
        .setxattr       = generic_setxattr,
        .getxattr       = generic_getxattr,
        .listxattr      = ext4_listxattr,
        .removexattr    = generic_removexattr,
#endif
        .get_acl        = ext4_get_acl,
        .fiemap         = ext4_fiemap,
};