--- /dev/null
+/*
+ * 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/mount.h>
+#include <linux/path.h>
+#include <linux/quotaops.h>
+#include <linux/pagevec.h>
+#include <linux/uio.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_unwritten_wait(struct inode *inode)
+{
+ wait_queue_head_t *wq = ext4_ioend_wq(inode);
+
+ wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_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, struct iov_iter *from, loff_t pos)
+{
+ struct super_block *sb = inode->i_sb;
+ int blockmask = sb->s_blocksize - 1;
+
+ if (pos >= i_size_read(inode))
+ return 0;
+
+ if ((pos | iov_iter_alignment(from)) & blockmask)
+ return 1;
+
+ return 0;
+}
+
+static ssize_t
+ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file_inode(iocb->ki_filp);
+ struct mutex *aio_mutex = NULL;
+ struct blk_plug plug;
+ int o_direct = iocb->ki_flags & IOCB_DIRECT;
+ int overwrite = 0;
+ ssize_t ret;
+
+ /*
+ * Unaligned direct AIO must be serialized; see comment above
+ * In the case of O_APPEND, assume that we must always serialize
+ */
+ if (o_direct &&
+ ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
+ !is_sync_kiocb(iocb) &&
+ (iocb->ki_flags & IOCB_APPEND ||
+ ext4_unaligned_aio(inode, from, iocb->ki_pos))) {
+ aio_mutex = ext4_aio_mutex(inode);
+ mutex_lock(aio_mutex);
+ ext4_unwritten_wait(inode);
+ }
+
+ mutex_lock(&inode->i_mutex);
+ ret = generic_write_checks(iocb, from);
+ if (ret <= 0)
+ goto out;
+
+ /*
+ * 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);
+
+ if (iocb->ki_pos >= sbi->s_bitmap_maxbytes) {
+ ret = -EFBIG;
+ goto out;
+ }
+ iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
+ }
+
+ iocb->private = &overwrite;
+ if (o_direct) {
+ size_t length = iov_iter_count(from);
+ loff_t pos = iocb->ki_pos;
+ blk_start_plug(&plug);
+
+ /* check whether we do a DIO overwrite or not */
+ if (ext4_should_dioread_nolock(inode) && !aio_mutex &&
+ !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
+ * unwritten 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_write_iter(iocb, from);
+ mutex_unlock(&inode->i_mutex);
+
+ if (ret > 0) {
+ ssize_t err;
+
+ err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+ if (err < 0)
+ ret = err;
+ }
+ if (o_direct)
+ blk_finish_plug(&plug);
+
+ if (aio_mutex)
+ mutex_unlock(aio_mutex);
+ return ret;
+
+out:
+ mutex_unlock(&inode->i_mutex);
+ if (aio_mutex)
+ mutex_unlock(aio_mutex);
+ return ret;
+}
+
+#ifdef CONFIG_FS_DAX
+static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ return dax_fault(vma, vmf, ext4_get_block);
+ /* Is this the right get_block? */
+}
+
+static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ return dax_mkwrite(vma, vmf, ext4_get_block);
+}
+
+static const struct vm_operations_struct ext4_dax_vm_ops = {
+ .fault = ext4_dax_fault,
+ .page_mkwrite = ext4_dax_mkwrite,
+ .pfn_mkwrite = dax_pfn_mkwrite,
+};
+#else
+#define ext4_dax_vm_ops ext4_file_vm_ops
+#endif
+
+static const struct vm_operations_struct ext4_file_vm_ops = {
+ .fault = filemap_fault,
+ .map_pages = filemap_map_pages,
+ .page_mkwrite = ext4_page_mkwrite,
+};
+
+static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ struct inode *inode = file->f_mapping->host;
+
+ if (ext4_encrypted_inode(inode)) {
+ int err = ext4_generate_encryption_key(inode);
+ if (err)
+ return 0;
+ }
+ file_accessed(file);
+ if (IS_DAX(file_inode(file))) {
+ vma->vm_ops = &ext4_dax_vm_ops;
+ vma->vm_flags |= VM_MIXEDMAP;
+ } else {
+ vma->vm_ops = &ext4_file_vm_ops;
+ }
+ 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 vfsmount *mnt = filp->f_path.mnt;
+ struct path path;
+ char buf[64], *cp;
+ int ret;
+
+ 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, EXT4_HT_MISC, 1);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+ BUFFER_TRACE(sbi->s_sbh, "get_write_access");
+ 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 (filp->f_mode & FMODE_WRITE) {
+ ret = ext4_inode_attach_jinode(inode);
+ if (ret < 0)
+ return ret;
+ }
+ ret = dquot_file_open(inode, filp);
+ if (!ret && ext4_encrypted_inode(inode)) {
+ ret = ext4_generate_encryption_key(inode);
+ if (ret)
+ ret = -EACCES;
+ }
+ return ret;
+}
+
+/*
+ * Here we use ext4_map_blocks() to get a block mapping for a extent-based
+ * file rather than ext4_ext_walk_space() because we can introduce
+ * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
+ * function. When extent status tree has been fully implemented, it will
+ * track all extent status for a file and we can directly use it to
+ * retrieve the offset for SEEK_DATA/SEEK_HOLE.
+ */
+
+/*
+ * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
+ * lookup page cache to check whether or not there has some data between
+ * [startoff, endoff] because, if this range contains an unwritten extent,
+ * we determine this extent as a data or a hole according to whether the
+ * page cache has data or not.
+ */
+static int ext4_find_unwritten_pgoff(struct inode *inode,
+ int whence,
+ struct ext4_map_blocks *map,
+ loff_t *offset)
+{
+ struct pagevec pvec;
+ unsigned int blkbits;
+ pgoff_t index;
+ pgoff_t end;
+ loff_t endoff;
+ loff_t startoff;
+ loff_t lastoff;
+ int found = 0;
+
+ blkbits = inode->i_sb->s_blocksize_bits;
+ startoff = *offset;
+ lastoff = startoff;
+ endoff = (loff_t)(map->m_lblk + map->m_len) << blkbits;
+
+ index = startoff >> PAGE_CACHE_SHIFT;
+ end = endoff >> PAGE_CACHE_SHIFT;
+
+ pagevec_init(&pvec, 0);
+ do {
+ int i, num;
+ unsigned long nr_pages;
+
+ num = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
+ nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
+ (pgoff_t)num);
+ if (nr_pages == 0) {
+ if (whence == SEEK_DATA)
+ break;
+
+ BUG_ON(whence != SEEK_HOLE);
+ /*
+ * If this is the first time to go into the loop and
+ * offset is not beyond the end offset, it will be a
+ * hole at this offset
+ */
+ if (lastoff == startoff || lastoff < endoff)
+ found = 1;
+ break;
+ }
+
+ /*
+ * If this is the first time to go into the loop and
+ * offset is smaller than the first page offset, it will be a
+ * hole at this offset.
+ */
+ if (lastoff == startoff && whence == SEEK_HOLE &&
+ lastoff < page_offset(pvec.pages[0])) {
+ found = 1;
+ break;
+ }
+
+ for (i = 0; i < nr_pages; i++) {
+ struct page *page = pvec.pages[i];
+ struct buffer_head *bh, *head;
+
+ /*
+ * If the current offset is not beyond the end of given
+ * range, it will be a hole.
+ */
+ if (lastoff < endoff && whence == SEEK_HOLE &&
+ page->index > end) {
+ found = 1;
+ *offset = lastoff;
+ goto out;
+ }
+
+ lock_page(page);
+
+ if (unlikely(page->mapping != inode->i_mapping)) {
+ unlock_page(page);
+ continue;
+ }
+
+ if (!page_has_buffers(page)) {
+ unlock_page(page);
+ continue;
+ }
+
+ if (page_has_buffers(page)) {
+ lastoff = page_offset(page);
+ bh = head = page_buffers(page);
+ do {
+ if (buffer_uptodate(bh) ||
+ buffer_unwritten(bh)) {
+ if (whence == SEEK_DATA)
+ found = 1;
+ } else {
+ if (whence == SEEK_HOLE)
+ found = 1;
+ }
+ if (found) {
+ *offset = max_t(loff_t,
+ startoff, lastoff);
+ unlock_page(page);
+ goto out;
+ }
+ lastoff += bh->b_size;
+ bh = bh->b_this_page;
+ } while (bh != head);
+ }
+
+ lastoff = page_offset(page) + PAGE_SIZE;
+ unlock_page(page);
+ }
+
+ /*
+ * The no. of pages is less than our desired, that would be a
+ * hole in there.
+ */
+ if (nr_pages < num && whence == SEEK_HOLE) {
+ found = 1;
+ *offset = lastoff;
+ break;
+ }
+
+ index = pvec.pages[i - 1]->index + 1;
+ pagevec_release(&pvec);
+ } while (index <= end);
+
+out:
+ pagevec_release(&pvec);
+ return found;
+}
+
+/*
+ * ext4_seek_data() retrieves the offset for SEEK_DATA.
+ */
+static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
+{
+ struct inode *inode = file->f_mapping->host;
+ struct ext4_map_blocks map;
+ struct extent_status es;
+ ext4_lblk_t start, last, end;
+ loff_t dataoff, isize;
+ int blkbits;
+ int ret = 0;
+
+ mutex_lock(&inode->i_mutex);
+
+ isize = i_size_read(inode);
+ if (offset >= isize) {
+ mutex_unlock(&inode->i_mutex);
+ return -ENXIO;
+ }
+
+ blkbits = inode->i_sb->s_blocksize_bits;
+ start = offset >> blkbits;
+ last = start;
+ end = isize >> blkbits;
+ dataoff = offset;
+
+ do {
+ map.m_lblk = last;
+ map.m_len = end - last + 1;
+ ret = ext4_map_blocks(NULL, inode, &map, 0);
+ if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
+ if (last != start)
+ dataoff = (loff_t)last << blkbits;
+ break;
+ }
+
+ /*
+ * If there is a delay extent at this offset,
+ * it will be as a data.
+ */
+ ext4_es_find_delayed_extent_range(inode, last, last, &es);
+ if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
+ if (last != start)
+ dataoff = (loff_t)last << blkbits;
+ break;
+ }
+
+ /*
+ * If there is a unwritten extent at this offset,
+ * it will be as a data or a hole according to page
+ * cache that has data or not.
+ */
+ if (map.m_flags & EXT4_MAP_UNWRITTEN) {
+ int unwritten;
+ unwritten = ext4_find_unwritten_pgoff(inode, SEEK_DATA,
+ &map, &dataoff);
+ if (unwritten)
+ break;
+ }
+
+ last++;
+ dataoff = (loff_t)last << blkbits;
+ } while (last <= end);
+
+ mutex_unlock(&inode->i_mutex);
+
+ if (dataoff > isize)
+ return -ENXIO;
+
+ return vfs_setpos(file, dataoff, maxsize);
+}
+
+/*
+ * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
+ */
+static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
+{
+ struct inode *inode = file->f_mapping->host;
+ struct ext4_map_blocks map;
+ struct extent_status es;
+ ext4_lblk_t start, last, end;
+ loff_t holeoff, isize;
+ int blkbits;
+ int ret = 0;
+
+ mutex_lock(&inode->i_mutex);
+
+ isize = i_size_read(inode);
+ if (offset >= isize) {
+ mutex_unlock(&inode->i_mutex);
+ return -ENXIO;
+ }
+
+ blkbits = inode->i_sb->s_blocksize_bits;
+ start = offset >> blkbits;
+ last = start;
+ end = isize >> blkbits;
+ holeoff = offset;
+
+ do {
+ map.m_lblk = last;
+ map.m_len = end - last + 1;
+ ret = ext4_map_blocks(NULL, inode, &map, 0);
+ if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
+ last += ret;
+ holeoff = (loff_t)last << blkbits;
+ continue;
+ }
+
+ /*
+ * If there is a delay extent at this offset,
+ * we will skip this extent.
+ */
+ ext4_es_find_delayed_extent_range(inode, last, last, &es);
+ if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
+ last = es.es_lblk + es.es_len;
+ holeoff = (loff_t)last << blkbits;
+ continue;
+ }
+
+ /*
+ * If there is a unwritten extent at this offset,
+ * it will be as a data or a hole according to page
+ * cache that has data or not.
+ */
+ if (map.m_flags & EXT4_MAP_UNWRITTEN) {
+ int unwritten;
+ unwritten = ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
+ &map, &holeoff);
+ if (!unwritten) {
+ last += ret;
+ holeoff = (loff_t)last << blkbits;
+ continue;
+ }
+ }
+
+ /* find a hole */
+ break;
+ } while (last <= end);
+
+ mutex_unlock(&inode->i_mutex);
+
+ if (holeoff > isize)
+ holeoff = isize;
+
+ return vfs_setpos(file, holeoff, maxsize);
+}
+
+/*
+ * 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 whence)
+{
+ 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;
+
+ switch (whence) {
+ case SEEK_SET:
+ case SEEK_CUR:
+ case SEEK_END:
+ return generic_file_llseek_size(file, offset, whence,
+ maxbytes, i_size_read(inode));
+ case SEEK_DATA:
+ return ext4_seek_data(file, offset, maxbytes);
+ case SEEK_HOLE:
+ return ext4_seek_hole(file, offset, maxbytes);
+ }
+
+ return -EINVAL;
+}
+
+const struct file_operations ext4_file_operations = {
+ .llseek = ext4_llseek,
+ .read_iter = generic_file_read_iter,
+ .write_iter = ext4_file_write_iter,
+ .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 = iter_file_splice_write,
+ .fallocate = ext4_fallocate,
+};
+
+const struct inode_operations ext4_file_inode_operations = {
+ .setattr = ext4_setattr,
+ .getattr = ext4_getattr,
+ .setxattr = generic_setxattr,
+ .getxattr = generic_getxattr,
+ .listxattr = ext4_listxattr,
+ .removexattr = generic_removexattr,
+ .get_acl = ext4_get_acl,
+ .set_acl = ext4_set_acl,
+ .fiemap = ext4_fiemap,
+};
+
Code Review / kvmfornfv.git / blobdiff