v4.19.13 snapshot.
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
new file mode 100644
index 0000000..69d65d4
--- /dev/null
+++ b/fs/ext4/file.c
@@ -0,0 +1,524 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/iomap.h>
+#include <linux/mount.h>
+#include <linux/path.h>
+#include <linux/dax.h>
+#include <linux/quotaops.h>
+#include <linux/pagevec.h>
+#include <linux/uio.h>
+#include <linux/mman.h>
+#include "ext4.h"
+#include "ext4_jbd2.h"
+#include "xattr.h"
+#include "acl.h"
+
+#ifdef CONFIG_FS_DAX
+static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ ssize_t ret;
+
+ if (!inode_trylock_shared(inode)) {
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EAGAIN;
+ inode_lock_shared(inode);
+ }
+ /*
+ * Recheck under inode lock - at this point we are sure it cannot
+ * change anymore
+ */
+ if (!IS_DAX(inode)) {
+ inode_unlock_shared(inode);
+ /* Fallback to buffered IO in case we cannot support DAX */
+ return generic_file_read_iter(iocb, to);
+ }
+ ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
+ inode_unlock_shared(inode);
+
+ file_accessed(iocb->ki_filp);
+ return ret;
+}
+#endif
+
+static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ if (unlikely(ext4_forced_shutdown(EXT4_SB(file_inode(iocb->ki_filp)->i_sb))))
+ return -EIO;
+
+ if (!iov_iter_count(to))
+ return 0; /* skip atime */
+
+#ifdef CONFIG_FS_DAX
+ if (IS_DAX(file_inode(iocb->ki_filp)))
+ return ext4_dax_read_iter(iocb, to);
+#endif
+ return generic_file_read_iter(iocb, to);
+}
+
+/*
+ * 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;
+}
+
+/* Is IO overwriting allocated and initialized blocks? */
+static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
+{
+ struct ext4_map_blocks map;
+ unsigned int blkbits = inode->i_blkbits;
+ int err, blklen;
+
+ if (pos + len > i_size_read(inode))
+ return false;
+
+ map.m_lblk = pos >> blkbits;
+ map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
+ blklen = map.m_len;
+
+ err = ext4_map_blocks(NULL, inode, &map, 0);
+ /*
+ * 'err==len' means that all of the blocks have been preallocated,
+ * regardless of whether they have been initialized or not. To exclude
+ * unwritten extents, we need to check m_flags.
+ */
+ return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
+}
+
+static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ ssize_t ret;
+
+ ret = generic_write_checks(iocb, from);
+ if (ret <= 0)
+ return 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);
+
+ if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
+ return -EFBIG;
+ iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
+ }
+ return iov_iter_count(from);
+}
+
+#ifdef CONFIG_FS_DAX
+static ssize_t
+ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ ssize_t ret;
+
+ if (!inode_trylock(inode)) {
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EAGAIN;
+ inode_lock(inode);
+ }
+ ret = ext4_write_checks(iocb, from);
+ if (ret <= 0)
+ goto out;
+ ret = file_remove_privs(iocb->ki_filp);
+ if (ret)
+ goto out;
+ ret = file_update_time(iocb->ki_filp);
+ if (ret)
+ goto out;
+
+ ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
+out:
+ inode_unlock(inode);
+ if (ret > 0)
+ ret = generic_write_sync(iocb, ret);
+ return ret;
+}
+#endif
+
+static ssize_t
+ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ int o_direct = iocb->ki_flags & IOCB_DIRECT;
+ int unaligned_aio = 0;
+ int overwrite = 0;
+ ssize_t ret;
+
+ if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+ return -EIO;
+
+#ifdef CONFIG_FS_DAX
+ if (IS_DAX(inode))
+ return ext4_dax_write_iter(iocb, from);
+#endif
+ if (!o_direct && (iocb->ki_flags & IOCB_NOWAIT))
+ return -EOPNOTSUPP;
+
+ if (!inode_trylock(inode)) {
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EAGAIN;
+ inode_lock(inode);
+ }
+
+ ret = ext4_write_checks(iocb, from);
+ if (ret <= 0)
+ goto out;
+
+ /*
+ * Unaligned direct AIO must be serialized among each other as zeroing
+ * of partial blocks of two competing unaligned AIOs can result in data
+ * corruption.
+ */
+ if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
+ !is_sync_kiocb(iocb) &&
+ ext4_unaligned_aio(inode, from, iocb->ki_pos)) {
+ unaligned_aio = 1;
+ ext4_unwritten_wait(inode);
+ }
+
+ iocb->private = &overwrite;
+ /* Check whether we do a DIO overwrite or not */
+ if (o_direct && !unaligned_aio) {
+ if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {
+ if (ext4_should_dioread_nolock(inode))
+ overwrite = 1;
+ } else if (iocb->ki_flags & IOCB_NOWAIT) {
+ ret = -EAGAIN;
+ goto out;
+ }
+ }
+
+ ret = __generic_file_write_iter(iocb, from);
+ inode_unlock(inode);
+
+ if (ret > 0)
+ ret = generic_write_sync(iocb, ret);
+
+ return ret;
+
+out:
+ inode_unlock(inode);
+ return ret;
+}
+
+#ifdef CONFIG_FS_DAX
+static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
+ enum page_entry_size pe_size)
+{
+ int error = 0;
+ vm_fault_t result;
+ int retries = 0;
+ handle_t *handle = NULL;
+ struct inode *inode = file_inode(vmf->vma->vm_file);
+ struct super_block *sb = inode->i_sb;
+
+ /*
+ * We have to distinguish real writes from writes which will result in a
+ * COW page; COW writes should *not* poke the journal (the file will not
+ * be changed). Doing so would cause unintended failures when mounted
+ * read-only.
+ *
+ * We check for VM_SHARED rather than vmf->cow_page since the latter is
+ * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
+ * other sizes, dax_iomap_fault will handle splitting / fallback so that
+ * we eventually come back with a COW page.
+ */
+ bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
+ (vmf->vma->vm_flags & VM_SHARED);
+ pfn_t pfn;
+
+ if (write) {
+ sb_start_pagefault(sb);
+ file_update_time(vmf->vma->vm_file);
+ down_read(&EXT4_I(inode)->i_mmap_sem);
+retry:
+ handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
+ EXT4_DATA_TRANS_BLOCKS(sb));
+ if (IS_ERR(handle)) {
+ up_read(&EXT4_I(inode)->i_mmap_sem);
+ sb_end_pagefault(sb);
+ return VM_FAULT_SIGBUS;
+ }
+ } else {
+ down_read(&EXT4_I(inode)->i_mmap_sem);
+ }
+ result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
+ if (write) {
+ ext4_journal_stop(handle);
+
+ if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
+ ext4_should_retry_alloc(sb, &retries))
+ goto retry;
+ /* Handling synchronous page fault? */
+ if (result & VM_FAULT_NEEDDSYNC)
+ result = dax_finish_sync_fault(vmf, pe_size, pfn);
+ up_read(&EXT4_I(inode)->i_mmap_sem);
+ sb_end_pagefault(sb);
+ } else {
+ up_read(&EXT4_I(inode)->i_mmap_sem);
+ }
+
+ return result;
+}
+
+static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
+{
+ return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
+}
+
+static const struct vm_operations_struct ext4_dax_vm_ops = {
+ .fault = ext4_dax_fault,
+ .huge_fault = ext4_dax_huge_fault,
+ .page_mkwrite = ext4_dax_fault,
+ .pfn_mkwrite = ext4_dax_fault,
+};
+#else
+#define ext4_dax_vm_ops ext4_file_vm_ops
+#endif
+
+static const struct vm_operations_struct ext4_file_vm_ops = {
+ .fault = ext4_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 (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+ return -EIO;
+
+ /*
+ * We don't support synchronous mappings for non-DAX files. At least
+ * until someone comes with a sensible use case.
+ */
+ if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC))
+ return -EOPNOTSUPP;
+
+ file_accessed(file);
+ if (IS_DAX(file_inode(file))) {
+ vma->vm_ops = &ext4_dax_vm_ops;
+ vma->vm_flags |= VM_HUGEPAGE;
+ } else {
+ vma->vm_ops = &ext4_file_vm_ops;
+ }
+ return 0;
+}
+
+static int ext4_sample_last_mounted(struct super_block *sb,
+ struct vfsmount *mnt)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ struct path path;
+ char buf[64], *cp;
+ handle_t *handle;
+ int err;
+
+ if (likely(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED))
+ return 0;
+
+ if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
+ return 0;
+
+ 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));
+ err = 0;
+ if (IS_ERR(cp))
+ goto out;
+
+ handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
+ err = PTR_ERR(handle);
+ if (IS_ERR(handle))
+ goto out;
+ BUFFER_TRACE(sbi->s_sbh, "get_write_access");
+ err = ext4_journal_get_write_access(handle, sbi->s_sbh);
+ if (err)
+ goto out_journal;
+ strlcpy(sbi->s_es->s_last_mounted, cp,
+ sizeof(sbi->s_es->s_last_mounted));
+ ext4_handle_dirty_super(handle, sb);
+out_journal:
+ ext4_journal_stop(handle);
+out:
+ sb_end_intwrite(sb);
+ return err;
+}
+
+static int ext4_file_open(struct inode * inode, struct file * filp)
+{
+ int ret;
+
+ if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+ return -EIO;
+
+ ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
+ if (ret)
+ return ret;
+
+ ret = fscrypt_file_open(inode, filp);
+ if (ret)
+ return ret;
+
+ /*
+ * 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;
+ }
+
+ filp->f_mode |= FMODE_NOWAIT;
+ 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 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) {
+ default:
+ return generic_file_llseek_size(file, offset, whence,
+ maxbytes, i_size_read(inode));
+ case SEEK_HOLE:
+ inode_lock_shared(inode);
+ offset = iomap_seek_hole(inode, offset, &ext4_iomap_ops);
+ inode_unlock_shared(inode);
+ break;
+ case SEEK_DATA:
+ inode_lock_shared(inode);
+ offset = iomap_seek_data(inode, offset, &ext4_iomap_ops);
+ inode_unlock_shared(inode);
+ break;
+ }
+
+ if (offset < 0)
+ return offset;
+ return vfs_setpos(file, offset, maxbytes);
+}
+
+const struct file_operations ext4_file_operations = {
+ .llseek = ext4_llseek,
+ .read_iter = ext4_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,
+ .mmap_supported_flags = MAP_SYNC,
+ .open = ext4_file_open,
+ .release = ext4_release_file,
+ .fsync = ext4_sync_file,
+ .get_unmapped_area = thp_get_unmapped_area,
+ .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_file_getattr,
+ .listxattr = ext4_listxattr,
+ .get_acl = ext4_get_acl,
+ .set_acl = ext4_set_acl,
+ .fiemap = ext4_fiemap,
+};
+