blob: c0d59d91bc68a3ccd8b5fee610fc6d6eb8505bda [file] [log] [blame]
// 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/mount.h>
#include <linux/path.h>
#include <linux/dax.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"
#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 >= ALIGN(i_size_read(inode), sb->s_blocksize))
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);
/*
* Unaligned direct AIO must be the only IO in flight. Otherwise
* overlapping aligned IO after unaligned might result in data
* corruption.
*/
if (ret == -EIOCBQUEUED && unaligned_aio)
ext4_unwritten_wait(inode);
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 int ext4_dax_huge_fault(struct vm_fault *vmf,
enum page_entry_size pe_size)
{
int result;
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);
if (write) {
sb_start_pagefault(sb);
file_update_time(vmf->vma->vm_file);
down_read(&EXT4_I(inode)->i_mmap_sem);
handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
EXT4_DATA_TRANS_BLOCKS(sb));
} else {
down_read(&EXT4_I(inode)->i_mmap_sem);
}
if (!IS_ERR(handle))
result = dax_iomap_fault(vmf, pe_size, &ext4_iomap_ops);
else
result = VM_FAULT_SIGBUS;
if (write) {
if (!IS_ERR(handle))
ext4_journal_stop(handle);
up_read(&EXT4_I(inode)->i_mmap_sem);
sb_end_pagefault(sb);
} else {
up_read(&EXT4_I(inode)->i_mmap_sem);
}
return result;
}
static int 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;
file_accessed(file);
if (IS_DAX(file_inode(file))) {
vma->vm_ops = &ext4_dax_vm_ops;
vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
} 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(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
return -EIO;
if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
!sb_rdonly(sb))) {
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);
}
}
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);
}
/*
* 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,
ext4_lblk_t end_blk,
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)end_blk << blkbits;
index = startoff >> PAGE_SHIFT;
end = (endoff - 1) >> PAGE_SHIFT;
pagevec_init(&pvec, 0);
do {
int i;
unsigned long nr_pages;
nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping,
&index, end);
if (nr_pages == 0)
break;
for (i = 0; i < nr_pages; i++) {
struct page *page = pvec.pages[i];
struct buffer_head *bh, *head;
/*
* If current offset is smaller than the page offset,
* there is a hole at this offset.
*/
if (whence == SEEK_HOLE && lastoff < endoff &&
lastoff < page_offset(pvec.pages[i])) {
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 (lastoff + bh->b_size <= startoff)
goto next;
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;
}
next:
lastoff += bh->b_size;
bh = bh->b_this_page;
} while (bh != head);
}
lastoff = page_offset(page) + PAGE_SIZE;
unlock_page(page);
}
pagevec_release(&pvec);
} while (index <= end);
/* There are no pages upto endoff - that would be a hole in there. */
if (whence == SEEK_HOLE && lastoff < endoff) {
found = 1;
*offset = lastoff;
}
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 extent_status es;
ext4_lblk_t start, last, end;
loff_t dataoff, isize;
int blkbits;
int ret;
inode_lock(inode);
isize = i_size_read(inode);
if (offset < 0 || offset >= isize) {
inode_unlock(inode);
return -ENXIO;
}
blkbits = inode->i_sb->s_blocksize_bits;
start = offset >> blkbits;
last = start;
end = isize >> blkbits;
dataoff = offset;
do {
ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
if (ret <= 0) {
/* No extent found -> no data */
if (ret == 0)
ret = -ENXIO;
inode_unlock(inode);
return ret;
}
last = es.es_lblk;
if (last != start)
dataoff = (loff_t)last << blkbits;
if (!ext4_es_is_unwritten(&es))
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 (ext4_find_unwritten_pgoff(inode, SEEK_DATA,
es.es_lblk + es.es_len, &dataoff))
break;
last += es.es_len;
dataoff = (loff_t)last << blkbits;
cond_resched();
} while (last <= end);
inode_unlock(inode);
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 extent_status es;
ext4_lblk_t start, last, end;
loff_t holeoff, isize;
int blkbits;
int ret;
inode_lock(inode);
isize = i_size_read(inode);
if (offset < 0 || offset >= isize) {
inode_unlock(inode);
return -ENXIO;
}
blkbits = inode->i_sb->s_blocksize_bits;
start = offset >> blkbits;
last = start;
end = isize >> blkbits;
holeoff = offset;
do {
ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
if (ret < 0) {
inode_unlock(inode);
return ret;
}
/* Found a hole? */
if (ret == 0 || es.es_lblk > last) {
if (last != start)
holeoff = (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 (ext4_es_is_unwritten(&es) &&
ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
last + es.es_len, &holeoff))
break;
last += es.es_len;
holeoff = (loff_t)last << blkbits;
cond_resched();
} while (last <= end);
inode_unlock(inode);
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 = 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,
.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,
};