linux/fs/ext4/file.c
Linus Torvalds 93061f390f These changes contains a fix for overlayfs interacting with some
(badly behaved) dentry code in various file systems.  These have been
 reviewed by Al and the respective file system mtinainers and are going
 through the ext4 tree for convenience.
 
 This also has a few ext4 encryption bug fixes that were discovered in
 Android testing (yes, we will need to get these sync'ed up with the
 fs/crypto code; I'll take care of that).  It also has some bug fixes
 and a change to ignore the legacy quota options to allow for xfstests
 regression testing of ext4's internal quota feature and to be more
 consistent with how xfs handles this case.
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Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 bugfixes from Ted Ts'o:
 "These changes contains a fix for overlayfs interacting with some
  (badly behaved) dentry code in various file systems.  These have been
  reviewed by Al and the respective file system mtinainers and are going
  through the ext4 tree for convenience.

  This also has a few ext4 encryption bug fixes that were discovered in
  Android testing (yes, we will need to get these sync'ed up with the
  fs/crypto code; I'll take care of that).  It also has some bug fixes
  and a change to ignore the legacy quota options to allow for xfstests
  regression testing of ext4's internal quota feature and to be more
  consistent with how xfs handles this case"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: ignore quota mount options if the quota feature is enabled
  ext4 crypto: fix some error handling
  ext4: avoid calling dquot_get_next_id() if quota is not enabled
  ext4: retry block allocation for failed DIO and DAX writes
  ext4: add lockdep annotations for i_data_sem
  ext4: allow readdir()'s of large empty directories to be interrupted
  btrfs: fix crash/invalid memory access on fsync when using overlayfs
  ext4 crypto: use dget_parent() in ext4_d_revalidate()
  ext4: use file_dentry()
  ext4: use dget_parent() in ext4_file_open()
  nfs: use file_dentry()
  fs: add file_dentry()
  ext4 crypto: don't let data integrity writebacks fail with ENOMEM
  ext4: check if in-inode xattr is corrupted in ext4_expand_extra_isize_ea()
2016-04-07 17:22:20 -07:00

728 lines
18 KiB
C

/*
* 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"
/*
* 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 blk_plug plug;
int o_direct = iocb->ki_flags & IOCB_DIRECT;
int unaligned_aio = 0;
int overwrite = 0;
ssize_t ret;
inode_lock(inode);
ret = generic_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);
}
/*
* 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) && !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
* 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);
inode_unlock(inode);
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);
return ret;
out:
inode_unlock(inode);
return ret;
}
#ifdef CONFIG_FS_DAX
static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
int result;
handle_t *handle = NULL;
struct inode *inode = file_inode(vma->vm_file);
struct super_block *sb = inode->i_sb;
bool write = vmf->flags & FAULT_FLAG_WRITE;
if (write) {
sb_start_pagefault(sb);
file_update_time(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 = VM_FAULT_SIGBUS;
else
result = __dax_fault(vma, vmf, ext4_dax_mmap_get_block, NULL);
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_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
pmd_t *pmd, unsigned int flags)
{
int result;
handle_t *handle = NULL;
struct inode *inode = file_inode(vma->vm_file);
struct super_block *sb = inode->i_sb;
bool write = flags & FAULT_FLAG_WRITE;
if (write) {
sb_start_pagefault(sb);
file_update_time(vma->vm_file);
down_read(&EXT4_I(inode)->i_mmap_sem);
handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
ext4_chunk_trans_blocks(inode,
PMD_SIZE / PAGE_SIZE));
} else
down_read(&EXT4_I(inode)->i_mmap_sem);
if (IS_ERR(handle))
result = VM_FAULT_SIGBUS;
else
result = __dax_pmd_fault(vma, addr, pmd, flags,
ext4_dax_mmap_get_block, NULL);
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;
}
/*
* Handle write fault for VM_MIXEDMAP mappings. Similarly to ext4_dax_fault()
* handler we check for races agaist truncate. Note that since we cycle through
* i_mmap_sem, we are sure that also any hole punching that began before we
* were called is finished by now and so if it included part of the file we
* are working on, our pte will get unmapped and the check for pte_same() in
* wp_pfn_shared() fails. Thus fault gets retried and things work out as
* desired.
*/
static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma,
struct vm_fault *vmf)
{
struct inode *inode = file_inode(vma->vm_file);
struct super_block *sb = inode->i_sb;
loff_t size;
int ret;
sb_start_pagefault(sb);
file_update_time(vma->vm_file);
down_read(&EXT4_I(inode)->i_mmap_sem);
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (vmf->pgoff >= size)
ret = VM_FAULT_SIGBUS;
else
ret = dax_pfn_mkwrite(vma, vmf);
up_read(&EXT4_I(inode)->i_mmap_sem);
sb_end_pagefault(sb);
return ret;
}
static const struct vm_operations_struct ext4_dax_vm_ops = {
.fault = ext4_dax_fault,
.pmd_fault = ext4_dax_pmd_fault,
.page_mkwrite = ext4_dax_fault,
.pfn_mkwrite = ext4_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 = 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 (ext4_encrypted_inode(inode)) {
int err = ext4_get_encryption_info(inode);
if (err)
return 0;
if (ext4_encryption_info(inode) == NULL)
return -ENOKEY;
}
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 dentry *dir;
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);
}
}
if (ext4_encrypted_inode(inode)) {
ret = ext4_get_encryption_info(inode);
if (ret)
return -EACCES;
if (ext4_encryption_info(inode) == NULL)
return -ENOKEY;
}
dir = dget_parent(file_dentry(filp));
if (ext4_encrypted_inode(d_inode(dir)) &&
!ext4_is_child_context_consistent_with_parent(d_inode(dir), inode)) {
ext4_warning(inode->i_sb,
"Inconsistent encryption contexts: %lu/%lu\n",
(unsigned long) d_inode(dir)->i_ino,
(unsigned long) inode->i_ino);
dput(dir);
return -EPERM;
}
dput(dir);
/*
* 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;
}
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 >> PAGE_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 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 >= 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 >= 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 = 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,
};