linux-stable/fs/xfs/xfs_file.c
Dave Chinner 36f11775da xfs: properly serialise fallocate against AIO+DIO
[ Upstream commit 249bd9087a ]

AIO+DIO can extend the file size on IO completion, and it holds
no inode locks while the IO is in flight. Therefore, a race
condition exists in file size updates if we do something like this:

aio-thread			fallocate-thread

lock inode
submit IO beyond inode->i_size
unlock inode
.....
				lock inode
				break layouts
				if (off + len > inode->i_size)
					new_size = off + len
				.....
				inode_dio_wait()
				<blocks>
.....
completes
inode->i_size updated
inode_dio_done()
....
				<wakes>
				<does stuff no long beyond EOF>
				if (new_size)
					xfs_vn_setattr(inode, new_size)

Yup, that attempt to extend the file size in the fallocate code
turns into a truncate - it removes the whatever the aio write
allocated and put to disk, and reduced the inode size back down to
where the fallocate operation ends.

Fundamentally, xfs_file_fallocate()  not compatible with racing
AIO+DIO completions, so we need to move the inode_dio_wait() call
up to where the lock the inode and break the layouts.

Secondly, storing the inode size and then using it unchecked without
holding the ILOCK is not safe; we can only do such a thing if we've
locked out and drained all IO and other modification operations,
which we don't do initially in xfs_file_fallocate.

It should be noted that some of the fallocate operations are
compound operations - they are made up of multiple manipulations
that may zero data, and so we may need to flush and invalidate the
file multiple times during an operation. However, we only need to
lock out IO and other space manipulation operations once, as that
lockout is maintained until the entire fallocate operation has been
completed.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01 13:17:14 +02:00

1318 lines
34 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2005 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_inode_item.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_dir2.h"
#include "xfs_dir2_priv.h"
#include "xfs_ioctl.h"
#include "xfs_trace.h"
#include "xfs_log.h"
#include "xfs_icache.h"
#include "xfs_pnfs.h"
#include "xfs_iomap.h"
#include "xfs_reflink.h"
#include <linux/falloc.h>
#include <linux/backing-dev.h>
#include <linux/mman.h>
#include <linux/fadvise.h>
static const struct vm_operations_struct xfs_file_vm_ops;
int
xfs_update_prealloc_flags(
struct xfs_inode *ip,
enum xfs_prealloc_flags flags)
{
struct xfs_trans *tp;
int error;
error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_writeid,
0, 0, 0, &tp);
if (error)
return error;
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
if (!(flags & XFS_PREALLOC_INVISIBLE)) {
VFS_I(ip)->i_mode &= ~S_ISUID;
if (VFS_I(ip)->i_mode & S_IXGRP)
VFS_I(ip)->i_mode &= ~S_ISGID;
xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
}
if (flags & XFS_PREALLOC_SET)
ip->i_d.di_flags |= XFS_DIFLAG_PREALLOC;
if (flags & XFS_PREALLOC_CLEAR)
ip->i_d.di_flags &= ~XFS_DIFLAG_PREALLOC;
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
if (flags & XFS_PREALLOC_SYNC)
xfs_trans_set_sync(tp);
return xfs_trans_commit(tp);
}
/*
* Fsync operations on directories are much simpler than on regular files,
* as there is no file data to flush, and thus also no need for explicit
* cache flush operations, and there are no non-transaction metadata updates
* on directories either.
*/
STATIC int
xfs_dir_fsync(
struct file *file,
loff_t start,
loff_t end,
int datasync)
{
struct xfs_inode *ip = XFS_I(file->f_mapping->host);
struct xfs_mount *mp = ip->i_mount;
xfs_lsn_t lsn = 0;
trace_xfs_dir_fsync(ip);
xfs_ilock(ip, XFS_ILOCK_SHARED);
if (xfs_ipincount(ip))
lsn = ip->i_itemp->ili_last_lsn;
xfs_iunlock(ip, XFS_ILOCK_SHARED);
if (!lsn)
return 0;
return xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, NULL);
}
STATIC int
xfs_file_fsync(
struct file *file,
loff_t start,
loff_t end,
int datasync)
{
struct inode *inode = file->f_mapping->host;
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
int error = 0;
int log_flushed = 0;
xfs_lsn_t lsn = 0;
trace_xfs_file_fsync(ip);
error = file_write_and_wait_range(file, start, end);
if (error)
return error;
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
xfs_iflags_clear(ip, XFS_ITRUNCATED);
/*
* If we have an RT and/or log subvolume we need to make sure to flush
* the write cache the device used for file data first. This is to
* ensure newly written file data make it to disk before logging the new
* inode size in case of an extending write.
*/
if (XFS_IS_REALTIME_INODE(ip))
xfs_blkdev_issue_flush(mp->m_rtdev_targp);
else if (mp->m_logdev_targp != mp->m_ddev_targp)
xfs_blkdev_issue_flush(mp->m_ddev_targp);
/*
* All metadata updates are logged, which means that we just have to
* flush the log up to the latest LSN that touched the inode. If we have
* concurrent fsync/fdatasync() calls, we need them to all block on the
* log force before we clear the ili_fsync_fields field. This ensures
* that we don't get a racing sync operation that does not wait for the
* metadata to hit the journal before returning. If we race with
* clearing the ili_fsync_fields, then all that will happen is the log
* force will do nothing as the lsn will already be on disk. We can't
* race with setting ili_fsync_fields because that is done under
* XFS_ILOCK_EXCL, and that can't happen because we hold the lock shared
* until after the ili_fsync_fields is cleared.
*/
xfs_ilock(ip, XFS_ILOCK_SHARED);
if (xfs_ipincount(ip)) {
if (!datasync ||
(ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
lsn = ip->i_itemp->ili_last_lsn;
}
if (lsn) {
error = xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, &log_flushed);
ip->i_itemp->ili_fsync_fields = 0;
}
xfs_iunlock(ip, XFS_ILOCK_SHARED);
/*
* If we only have a single device, and the log force about was
* a no-op we might have to flush the data device cache here.
* This can only happen for fdatasync/O_DSYNC if we were overwriting
* an already allocated file and thus do not have any metadata to
* commit.
*/
if (!log_flushed && !XFS_IS_REALTIME_INODE(ip) &&
mp->m_logdev_targp == mp->m_ddev_targp)
xfs_blkdev_issue_flush(mp->m_ddev_targp);
return error;
}
STATIC ssize_t
xfs_file_dio_aio_read(
struct kiocb *iocb,
struct iov_iter *to)
{
struct xfs_inode *ip = XFS_I(file_inode(iocb->ki_filp));
size_t count = iov_iter_count(to);
ssize_t ret;
trace_xfs_file_direct_read(ip, count, iocb->ki_pos);
if (!count)
return 0; /* skip atime */
file_accessed(iocb->ki_filp);
xfs_ilock(ip, XFS_IOLOCK_SHARED);
ret = iomap_dio_rw(iocb, to, &xfs_iomap_ops, NULL);
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
return ret;
}
static noinline ssize_t
xfs_file_dax_read(
struct kiocb *iocb,
struct iov_iter *to)
{
struct xfs_inode *ip = XFS_I(iocb->ki_filp->f_mapping->host);
size_t count = iov_iter_count(to);
ssize_t ret = 0;
trace_xfs_file_dax_read(ip, count, iocb->ki_pos);
if (!count)
return 0; /* skip atime */
if (iocb->ki_flags & IOCB_NOWAIT) {
if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED))
return -EAGAIN;
} else {
xfs_ilock(ip, XFS_IOLOCK_SHARED);
}
ret = dax_iomap_rw(iocb, to, &xfs_iomap_ops);
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
file_accessed(iocb->ki_filp);
return ret;
}
STATIC ssize_t
xfs_file_buffered_aio_read(
struct kiocb *iocb,
struct iov_iter *to)
{
struct xfs_inode *ip = XFS_I(file_inode(iocb->ki_filp));
ssize_t ret;
trace_xfs_file_buffered_read(ip, iov_iter_count(to), iocb->ki_pos);
if (iocb->ki_flags & IOCB_NOWAIT) {
if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED))
return -EAGAIN;
} else {
xfs_ilock(ip, XFS_IOLOCK_SHARED);
}
ret = generic_file_read_iter(iocb, to);
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
return ret;
}
STATIC ssize_t
xfs_file_read_iter(
struct kiocb *iocb,
struct iov_iter *to)
{
struct inode *inode = file_inode(iocb->ki_filp);
struct xfs_mount *mp = XFS_I(inode)->i_mount;
ssize_t ret = 0;
XFS_STATS_INC(mp, xs_read_calls);
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
if (IS_DAX(inode))
ret = xfs_file_dax_read(iocb, to);
else if (iocb->ki_flags & IOCB_DIRECT)
ret = xfs_file_dio_aio_read(iocb, to);
else
ret = xfs_file_buffered_aio_read(iocb, to);
if (ret > 0)
XFS_STATS_ADD(mp, xs_read_bytes, ret);
return ret;
}
/*
* Common pre-write limit and setup checks.
*
* Called with the iolocked held either shared and exclusive according to
* @iolock, and returns with it held. Might upgrade the iolock to exclusive
* if called for a direct write beyond i_size.
*/
STATIC ssize_t
xfs_file_aio_write_checks(
struct kiocb *iocb,
struct iov_iter *from,
int *iolock)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
struct xfs_inode *ip = XFS_I(inode);
ssize_t error = 0;
size_t count = iov_iter_count(from);
bool drained_dio = false;
loff_t isize;
restart:
error = generic_write_checks(iocb, from);
if (error <= 0)
return error;
error = xfs_break_layouts(inode, iolock, BREAK_WRITE);
if (error)
return error;
/*
* For changing security info in file_remove_privs() we need i_rwsem
* exclusively.
*/
if (*iolock == XFS_IOLOCK_SHARED && !IS_NOSEC(inode)) {
xfs_iunlock(ip, *iolock);
*iolock = XFS_IOLOCK_EXCL;
xfs_ilock(ip, *iolock);
goto restart;
}
/*
* If the offset is beyond the size of the file, we need to zero any
* blocks that fall between the existing EOF and the start of this
* write. If zeroing is needed and we are currently holding the
* iolock shared, we need to update it to exclusive which implies
* having to redo all checks before.
*
* We need to serialise against EOF updates that occur in IO
* completions here. We want to make sure that nobody is changing the
* size while we do this check until we have placed an IO barrier (i.e.
* hold the XFS_IOLOCK_EXCL) that prevents new IO from being dispatched.
* The spinlock effectively forms a memory barrier once we have the
* XFS_IOLOCK_EXCL so we are guaranteed to see the latest EOF value
* and hence be able to correctly determine if we need to run zeroing.
*/
spin_lock(&ip->i_flags_lock);
isize = i_size_read(inode);
if (iocb->ki_pos > isize) {
spin_unlock(&ip->i_flags_lock);
if (!drained_dio) {
if (*iolock == XFS_IOLOCK_SHARED) {
xfs_iunlock(ip, *iolock);
*iolock = XFS_IOLOCK_EXCL;
xfs_ilock(ip, *iolock);
iov_iter_reexpand(from, count);
}
/*
* We now have an IO submission barrier in place, but
* AIO can do EOF updates during IO completion and hence
* we now need to wait for all of them to drain. Non-AIO
* DIO will have drained before we are given the
* XFS_IOLOCK_EXCL, and so for most cases this wait is a
* no-op.
*/
inode_dio_wait(inode);
drained_dio = true;
goto restart;
}
trace_xfs_zero_eof(ip, isize, iocb->ki_pos - isize);
error = iomap_zero_range(inode, isize, iocb->ki_pos - isize,
NULL, &xfs_iomap_ops);
if (error)
return error;
} else
spin_unlock(&ip->i_flags_lock);
/*
* Updating the timestamps will grab the ilock again from
* xfs_fs_dirty_inode, so we have to call it after dropping the
* lock above. Eventually we should look into a way to avoid
* the pointless lock roundtrip.
*/
return file_modified(file);
}
static int
xfs_dio_write_end_io(
struct kiocb *iocb,
ssize_t size,
int error,
unsigned flags)
{
struct inode *inode = file_inode(iocb->ki_filp);
struct xfs_inode *ip = XFS_I(inode);
loff_t offset = iocb->ki_pos;
unsigned int nofs_flag;
trace_xfs_end_io_direct_write(ip, offset, size);
if (XFS_FORCED_SHUTDOWN(ip->i_mount))
return -EIO;
if (error)
return error;
if (!size)
return 0;
/*
* Capture amount written on completion as we can't reliably account
* for it on submission.
*/
XFS_STATS_ADD(ip->i_mount, xs_write_bytes, size);
/*
* We can allocate memory here while doing writeback on behalf of
* memory reclaim. To avoid memory allocation deadlocks set the
* task-wide nofs context for the following operations.
*/
nofs_flag = memalloc_nofs_save();
if (flags & IOMAP_DIO_COW) {
error = xfs_reflink_end_cow(ip, offset, size);
if (error)
goto out;
}
/*
* Unwritten conversion updates the in-core isize after extent
* conversion but before updating the on-disk size. Updating isize any
* earlier allows a racing dio read to find unwritten extents before
* they are converted.
*/
if (flags & IOMAP_DIO_UNWRITTEN) {
error = xfs_iomap_write_unwritten(ip, offset, size, true);
goto out;
}
/*
* We need to update the in-core inode size here so that we don't end up
* with the on-disk inode size being outside the in-core inode size. We
* have no other method of updating EOF for AIO, so always do it here
* if necessary.
*
* We need to lock the test/set EOF update as we can be racing with
* other IO completions here to update the EOF. Failing to serialise
* here can result in EOF moving backwards and Bad Things Happen when
* that occurs.
*/
spin_lock(&ip->i_flags_lock);
if (offset + size > i_size_read(inode)) {
i_size_write(inode, offset + size);
spin_unlock(&ip->i_flags_lock);
error = xfs_setfilesize(ip, offset, size);
} else {
spin_unlock(&ip->i_flags_lock);
}
out:
memalloc_nofs_restore(nofs_flag);
return error;
}
static const struct iomap_dio_ops xfs_dio_write_ops = {
.end_io = xfs_dio_write_end_io,
};
/*
* xfs_file_dio_aio_write - handle direct IO writes
*
* Lock the inode appropriately to prepare for and issue a direct IO write.
* By separating it from the buffered write path we remove all the tricky to
* follow locking changes and looping.
*
* If there are cached pages or we're extending the file, we need IOLOCK_EXCL
* until we're sure the bytes at the new EOF have been zeroed and/or the cached
* pages are flushed out.
*
* In most cases the direct IO writes will be done holding IOLOCK_SHARED
* allowing them to be done in parallel with reads and other direct IO writes.
* However, if the IO is not aligned to filesystem blocks, the direct IO layer
* needs to do sub-block zeroing and that requires serialisation against other
* direct IOs to the same block. In this case we need to serialise the
* submission of the unaligned IOs so that we don't get racing block zeroing in
* the dio layer. To avoid the problem with aio, we also need to wait for
* outstanding IOs to complete so that unwritten extent conversion is completed
* before we try to map the overlapping block. This is currently implemented by
* hitting it with a big hammer (i.e. inode_dio_wait()).
*
* Returns with locks held indicated by @iolock and errors indicated by
* negative return values.
*/
STATIC ssize_t
xfs_file_dio_aio_write(
struct kiocb *iocb,
struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
ssize_t ret = 0;
int unaligned_io = 0;
int iolock;
size_t count = iov_iter_count(from);
struct xfs_buftarg *target = XFS_IS_REALTIME_INODE(ip) ?
mp->m_rtdev_targp : mp->m_ddev_targp;
/* DIO must be aligned to device logical sector size */
if ((iocb->ki_pos | count) & target->bt_logical_sectormask)
return -EINVAL;
/*
* Don't take the exclusive iolock here unless the I/O is unaligned to
* the file system block size. We don't need to consider the EOF
* extension case here because xfs_file_aio_write_checks() will relock
* the inode as necessary for EOF zeroing cases and fill out the new
* inode size as appropriate.
*/
if ((iocb->ki_pos & mp->m_blockmask) ||
((iocb->ki_pos + count) & mp->m_blockmask)) {
unaligned_io = 1;
/*
* We can't properly handle unaligned direct I/O to reflink
* files yet, as we can't unshare a partial block.
*/
if (xfs_is_cow_inode(ip)) {
trace_xfs_reflink_bounce_dio_write(ip, iocb->ki_pos, count);
return -EREMCHG;
}
iolock = XFS_IOLOCK_EXCL;
} else {
iolock = XFS_IOLOCK_SHARED;
}
if (iocb->ki_flags & IOCB_NOWAIT) {
/* unaligned dio always waits, bail */
if (unaligned_io)
return -EAGAIN;
if (!xfs_ilock_nowait(ip, iolock))
return -EAGAIN;
} else {
xfs_ilock(ip, iolock);
}
ret = xfs_file_aio_write_checks(iocb, from, &iolock);
if (ret)
goto out;
count = iov_iter_count(from);
/*
* If we are doing unaligned IO, we can't allow any other overlapping IO
* in-flight at the same time or we risk data corruption. Wait for all
* other IO to drain before we submit. If the IO is aligned, demote the
* iolock if we had to take the exclusive lock in
* xfs_file_aio_write_checks() for other reasons.
*/
if (unaligned_io) {
inode_dio_wait(inode);
} else if (iolock == XFS_IOLOCK_EXCL) {
xfs_ilock_demote(ip, XFS_IOLOCK_EXCL);
iolock = XFS_IOLOCK_SHARED;
}
trace_xfs_file_direct_write(ip, count, iocb->ki_pos);
ret = iomap_dio_rw(iocb, from, &xfs_iomap_ops, &xfs_dio_write_ops);
/*
* If unaligned, this is the only IO in-flight. If it has not yet
* completed, wait on it before we release the iolock to prevent
* subsequent overlapping IO.
*/
if (ret == -EIOCBQUEUED && unaligned_io)
inode_dio_wait(inode);
out:
xfs_iunlock(ip, iolock);
/*
* No fallback to buffered IO on errors for XFS, direct IO will either
* complete fully or fail.
*/
ASSERT(ret < 0 || ret == count);
return ret;
}
static noinline ssize_t
xfs_file_dax_write(
struct kiocb *iocb,
struct iov_iter *from)
{
struct inode *inode = iocb->ki_filp->f_mapping->host;
struct xfs_inode *ip = XFS_I(inode);
int iolock = XFS_IOLOCK_EXCL;
ssize_t ret, error = 0;
size_t count;
loff_t pos;
if (iocb->ki_flags & IOCB_NOWAIT) {
if (!xfs_ilock_nowait(ip, iolock))
return -EAGAIN;
} else {
xfs_ilock(ip, iolock);
}
ret = xfs_file_aio_write_checks(iocb, from, &iolock);
if (ret)
goto out;
pos = iocb->ki_pos;
count = iov_iter_count(from);
trace_xfs_file_dax_write(ip, count, pos);
ret = dax_iomap_rw(iocb, from, &xfs_iomap_ops);
if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
i_size_write(inode, iocb->ki_pos);
error = xfs_setfilesize(ip, pos, ret);
}
out:
xfs_iunlock(ip, iolock);
if (error)
return error;
if (ret > 0) {
XFS_STATS_ADD(ip->i_mount, xs_write_bytes, ret);
/* Handle various SYNC-type writes */
ret = generic_write_sync(iocb, ret);
}
return ret;
}
STATIC ssize_t
xfs_file_buffered_aio_write(
struct kiocb *iocb,
struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
struct xfs_inode *ip = XFS_I(inode);
ssize_t ret;
int enospc = 0;
int iolock;
if (iocb->ki_flags & IOCB_NOWAIT)
return -EOPNOTSUPP;
write_retry:
iolock = XFS_IOLOCK_EXCL;
xfs_ilock(ip, iolock);
ret = xfs_file_aio_write_checks(iocb, from, &iolock);
if (ret)
goto out;
/* We can write back this queue in page reclaim */
current->backing_dev_info = inode_to_bdi(inode);
trace_xfs_file_buffered_write(ip, iov_iter_count(from), iocb->ki_pos);
ret = iomap_file_buffered_write(iocb, from, &xfs_iomap_ops);
if (likely(ret >= 0))
iocb->ki_pos += ret;
/*
* If we hit a space limit, try to free up some lingering preallocated
* space before returning an error. In the case of ENOSPC, first try to
* write back all dirty inodes to free up some of the excess reserved
* metadata space. This reduces the chances that the eofblocks scan
* waits on dirty mappings. Since xfs_flush_inodes() is serialized, this
* also behaves as a filter to prevent too many eofblocks scans from
* running at the same time.
*/
if (ret == -EDQUOT && !enospc) {
xfs_iunlock(ip, iolock);
enospc = xfs_inode_free_quota_eofblocks(ip);
if (enospc)
goto write_retry;
enospc = xfs_inode_free_quota_cowblocks(ip);
if (enospc)
goto write_retry;
iolock = 0;
} else if (ret == -ENOSPC && !enospc) {
struct xfs_eofblocks eofb = {0};
enospc = 1;
xfs_flush_inodes(ip->i_mount);
xfs_iunlock(ip, iolock);
eofb.eof_flags = XFS_EOF_FLAGS_SYNC;
xfs_icache_free_eofblocks(ip->i_mount, &eofb);
xfs_icache_free_cowblocks(ip->i_mount, &eofb);
goto write_retry;
}
current->backing_dev_info = NULL;
out:
if (iolock)
xfs_iunlock(ip, iolock);
if (ret > 0) {
XFS_STATS_ADD(ip->i_mount, xs_write_bytes, ret);
/* Handle various SYNC-type writes */
ret = generic_write_sync(iocb, ret);
}
return ret;
}
STATIC ssize_t
xfs_file_write_iter(
struct kiocb *iocb,
struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
struct xfs_inode *ip = XFS_I(inode);
ssize_t ret;
size_t ocount = iov_iter_count(from);
XFS_STATS_INC(ip->i_mount, xs_write_calls);
if (ocount == 0)
return 0;
if (XFS_FORCED_SHUTDOWN(ip->i_mount))
return -EIO;
if (IS_DAX(inode))
return xfs_file_dax_write(iocb, from);
if (iocb->ki_flags & IOCB_DIRECT) {
/*
* Allow a directio write to fall back to a buffered
* write *only* in the case that we're doing a reflink
* CoW. In all other directio scenarios we do not
* allow an operation to fall back to buffered mode.
*/
ret = xfs_file_dio_aio_write(iocb, from);
if (ret != -EREMCHG)
return ret;
}
return xfs_file_buffered_aio_write(iocb, from);
}
static void
xfs_wait_dax_page(
struct inode *inode)
{
struct xfs_inode *ip = XFS_I(inode);
xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
schedule();
xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
}
static int
xfs_break_dax_layouts(
struct inode *inode,
bool *retry)
{
struct page *page;
ASSERT(xfs_isilocked(XFS_I(inode), XFS_MMAPLOCK_EXCL));
page = dax_layout_busy_page(inode->i_mapping);
if (!page)
return 0;
*retry = true;
return ___wait_var_event(&page->_refcount,
atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
0, 0, xfs_wait_dax_page(inode));
}
int
xfs_break_layouts(
struct inode *inode,
uint *iolock,
enum layout_break_reason reason)
{
bool retry;
int error;
ASSERT(xfs_isilocked(XFS_I(inode), XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL));
do {
retry = false;
switch (reason) {
case BREAK_UNMAP:
error = xfs_break_dax_layouts(inode, &retry);
if (error || retry)
break;
/* fall through */
case BREAK_WRITE:
error = xfs_break_leased_layouts(inode, iolock, &retry);
break;
default:
WARN_ON_ONCE(1);
error = -EINVAL;
}
} while (error == 0 && retry);
return error;
}
#define XFS_FALLOC_FL_SUPPORTED \
(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \
FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE | \
FALLOC_FL_INSERT_RANGE | FALLOC_FL_UNSHARE_RANGE)
STATIC long
xfs_file_fallocate(
struct file *file,
int mode,
loff_t offset,
loff_t len)
{
struct inode *inode = file_inode(file);
struct xfs_inode *ip = XFS_I(inode);
long error;
enum xfs_prealloc_flags flags = 0;
uint iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
loff_t new_size = 0;
bool do_file_insert = false;
if (!S_ISREG(inode->i_mode))
return -EINVAL;
if (mode & ~XFS_FALLOC_FL_SUPPORTED)
return -EOPNOTSUPP;
xfs_ilock(ip, iolock);
error = xfs_break_layouts(inode, &iolock, BREAK_UNMAP);
if (error)
goto out_unlock;
/*
* Must wait for all AIO to complete before we continue as AIO can
* change the file size on completion without holding any locks we
* currently hold. We must do this first because AIO can update both
* the on disk and in memory inode sizes, and the operations that follow
* require the in-memory size to be fully up-to-date.
*/
inode_dio_wait(inode);
/*
* Now AIO and DIO has drained we flush and (if necessary) invalidate
* the cached range over the first operation we are about to run.
*
* We care about zero and collapse here because they both run a hole
* punch over the range first. Because that can zero data, and the range
* of invalidation for the shift operations is much larger, we still do
* the required flush for collapse in xfs_prepare_shift().
*
* Insert has the same range requirements as collapse, and we extend the
* file first which can zero data. Hence insert has the same
* flush/invalidate requirements as collapse and so they are both
* handled at the right time by xfs_prepare_shift().
*/
if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE |
FALLOC_FL_COLLAPSE_RANGE)) {
error = xfs_flush_unmap_range(ip, offset, len);
if (error)
goto out_unlock;
}
if (mode & FALLOC_FL_PUNCH_HOLE) {
error = xfs_free_file_space(ip, offset, len);
if (error)
goto out_unlock;
} else if (mode & FALLOC_FL_COLLAPSE_RANGE) {
unsigned int blksize_mask = i_blocksize(inode) - 1;
if (offset & blksize_mask || len & blksize_mask) {
error = -EINVAL;
goto out_unlock;
}
/*
* There is no need to overlap collapse range with EOF,
* in which case it is effectively a truncate operation
*/
if (offset + len >= i_size_read(inode)) {
error = -EINVAL;
goto out_unlock;
}
new_size = i_size_read(inode) - len;
error = xfs_collapse_file_space(ip, offset, len);
if (error)
goto out_unlock;
} else if (mode & FALLOC_FL_INSERT_RANGE) {
unsigned int blksize_mask = i_blocksize(inode) - 1;
loff_t isize = i_size_read(inode);
if (offset & blksize_mask || len & blksize_mask) {
error = -EINVAL;
goto out_unlock;
}
/*
* New inode size must not exceed ->s_maxbytes, accounting for
* possible signed overflow.
*/
if (inode->i_sb->s_maxbytes - isize < len) {
error = -EFBIG;
goto out_unlock;
}
new_size = isize + len;
/* Offset should be less than i_size */
if (offset >= isize) {
error = -EINVAL;
goto out_unlock;
}
do_file_insert = true;
} else {
flags |= XFS_PREALLOC_SET;
if (!(mode & FALLOC_FL_KEEP_SIZE) &&
offset + len > i_size_read(inode)) {
new_size = offset + len;
error = inode_newsize_ok(inode, new_size);
if (error)
goto out_unlock;
}
if (mode & FALLOC_FL_ZERO_RANGE) {
error = xfs_zero_file_space(ip, offset, len);
} else if (mode & FALLOC_FL_UNSHARE_RANGE) {
error = xfs_reflink_unshare(ip, offset, len);
if (error)
goto out_unlock;
if (!xfs_is_always_cow_inode(ip)) {
error = xfs_alloc_file_space(ip, offset, len,
XFS_BMAPI_PREALLOC);
}
} else {
/*
* If always_cow mode we can't use preallocations and
* thus should not create them.
*/
if (xfs_is_always_cow_inode(ip)) {
error = -EOPNOTSUPP;
goto out_unlock;
}
error = xfs_alloc_file_space(ip, offset, len,
XFS_BMAPI_PREALLOC);
}
if (error)
goto out_unlock;
}
if (file->f_flags & O_DSYNC)
flags |= XFS_PREALLOC_SYNC;
error = xfs_update_prealloc_flags(ip, flags);
if (error)
goto out_unlock;
/* Change file size if needed */
if (new_size) {
struct iattr iattr;
iattr.ia_valid = ATTR_SIZE;
iattr.ia_size = new_size;
error = xfs_vn_setattr_size(file_dentry(file), &iattr);
if (error)
goto out_unlock;
}
/*
* Perform hole insertion now that the file size has been
* updated so that if we crash during the operation we don't
* leave shifted extents past EOF and hence losing access to
* the data that is contained within them.
*/
if (do_file_insert)
error = xfs_insert_file_space(ip, offset, len);
out_unlock:
xfs_iunlock(ip, iolock);
return error;
}
STATIC int
xfs_file_fadvise(
struct file *file,
loff_t start,
loff_t end,
int advice)
{
struct xfs_inode *ip = XFS_I(file_inode(file));
int ret;
int lockflags = 0;
/*
* Operations creating pages in page cache need protection from hole
* punching and similar ops
*/
if (advice == POSIX_FADV_WILLNEED) {
lockflags = XFS_IOLOCK_SHARED;
xfs_ilock(ip, lockflags);
}
ret = generic_fadvise(file, start, end, advice);
if (lockflags)
xfs_iunlock(ip, lockflags);
return ret;
}
STATIC loff_t
xfs_file_remap_range(
struct file *file_in,
loff_t pos_in,
struct file *file_out,
loff_t pos_out,
loff_t len,
unsigned int remap_flags)
{
struct inode *inode_in = file_inode(file_in);
struct xfs_inode *src = XFS_I(inode_in);
struct inode *inode_out = file_inode(file_out);
struct xfs_inode *dest = XFS_I(inode_out);
struct xfs_mount *mp = src->i_mount;
loff_t remapped = 0;
xfs_extlen_t cowextsize;
int ret;
if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
return -EINVAL;
if (!xfs_sb_version_hasreflink(&mp->m_sb))
return -EOPNOTSUPP;
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
/* Prepare and then clone file data. */
ret = xfs_reflink_remap_prep(file_in, pos_in, file_out, pos_out,
&len, remap_flags);
if (ret < 0 || len == 0)
return ret;
trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out);
ret = xfs_reflink_remap_blocks(src, pos_in, dest, pos_out, len,
&remapped);
if (ret)
goto out_unlock;
/*
* Carry the cowextsize hint from src to dest if we're sharing the
* entire source file to the entire destination file, the source file
* has a cowextsize hint, and the destination file does not.
*/
cowextsize = 0;
if (pos_in == 0 && len == i_size_read(inode_in) &&
(src->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE) &&
pos_out == 0 && len >= i_size_read(inode_out) &&
!(dest->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE))
cowextsize = src->i_d.di_cowextsize;
ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize,
remap_flags);
out_unlock:
xfs_reflink_remap_unlock(file_in, file_out);
if (ret)
trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
return remapped > 0 ? remapped : ret;
}
STATIC int
xfs_file_open(
struct inode *inode,
struct file *file)
{
if (!(file->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
return -EFBIG;
if (XFS_FORCED_SHUTDOWN(XFS_M(inode->i_sb)))
return -EIO;
file->f_mode |= FMODE_NOWAIT;
return 0;
}
STATIC int
xfs_dir_open(
struct inode *inode,
struct file *file)
{
struct xfs_inode *ip = XFS_I(inode);
int mode;
int error;
error = xfs_file_open(inode, file);
if (error)
return error;
/*
* If there are any blocks, read-ahead block 0 as we're almost
* certain to have the next operation be a read there.
*/
mode = xfs_ilock_data_map_shared(ip);
if (ip->i_d.di_nextents > 0)
error = xfs_dir3_data_readahead(ip, 0, -1);
xfs_iunlock(ip, mode);
return error;
}
STATIC int
xfs_file_release(
struct inode *inode,
struct file *filp)
{
return xfs_release(XFS_I(inode));
}
STATIC int
xfs_file_readdir(
struct file *file,
struct dir_context *ctx)
{
struct inode *inode = file_inode(file);
xfs_inode_t *ip = XFS_I(inode);
size_t bufsize;
/*
* The Linux API doesn't pass down the total size of the buffer
* we read into down to the filesystem. With the filldir concept
* it's not needed for correct information, but the XFS dir2 leaf
* code wants an estimate of the buffer size to calculate it's
* readahead window and size the buffers used for mapping to
* physical blocks.
*
* Try to give it an estimate that's good enough, maybe at some
* point we can change the ->readdir prototype to include the
* buffer size. For now we use the current glibc buffer size.
*/
bufsize = (size_t)min_t(loff_t, XFS_READDIR_BUFSIZE, ip->i_d.di_size);
return xfs_readdir(NULL, ip, ctx, bufsize);
}
STATIC loff_t
xfs_file_llseek(
struct file *file,
loff_t offset,
int whence)
{
struct inode *inode = file->f_mapping->host;
if (XFS_FORCED_SHUTDOWN(XFS_I(inode)->i_mount))
return -EIO;
switch (whence) {
default:
return generic_file_llseek(file, offset, whence);
case SEEK_HOLE:
offset = iomap_seek_hole(inode, offset, &xfs_seek_iomap_ops);
break;
case SEEK_DATA:
offset = iomap_seek_data(inode, offset, &xfs_seek_iomap_ops);
break;
}
if (offset < 0)
return offset;
return vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
}
/*
* Locking for serialisation of IO during page faults. This results in a lock
* ordering of:
*
* mmap_sem (MM)
* sb_start_pagefault(vfs, freeze)
* i_mmaplock (XFS - truncate serialisation)
* page_lock (MM)
* i_lock (XFS - extent map serialisation)
*/
static vm_fault_t
__xfs_filemap_fault(
struct vm_fault *vmf,
enum page_entry_size pe_size,
bool write_fault)
{
struct inode *inode = file_inode(vmf->vma->vm_file);
struct xfs_inode *ip = XFS_I(inode);
vm_fault_t ret;
trace_xfs_filemap_fault(ip, pe_size, write_fault);
if (write_fault) {
sb_start_pagefault(inode->i_sb);
file_update_time(vmf->vma->vm_file);
}
xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
if (IS_DAX(inode)) {
pfn_t pfn;
ret = dax_iomap_fault(vmf, pe_size, &pfn, NULL, &xfs_iomap_ops);
if (ret & VM_FAULT_NEEDDSYNC)
ret = dax_finish_sync_fault(vmf, pe_size, pfn);
} else {
if (write_fault)
ret = iomap_page_mkwrite(vmf, &xfs_iomap_ops);
else
ret = filemap_fault(vmf);
}
xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
if (write_fault)
sb_end_pagefault(inode->i_sb);
return ret;
}
static inline bool
xfs_is_write_fault(
struct vm_fault *vmf)
{
return (vmf->flags & FAULT_FLAG_WRITE) &&
(vmf->vma->vm_flags & VM_SHARED);
}
static vm_fault_t
xfs_filemap_fault(
struct vm_fault *vmf)
{
/* DAX can shortcut the normal fault path on write faults! */
return __xfs_filemap_fault(vmf, PE_SIZE_PTE,
IS_DAX(file_inode(vmf->vma->vm_file)) &&
xfs_is_write_fault(vmf));
}
static vm_fault_t
xfs_filemap_huge_fault(
struct vm_fault *vmf,
enum page_entry_size pe_size)
{
if (!IS_DAX(file_inode(vmf->vma->vm_file)))
return VM_FAULT_FALLBACK;
/* DAX can shortcut the normal fault path on write faults! */
return __xfs_filemap_fault(vmf, pe_size,
xfs_is_write_fault(vmf));
}
static vm_fault_t
xfs_filemap_page_mkwrite(
struct vm_fault *vmf)
{
return __xfs_filemap_fault(vmf, PE_SIZE_PTE, true);
}
/*
* pfn_mkwrite was originally intended to ensure we capture time stamp updates
* on write faults. In reality, it needs to serialise against truncate and
* prepare memory for writing so handle is as standard write fault.
*/
static vm_fault_t
xfs_filemap_pfn_mkwrite(
struct vm_fault *vmf)
{
return __xfs_filemap_fault(vmf, PE_SIZE_PTE, true);
}
static const struct vm_operations_struct xfs_file_vm_ops = {
.fault = xfs_filemap_fault,
.huge_fault = xfs_filemap_huge_fault,
.map_pages = filemap_map_pages,
.page_mkwrite = xfs_filemap_page_mkwrite,
.pfn_mkwrite = xfs_filemap_pfn_mkwrite,
};
STATIC int
xfs_file_mmap(
struct file *filp,
struct vm_area_struct *vma)
{
struct dax_device *dax_dev;
dax_dev = xfs_find_daxdev_for_inode(file_inode(filp));
/*
* We don't support synchronous mappings for non-DAX files and
* for DAX files if underneath dax_device is not synchronous.
*/
if (!daxdev_mapping_supported(vma, dax_dev))
return -EOPNOTSUPP;
file_accessed(filp);
vma->vm_ops = &xfs_file_vm_ops;
if (IS_DAX(file_inode(filp)))
vma->vm_flags |= VM_HUGEPAGE;
return 0;
}
const struct file_operations xfs_file_operations = {
.llseek = xfs_file_llseek,
.read_iter = xfs_file_read_iter,
.write_iter = xfs_file_write_iter,
.splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.iopoll = iomap_dio_iopoll,
.unlocked_ioctl = xfs_file_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = xfs_file_compat_ioctl,
#endif
.mmap = xfs_file_mmap,
.mmap_supported_flags = MAP_SYNC,
.open = xfs_file_open,
.release = xfs_file_release,
.fsync = xfs_file_fsync,
.get_unmapped_area = thp_get_unmapped_area,
.fallocate = xfs_file_fallocate,
.fadvise = xfs_file_fadvise,
.remap_file_range = xfs_file_remap_range,
};
const struct file_operations xfs_dir_file_operations = {
.open = xfs_dir_open,
.read = generic_read_dir,
.iterate_shared = xfs_file_readdir,
.llseek = generic_file_llseek,
.unlocked_ioctl = xfs_file_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = xfs_file_compat_ioctl,
#endif
.fsync = xfs_dir_fsync,
};