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Merge branch 'xfs-dio-extend-fix' into for-next

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Conflicts:
	fs/xfs/xfs_file.c
This commit is contained in:
Dave Chinner 2015-04-16 22:13:18 +10:00
commit 542c311813
3 changed files with 239 additions and 82 deletions
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270
fs/xfs/xfs_aops.c
View File

@ -1233,6 +1233,117 @@ xfs_vm_releasepage(
return try_to_free_buffers(page);
}
/*
* When we map a DIO buffer, we may need to attach an ioend that describes the
* type of write IO we are doing. This passes to the completion function the
* operations it needs to perform. If the mapping is for an overwrite wholly
* within the EOF then we don't need an ioend and so we don't allocate one.
* This avoids the unnecessary overhead of allocating and freeing ioends for
* workloads that don't require transactions on IO completion.
*
* If we get multiple mappings in a single IO, we might be mapping different
* types. But because the direct IO can only have a single private pointer, we
* need to ensure that:
*
* a) i) the ioend spans the entire region of unwritten mappings; or
* ii) the ioend spans all the mappings that cross or are beyond EOF; and
* b) if it contains unwritten extents, it is *permanently* marked as such
*
* We could do this by chaining ioends like buffered IO does, but we only
* actually get one IO completion callback from the direct IO, and that spans
* the entire IO regardless of how many mappings and IOs are needed to complete
* the DIO. There is only going to be one reference to the ioend and its life
* cycle is constrained by the DIO completion code. hence we don't need
* reference counting here.
*/
static void
xfs_map_direct(
struct inode *inode,
struct buffer_head *bh_result,
struct xfs_bmbt_irec *imap,
xfs_off_t offset)
{
struct xfs_ioend *ioend;
xfs_off_t size = bh_result->b_size;
int type;
if (ISUNWRITTEN(imap))
type = XFS_IO_UNWRITTEN;
else
type = XFS_IO_OVERWRITE;
trace_xfs_gbmap_direct(XFS_I(inode), offset, size, type, imap);
if (bh_result->b_private) {
ioend = bh_result->b_private;
ASSERT(ioend->io_size > 0);
ASSERT(offset >= ioend->io_offset);
if (offset + size > ioend->io_offset + ioend->io_size)
ioend->io_size = offset - ioend->io_offset + size;
if (type == XFS_IO_UNWRITTEN && type != ioend->io_type)
ioend->io_type = XFS_IO_UNWRITTEN;
trace_xfs_gbmap_direct_update(XFS_I(inode), ioend->io_offset,
ioend->io_size, ioend->io_type,
imap);
} else if (type == XFS_IO_UNWRITTEN ||
offset + size > i_size_read(inode)) {
ioend = xfs_alloc_ioend(inode, type);
ioend->io_offset = offset;
ioend->io_size = size;
bh_result->b_private = ioend;
set_buffer_defer_completion(bh_result);
trace_xfs_gbmap_direct_new(XFS_I(inode), offset, size, type,
imap);
} else {
trace_xfs_gbmap_direct_none(XFS_I(inode), offset, size, type,
imap);
}
}
/*
* If this is O_DIRECT or the mpage code calling tell them how large the mapping
* is, so that we can avoid repeated get_blocks calls.
*
* If the mapping spans EOF, then we have to break the mapping up as the mapping
* for blocks beyond EOF must be marked new so that sub block regions can be
* correctly zeroed. We can't do this for mappings within EOF unless the mapping
* was just allocated or is unwritten, otherwise the callers would overwrite
* existing data with zeros. Hence we have to split the mapping into a range up
* to and including EOF, and a second mapping for beyond EOF.
*/
static void
xfs_map_trim_size(
struct inode *inode,
sector_t iblock,
struct buffer_head *bh_result,
struct xfs_bmbt_irec *imap,
xfs_off_t offset,
ssize_t size)
{
xfs_off_t mapping_size;
mapping_size = imap->br_startoff + imap->br_blockcount - iblock;
mapping_size <<= inode->i_blkbits;
ASSERT(mapping_size > 0);
if (mapping_size > size)
mapping_size = size;
if (offset < i_size_read(inode) &&
offset + mapping_size >= i_size_read(inode)) {
/* limit mapping to block that spans EOF */
mapping_size = roundup_64(i_size_read(inode) - offset,
1 << inode->i_blkbits);
}
if (mapping_size > LONG_MAX)
mapping_size = LONG_MAX;
bh_result->b_size = mapping_size;
}
STATIC int
__xfs_get_blocks(
struct inode *inode,
@ -1321,31 +1432,37 @@ __xfs_get_blocks(
xfs_iunlock(ip, lockmode);
}
trace_xfs_get_blocks_alloc(ip, offset, size, 0, &imap);
trace_xfs_get_blocks_alloc(ip, offset, size,
ISUNWRITTEN(&imap) ? XFS_IO_UNWRITTEN
: XFS_IO_DELALLOC, &imap);
} else if (nimaps) {
trace_xfs_get_blocks_found(ip, offset, size, 0, &imap);
trace_xfs_get_blocks_found(ip, offset, size,
ISUNWRITTEN(&imap) ? XFS_IO_UNWRITTEN
: XFS_IO_OVERWRITE, &imap);
xfs_iunlock(ip, lockmode);
} else {
trace_xfs_get_blocks_notfound(ip, offset, size);
goto out_unlock;
}
/* trim mapping down to size requested */
if (direct || size > (1 << inode->i_blkbits))
xfs_map_trim_size(inode, iblock, bh_result,
&imap, offset, size);
/*
* For unwritten extents do not report a disk address in the buffered
* read case (treat as if we're reading into a hole).
*/
if (imap.br_startblock != HOLESTARTBLOCK &&
imap.br_startblock != DELAYSTARTBLOCK) {
/*
* For unwritten extents do not report a disk address on
* the read case (treat as if we're reading into a hole).
*/
if (create || !ISUNWRITTEN(&imap))
xfs_map_buffer(inode, bh_result, &imap, offset);
if (create && ISUNWRITTEN(&imap)) {
if (direct) {
bh_result->b_private = inode;
set_buffer_defer_completion(bh_result);
}
imap.br_startblock != DELAYSTARTBLOCK &&
(create || !ISUNWRITTEN(&imap))) {
xfs_map_buffer(inode, bh_result, &imap, offset);
if (ISUNWRITTEN(&imap))
set_buffer_unwritten(bh_result);
}
/* direct IO needs special help */
if (create && direct)
xfs_map_direct(inode, bh_result, &imap, offset);
}
/*
@ -1378,39 +1495,6 @@ __xfs_get_blocks(
}
}
/*
* If this is O_DIRECT or the mpage code calling tell them how large
* the mapping is, so that we can avoid repeated get_blocks calls.
*
* If the mapping spans EOF, then we have to break the mapping up as the
* mapping for blocks beyond EOF must be marked new so that sub block
* regions can be correctly zeroed. We can't do this for mappings within
* EOF unless the mapping was just allocated or is unwritten, otherwise
* the callers would overwrite existing data with zeros. Hence we have
* to split the mapping into a range up to and including EOF, and a
* second mapping for beyond EOF.
*/
if (direct || size > (1 << inode->i_blkbits)) {
xfs_off_t mapping_size;
mapping_size = imap.br_startoff + imap.br_blockcount - iblock;
mapping_size <<= inode->i_blkbits;
ASSERT(mapping_size > 0);
if (mapping_size > size)
mapping_size = size;
if (offset < i_size_read(inode) &&
offset + mapping_size >= i_size_read(inode)) {
/* limit mapping to block that spans EOF */
mapping_size = roundup_64(i_size_read(inode) - offset,
1 << inode->i_blkbits);
}
if (mapping_size > LONG_MAX)
mapping_size = LONG_MAX;
bh_result->b_size = mapping_size;
}
return 0;
out_unlock:
@ -1441,9 +1525,11 @@ xfs_get_blocks_direct(
/*
* Complete a direct I/O write request.
*
* If the private argument is non-NULL __xfs_get_blocks signals us that we
* need to issue a transaction to convert the range from unwritten to written
* extents.
* The ioend structure is passed from __xfs_get_blocks() to tell us what to do.
* If no ioend exists (i.e. @private == NULL) then the write IO is an overwrite
* wholly within the EOF and so there is nothing for us to do. Note that in this
* case the completion can be called in interrupt context, whereas if we have an
* ioend we will always be called in task context (i.e. from a workqueue).
*/
STATIC void
xfs_end_io_direct_write(
@ -1455,43 +1541,71 @@ xfs_end_io_direct_write(
struct inode *inode = file_inode(iocb->ki_filp);
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
struct xfs_ioend *ioend = private;
trace_xfs_gbmap_direct_endio(ip, offset, size,
ioend ? ioend->io_type : 0, NULL);
if (!ioend) {
ASSERT(offset + size <= i_size_read(inode));
return;
}
if (XFS_FORCED_SHUTDOWN(mp))
return;
goto out_end_io;
/*
* While the generic direct I/O code updates the inode size, it does
* so only after the end_io handler is called, which means our
* end_io handler thinks the on-disk size is outside the in-core
* size. To prevent this just update it a little bit earlier here.
* dio completion end_io functions are only called on writes if more
* than 0 bytes was written.
*/
ASSERT(size > 0);
/*
* The ioend only maps whole blocks, while the IO may be sector aligned.
* Hence the ioend offset/size may not match the IO offset/size exactly.
* Because we don't map overwrites within EOF into the ioend, the offset
* may not match, but only if the endio spans EOF. Either way, write
* the IO sizes into the ioend so that completion processing does the
* right thing.
*/
ASSERT(offset + size <= ioend->io_offset + ioend->io_size);
ioend->io_size = size;
ioend->io_offset = offset;
/*
* The ioend tells us whether we are doing unwritten extent conversion
* or an append transaction that updates the on-disk file size. These
* cases are the only cases where we should *potentially* be needing
* to update the VFS inode size.
*
* 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);
/*
* For direct I/O we do not know if we need to allocate blocks or not,
* so we can't preallocate an append transaction, as that results in
* nested reservations and log space deadlocks. Hence allocate the
* transaction here. While this is sub-optimal and can block IO
* completion for some time, we're stuck with doing it this way until
* we can pass the ioend to the direct IO allocation callbacks and
* avoid nesting that way.
* If we are doing an append IO that needs to update the EOF on disk,
* do the transaction reserve now so we can use common end io
* processing. Stashing the error (if there is one) in the ioend will
* result in the ioend processing passing on the error if it is
* possible as we can't return it from here.
*/
if (private && size > 0) {
xfs_iomap_write_unwritten(ip, offset, size);
} else if (offset + size > ip->i_d.di_size) {
struct xfs_trans *tp;
int error;
if (ioend->io_type == XFS_IO_OVERWRITE)
ioend->io_error = xfs_setfilesize_trans_alloc(ioend);
tp = xfs_trans_alloc(mp, XFS_TRANS_FSYNC_TS);
error = xfs_trans_reserve(tp, &M_RES(mp)->tr_fsyncts, 0, 0);
if (error) {
xfs_trans_cancel(tp, 0);
return;
}
xfs_setfilesize(ip, tp, offset, size);
}
out_end_io:
xfs_end_io(&ioend->io_work);
return;
}
STATIC ssize_t

46
fs/xfs/xfs_file.c
View File

@ -569,20 +569,41 @@ xfs_file_aio_write_checks(
* 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);
if (*pos > i_size_read(inode)) {
bool zero = false;
spin_unlock(&ip->i_flags_lock);
if (*iolock == XFS_IOLOCK_SHARED) {
xfs_rw_iunlock(ip, *iolock);
*iolock = XFS_IOLOCK_EXCL;
xfs_rw_ilock(ip, *iolock);
/*
* 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);
goto restart;
}
error = xfs_zero_eof(ip, *pos, i_size_read(inode), &zero);
if (error)
return error;
}
} else
spin_unlock(&ip->i_flags_lock);
/*
* Updating the timestamps will grab the ilock again from
@ -644,6 +665,8 @@ xfs_file_dio_aio_write(
int iolock;
size_t count = iov_iter_count(from);
loff_t pos = iocb->ki_pos;
loff_t end;
struct iov_iter data;
struct xfs_buftarg *target = XFS_IS_REALTIME_INODE(ip) ?
mp->m_rtdev_targp : mp->m_ddev_targp;
@ -683,10 +706,11 @@ xfs_file_dio_aio_write(
if (ret)
goto out;
iov_iter_truncate(from, count);
end = pos + count - 1;
if (mapping->nrpages) {
ret = filemap_write_and_wait_range(VFS_I(ip)->i_mapping,
pos, pos + count - 1);
pos, end);
if (ret)
goto out;
/*
@ -696,7 +720,7 @@ xfs_file_dio_aio_write(
*/
ret = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping,
pos >> PAGE_CACHE_SHIFT,
(pos + count - 1) >> PAGE_CACHE_SHIFT);
end >> PAGE_CACHE_SHIFT);
WARN_ON_ONCE(ret);
ret = 0;
}
@ -713,8 +737,22 @@ xfs_file_dio_aio_write(
}
trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0);
ret = generic_file_direct_write(iocb, from, pos);
data = *from;
ret = mapping->a_ops->direct_IO(WRITE, iocb, &data, pos);
/* see generic_file_direct_write() for why this is necessary */
if (mapping->nrpages) {
invalidate_inode_pages2_range(mapping,
pos >> PAGE_CACHE_SHIFT,
end >> PAGE_CACHE_SHIFT);
}
if (ret > 0) {
pos += ret;
iov_iter_advance(from, ret);
iocb->ki_pos = pos;
}
out:
xfs_rw_iunlock(ip, iolock);

5
fs/xfs/xfs_trace.h
View File

@ -1221,6 +1221,11 @@ DEFINE_IOMAP_EVENT(xfs_map_blocks_found);
DEFINE_IOMAP_EVENT(xfs_map_blocks_alloc);
DEFINE_IOMAP_EVENT(xfs_get_blocks_found);
DEFINE_IOMAP_EVENT(xfs_get_blocks_alloc);
DEFINE_IOMAP_EVENT(xfs_gbmap_direct);
DEFINE_IOMAP_EVENT(xfs_gbmap_direct_new);
DEFINE_IOMAP_EVENT(xfs_gbmap_direct_update);
DEFINE_IOMAP_EVENT(xfs_gbmap_direct_none);
DEFINE_IOMAP_EVENT(xfs_gbmap_direct_endio);
DECLARE_EVENT_CLASS(xfs_simple_io_class,
TP_PROTO(struct xfs_inode *ip, xfs_off_t offset, ssize_t count),