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gfs2: iomap direct I/O support

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The page unmapping previously done in gfs2_direct_IO is now done
generically in iomap_dio_rw.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Bob Peterson <rpeterso@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2018-06-19 15:08:02 +01:00
parent bcfe94139a
commit 967bcc91b0
3 changed files with 136 additions and 110 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

100
fs/gfs2/aops.c
View file

@ -84,12 +84,6 @@ static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
return 0;
}
static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
struct buffer_head *bh_result, int create)
{
return gfs2_block_map(inode, lblock, bh_result, 0);
}
/**
* gfs2_writepage_common - Common bits of writepage
* @page: The page to be written
@ -1024,96 +1018,6 @@ static void gfs2_invalidatepage(struct page *page, unsigned int offset,
try_to_release_page(page, 0);
}
/**
* gfs2_ok_for_dio - check that dio is valid on this file
* @ip: The inode
* @offset: The offset at which we are reading or writing
*
* Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
* 1 (to accept the i/o request)
*/
static int gfs2_ok_for_dio(struct gfs2_inode *ip, loff_t offset)
{
/*
* Should we return an error here? I can't see that O_DIRECT for
* a stuffed file makes any sense. For now we'll silently fall
* back to buffered I/O
*/
if (gfs2_is_stuffed(ip))
return 0;
if (offset >= i_size_read(&ip->i_inode))
return 0;
return 1;
}
static ssize_t gfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
struct address_space *mapping = inode->i_mapping;
struct gfs2_inode *ip = GFS2_I(inode);
loff_t offset = iocb->ki_pos;
struct gfs2_holder gh;
int rv;
/*
* Deferred lock, even if its a write, since we do no allocation
* on this path. All we need change is atime, and this lock mode
* ensures that other nodes have flushed their buffered read caches
* (i.e. their page cache entries for this inode). We do not,
* unfortunately have the option of only flushing a range like
* the VFS does.
*/
gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
rv = gfs2_glock_nq(&gh);
if (rv)
goto out_uninit;
rv = gfs2_ok_for_dio(ip, offset);
if (rv != 1)
goto out; /* dio not valid, fall back to buffered i/o */
/*
* Now since we are holding a deferred (CW) lock at this point, you
* might be wondering why this is ever needed. There is a case however
* where we've granted a deferred local lock against a cached exclusive
* glock. That is ok provided all granted local locks are deferred, but
* it also means that it is possible to encounter pages which are
* cached and possibly also mapped. So here we check for that and sort
* them out ahead of the dio. The glock state machine will take care of
* everything else.
*
* If in fact the cached glock state (gl->gl_state) is deferred (CW) in
* the first place, mapping->nr_pages will always be zero.
*/
if (mapping->nrpages) {
loff_t lstart = offset & ~(PAGE_SIZE - 1);
loff_t len = iov_iter_count(iter);
loff_t end = PAGE_ALIGN(offset + len) - 1;
rv = 0;
if (len == 0)
goto out;
if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
unmap_shared_mapping_range(ip->i_inode.i_mapping, offset, len);
rv = filemap_write_and_wait_range(mapping, lstart, end);
if (rv)
goto out;
if (iov_iter_rw(iter) == WRITE)
truncate_inode_pages_range(mapping, lstart, end);
}
rv = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
gfs2_get_block_direct, NULL, NULL, 0);
out:
gfs2_glock_dq(&gh);
out_uninit:
gfs2_holder_uninit(&gh);
return rv;
}
/**
* gfs2_releasepage - free the metadata associated with a page
* @page: the page that's being released
@ -1194,7 +1098,7 @@ static const struct address_space_operations gfs2_writeback_aops = {
.bmap = gfs2_bmap,
.invalidatepage = gfs2_invalidatepage,
.releasepage = gfs2_releasepage,
.direct_IO = gfs2_direct_IO,
.direct_IO = noop_direct_IO,
.migratepage = buffer_migrate_page,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
@ -1211,7 +1115,7 @@ static const struct address_space_operations gfs2_ordered_aops = {
.bmap = gfs2_bmap,
.invalidatepage = gfs2_invalidatepage,
.releasepage = gfs2_releasepage,
.direct_IO = gfs2_direct_IO,
.direct_IO = noop_direct_IO,
.migratepage = buffer_migrate_page,
.is_partially_uptodate = block_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,

14
fs/gfs2/bmap.c
View file

@ -915,6 +915,9 @@ static int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
} else if (flags & IOMAP_WRITE) {
u64 alloc_size;
if (flags & IOMAP_DIRECT)
goto out; /* (see gfs2_file_direct_write) */
len = gfs2_alloc_size(inode, mp, len);
alloc_size = len << inode->i_blkbits;
if (alloc_size < iomap->length)
@ -1082,11 +1085,18 @@ static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
int ret;
trace_gfs2_iomap_start(ip, pos, length, flags);
if (flags & IOMAP_WRITE) {
if ((flags & IOMAP_WRITE) && !(flags & IOMAP_DIRECT)) {
ret = gfs2_iomap_begin_write(inode, pos, length, flags, iomap);
} else {
ret = gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);
release_metapath(&mp);
/*
* Silently fall back to buffered I/O for stuffed files or if
* we've hot a hole (see gfs2_file_direct_write).
*/
if ((flags & IOMAP_WRITE) && (flags & IOMAP_DIRECT) &&
iomap->type != IOMAP_MAPPED)
ret = -ENOTBLK;
}
trace_gfs2_iomap_end(ip, iomap, ret);
return ret;
@ -1100,7 +1110,7 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
struct gfs2_trans *tr = current->journal_info;
struct buffer_head *dibh = iomap->private;
if (!(flags & IOMAP_WRITE))
if ((flags & (IOMAP_WRITE | IOMAP_DIRECT)) != IOMAP_WRITE)
goto out;
if (iomap->type != IOMAP_INLINE) {

130
fs/gfs2/file.c
View file

@ -690,6 +690,85 @@ static int gfs2_fsync(struct file *file, loff_t start, loff_t end,
return ret ? ret : ret1;
}
static ssize_t gfs2_file_direct_read(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
size_t count = iov_iter_count(to);
struct gfs2_holder gh;
ssize_t ret;
if (!count)
return 0; /* skip atime */
gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
ret = gfs2_glock_nq(&gh);
if (ret)
goto out_uninit;
/* fall back to buffered I/O for stuffed files */
ret = -ENOTBLK;
if (gfs2_is_stuffed(ip))
goto out;
ret = iomap_dio_rw(iocb, to, &gfs2_iomap_ops, NULL);
out:
gfs2_glock_dq(&gh);
out_uninit:
gfs2_holder_uninit(&gh);
return ret;
}
static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
struct gfs2_inode *ip = GFS2_I(inode);
size_t len = iov_iter_count(from);
loff_t offset = iocb->ki_pos;
struct gfs2_holder gh;
ssize_t ret;
/*
* Deferred lock, even if its a write, since we do no allocation on
* this path. All we need to change is the atime, and this lock mode
* ensures that other nodes have flushed their buffered read caches
* (i.e. their page cache entries for this inode). We do not,
* unfortunately, have the option of only flushing a range like the
* VFS does.
*/
gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
ret = gfs2_glock_nq(&gh);
if (ret)
goto out_uninit;
/* Silently fall back to buffered I/O when writing beyond EOF */
if (offset + len > i_size_read(&ip->i_inode))
goto out;
ret = iomap_dio_rw(iocb, from, &gfs2_iomap_ops, NULL);
out:
gfs2_glock_dq(&gh);
out_uninit:
gfs2_holder_uninit(&gh);
return ret;
}
static ssize_t gfs2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
ssize_t ret;
if (iocb->ki_flags & IOCB_DIRECT) {
ret = gfs2_file_direct_read(iocb, to);
if (likely(ret != -ENOTBLK))
return ret;
iocb->ki_flags &= ~IOCB_DIRECT;
}
return generic_file_read_iter(iocb, to);
}
/**
* gfs2_file_write_iter - Perform a write to a file
* @iocb: The io context
@ -707,7 +786,7 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
struct file *file = iocb->ki_filp;
struct inode *inode = file_inode(file);
struct gfs2_inode *ip = GFS2_I(inode);
ssize_t ret;
ssize_t written = 0, ret;
ret = gfs2_rsqa_alloc(ip);
if (ret)
@ -724,9 +803,6 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
gfs2_glock_dq_uninit(&gh);
}
if (iocb->ki_flags & IOCB_DIRECT)
return generic_file_write_iter(iocb, from);
inode_lock(inode);
ret = generic_write_checks(iocb, from);
if (ret <= 0)
@ -743,19 +819,55 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
if (ret)
goto out2;
if (iocb->ki_flags & IOCB_DIRECT) {
struct address_space *mapping = file->f_mapping;
loff_t pos, endbyte;
ssize_t buffered;
written = gfs2_file_direct_write(iocb, from);
if (written < 0 || !iov_iter_count(from))
goto out2;
ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);
if (unlikely(ret < 0))
goto out2;
buffered = ret;
/*
* We need to ensure that the page cache pages are written to
* disk and invalidated to preserve the expected O_DIRECT
* semantics.
*/
pos = iocb->ki_pos;
endbyte = pos + buffered - 1;
ret = filemap_write_and_wait_range(mapping, pos, endbyte);
if (!ret) {
iocb->ki_pos += buffered;
written += buffered;
invalidate_mapping_pages(mapping,
pos >> PAGE_SHIFT,
endbyte >> PAGE_SHIFT);
} else {
/*
* We don't know how much we wrote, so just return
* the number of bytes which were direct-written
*/
}
} else {
ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);
if (likely(ret > 0))
iocb->ki_pos += ret;
}
out2:
current->backing_dev_info = NULL;
out:
inode_unlock(inode);
if (likely(ret > 0)) {
iocb->ki_pos += ret;
/* Handle various SYNC-type writes */
ret = generic_write_sync(iocb, ret);
}
return ret;
return written ? written : ret;
}
static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,
@ -1157,7 +1269,7 @@ static int gfs2_flock(struct file *file, int cmd, struct file_lock *fl)
const struct file_operations gfs2_file_fops = {
.llseek = gfs2_llseek,
.read_iter = generic_file_read_iter,
.read_iter = gfs2_file_read_iter,
.write_iter = gfs2_file_write_iter,
.unlocked_ioctl = gfs2_ioctl,
.mmap = gfs2_mmap,
@ -1187,7 +1299,7 @@ const struct file_operations gfs2_dir_fops = {
const struct file_operations gfs2_file_fops_nolock = {
.llseek = gfs2_llseek,
.read_iter = generic_file_read_iter,
.read_iter = gfs2_file_read_iter,
.write_iter = gfs2_file_write_iter,
.unlocked_ioctl = gfs2_ioctl,
.mmap = gfs2_mmap,