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Merge tag 'iomap-5.15-merge-2' of git://git.kernel.org/pub/scm/fs/xfs…
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Pull 'iomap-5.15-merge-2' to support EROFS iomap tail-packing inline:
 - Simplify the bio_end_page usage in the buffered IO code.
 - Support reading inline data at nonzero offsets for erofs.
 - Fix some typos and bad grammar.
 - Convert kmap_atomic usage in the inline data read path.
 - Add some extra inline data input checking.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
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Gao Xiang committed Aug 9, 2021
2 parents 06252e9 + ae44f9c commit 61dc131
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Showing 3 changed files with 110 additions and 87 deletions.
169 changes: 86 additions & 83 deletions fs/iomap/buffered-io.c
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Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@ static inline struct iomap_page *to_iomap_page(struct page *page)
{
/*
* per-block data is stored in the head page. Callers should
* not be dealing with tail pages (and if they are, they can
* not be dealing with tail pages, and if they are, they can
* call thp_head() first.
*/
VM_BUG_ON_PGFLAGS(PageTail(page), page);
Expand Down Expand Up @@ -98,7 +98,7 @@ iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
unsigned last = (poff + plen - 1) >> block_bits;

/*
* If the block size is smaller than the page size we need to check the
* If the block size is smaller than the page size, we need to check the
* per-block uptodate status and adjust the offset and length if needed
* to avoid reading in already uptodate ranges.
*/
Expand Down Expand Up @@ -126,7 +126,7 @@ iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
}

/*
* If the extent spans the block that contains the i_size we need to
* If the extent spans the block that contains the i_size, we need to
* handle both halves separately so that we properly zero data in the
* page cache for blocks that are entirely outside of i_size.
*/
Expand Down Expand Up @@ -205,25 +205,32 @@ struct iomap_readpage_ctx {
struct readahead_control *rac;
};

static void
iomap_read_inline_data(struct inode *inode, struct page *page,
static int iomap_read_inline_data(struct inode *inode, struct page *page,
struct iomap *iomap)
{
size_t size = i_size_read(inode);
size_t size = i_size_read(inode) - iomap->offset;
size_t poff = offset_in_page(iomap->offset);
void *addr;

if (PageUptodate(page))
return;

BUG_ON(page_has_private(page));
BUG_ON(page->index);
BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data));

addr = kmap_atomic(page);
return PAGE_SIZE - poff;

if (WARN_ON_ONCE(size > PAGE_SIZE - poff))
return -EIO;
if (WARN_ON_ONCE(size > PAGE_SIZE -
offset_in_page(iomap->inline_data)))
return -EIO;
if (WARN_ON_ONCE(size > iomap->length))
return -EIO;
if (poff > 0)
iomap_page_create(inode, page);

addr = kmap_local_page(page) + poff;
memcpy(addr, iomap->inline_data, size);
memset(addr + size, 0, PAGE_SIZE - size);
kunmap_atomic(addr);
SetPageUptodate(page);
memset(addr + size, 0, PAGE_SIZE - poff - size);
kunmap_local(addr);
iomap_set_range_uptodate(page, poff, PAGE_SIZE - poff);
return PAGE_SIZE - poff;
}

static inline bool iomap_block_needs_zeroing(struct inode *inode,
Expand All @@ -241,16 +248,12 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
struct iomap_readpage_ctx *ctx = data;
struct page *page = ctx->cur_page;
struct iomap_page *iop;
bool same_page = false, is_contig = false;
loff_t orig_pos = pos;
unsigned poff, plen;
sector_t sector;

if (iomap->type == IOMAP_INLINE) {
WARN_ON_ONCE(pos);
iomap_read_inline_data(inode, page, iomap);
return PAGE_SIZE;
}
if (iomap->type == IOMAP_INLINE)
return iomap_read_inline_data(inode, page, iomap);

/* zero post-eof blocks as the page may be mapped */
iop = iomap_page_create(inode, page);
Expand All @@ -268,16 +271,10 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
if (iop)
atomic_add(plen, &iop->read_bytes_pending);

/* Try to merge into a previous segment if we can */
sector = iomap_sector(iomap, pos);
if (ctx->bio && bio_end_sector(ctx->bio) == sector) {
if (__bio_try_merge_page(ctx->bio, page, plen, poff,
&same_page))
goto done;
is_contig = true;
}

if (!is_contig || bio_full(ctx->bio, plen)) {
if (!ctx->bio ||
bio_end_sector(ctx->bio) != sector ||
bio_add_page(ctx->bio, page, plen, poff) != plen) {
gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
gfp_t orig_gfp = gfp;
unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
Expand All @@ -301,13 +298,12 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
ctx->bio->bi_iter.bi_sector = sector;
bio_set_dev(ctx->bio, iomap->bdev);
ctx->bio->bi_end_io = iomap_read_end_io;
__bio_add_page(ctx->bio, page, plen, poff);
}

bio_add_page(ctx->bio, page, plen, poff);
done:
/*
* Move the caller beyond our range so that it keeps making progress.
* For that we have to include any leading non-uptodate ranges, but
* For that, we have to include any leading non-uptodate ranges, but
* we can skip trailing ones as they will be handled in the next
* iteration.
*/
Expand Down Expand Up @@ -344,9 +340,9 @@ iomap_readpage(struct page *page, const struct iomap_ops *ops)
}

/*
* Just like mpage_readahead and block_read_full_page we always
* Just like mpage_readahead and block_read_full_page, we always
* return 0 and just mark the page as PageError on errors. This
* should be cleaned up all through the stack eventually.
* should be cleaned up throughout the stack eventually.
*/
return 0;
}
Expand Down Expand Up @@ -467,7 +463,7 @@ iomap_releasepage(struct page *page, gfp_t gfp_mask)
/*
* mm accommodates an old ext3 case where clean pages might not have had
* the dirty bit cleared. Thus, it can send actual dirty pages to
* ->releasepage() via shrink_active_list(), skip those here.
* ->releasepage() via shrink_active_list(); skip those here.
*/
if (PageDirty(page) || PageWriteback(page))
return 0;
Expand All @@ -482,7 +478,7 @@ iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
trace_iomap_invalidatepage(page->mapping->host, offset, len);

/*
* If we are invalidating the entire page, clear the dirty state from it
* If we're invalidating the entire page, clear the dirty state from it
* and release it to avoid unnecessary buildup of the LRU.
*/
if (offset == 0 && len == PAGE_SIZE) {
Expand Down Expand Up @@ -589,6 +585,20 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
return 0;
}

static int iomap_write_begin_inline(struct inode *inode,
struct page *page, struct iomap *srcmap)
{
int ret;

/* needs more work for the tailpacking case; disable for now */
if (WARN_ON_ONCE(srcmap->offset != 0))
return -EIO;
ret = iomap_read_inline_data(inode, page, srcmap);
if (ret < 0)
return ret;
return 0;
}

static int
iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
struct page **pagep, struct iomap *iomap, struct iomap *srcmap)
Expand Down Expand Up @@ -618,7 +628,7 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
}

if (srcmap->type == IOMAP_INLINE)
iomap_read_inline_data(inode, page, srcmap);
status = iomap_write_begin_inline(inode, page, srcmap);
else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
status = __block_write_begin_int(page, pos, len, NULL, srcmap);
else
Expand Down Expand Up @@ -650,13 +660,13 @@ static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
/*
* The blocks that were entirely written will now be uptodate, so we
* don't have to worry about a readpage reading them and overwriting a
* partial write. However if we have encountered a short write and only
* partial write. However, if we've encountered a short write and only
* partially written into a block, it will not be marked uptodate, so a
* readpage might come in and destroy our partial write.
*
* Do the simplest thing, and just treat any short write to a non
* uptodate page as a zero-length write, and force the caller to redo
* the whole thing.
* Do the simplest thing and just treat any short write to a
* non-uptodate page as a zero-length write, and force the caller to
* redo the whole thing.
*/
if (unlikely(copied < len && !PageUptodate(page)))
return 0;
Expand All @@ -671,12 +681,12 @@ static size_t iomap_write_end_inline(struct inode *inode, struct page *page,
void *addr;

WARN_ON_ONCE(!PageUptodate(page));
BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data));
BUG_ON(!iomap_inline_data_valid(iomap));

flush_dcache_page(page);
addr = kmap_atomic(page);
memcpy(iomap->inline_data + pos, addr + pos, copied);
kunmap_atomic(addr);
addr = kmap_local_page(page) + pos;
memcpy(iomap_inline_data(iomap, pos), addr, copied);
kunmap_local(addr);

mark_inode_dirty(inode);
return copied;
Expand Down Expand Up @@ -744,7 +754,7 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
bytes = length;

/*
* Bring in the user page that we will copy from _first_.
* Bring in the user page that we'll copy from _first_.
* Otherwise there's a nasty deadlock on copying from the
* same page as we're writing to, without it being marked
* up-to-date.
Expand Down Expand Up @@ -1153,7 +1163,7 @@ static void iomap_writepage_end_bio(struct bio *bio)
* Submit the final bio for an ioend.
*
* If @error is non-zero, it means that we have a situation where some part of
* the submission process has failed after we have marked paged for writeback
* the submission process has failed after we've marked pages for writeback
* and unlocked them. In this situation, we need to fail the bio instead of
* submitting it. This typically only happens on a filesystem shutdown.
*/
Expand All @@ -1168,7 +1178,7 @@ iomap_submit_ioend(struct iomap_writepage_ctx *wpc, struct iomap_ioend *ioend,
error = wpc->ops->prepare_ioend(ioend, error);
if (error) {
/*
* If we are failing the IO now, just mark the ioend with an
* If we're failing the IO now, just mark the ioend with an
* error and finish it. This will run IO completion immediately
* as there is only one reference to the ioend at this point in
* time.
Expand Down Expand Up @@ -1210,7 +1220,7 @@ iomap_alloc_ioend(struct inode *inode, struct iomap_writepage_ctx *wpc,
/*
* Allocate a new bio, and chain the old bio to the new one.
*
* Note that we have to do perform the chaining in this unintuitive order
* Note that we have to perform the chaining in this unintuitive order
* so that the bi_private linkage is set up in the right direction for the
* traversal in iomap_finish_ioend().
*/
Expand Down Expand Up @@ -1249,7 +1259,7 @@ iomap_can_add_to_ioend(struct iomap_writepage_ctx *wpc, loff_t offset,

/*
* Test to see if we have an existing ioend structure that we could append to
* first, otherwise finish off the current ioend and start another.
* first; otherwise finish off the current ioend and start another.
*/
static void
iomap_add_to_ioend(struct inode *inode, loff_t offset, struct page *page,
Expand All @@ -1259,37 +1269,30 @@ iomap_add_to_ioend(struct inode *inode, loff_t offset, struct page *page,
sector_t sector = iomap_sector(&wpc->iomap, offset);
unsigned len = i_blocksize(inode);
unsigned poff = offset & (PAGE_SIZE - 1);
bool merged, same_page = false;

if (!wpc->ioend || !iomap_can_add_to_ioend(wpc, offset, sector)) {
if (wpc->ioend)
list_add(&wpc->ioend->io_list, iolist);
wpc->ioend = iomap_alloc_ioend(inode, wpc, offset, sector, wbc);
}

merged = __bio_try_merge_page(wpc->ioend->io_bio, page, len, poff,
&same_page);
if (iop)
atomic_add(len, &iop->write_bytes_pending);

if (!merged) {
if (bio_full(wpc->ioend->io_bio, len)) {
wpc->ioend->io_bio =
iomap_chain_bio(wpc->ioend->io_bio);
}
bio_add_page(wpc->ioend->io_bio, page, len, poff);
if (bio_add_page(wpc->ioend->io_bio, page, len, poff) != len) {
wpc->ioend->io_bio = iomap_chain_bio(wpc->ioend->io_bio);
__bio_add_page(wpc->ioend->io_bio, page, len, poff);
}

if (iop)
atomic_add(len, &iop->write_bytes_pending);
wpc->ioend->io_size += len;
wbc_account_cgroup_owner(wbc, page, len);
}

/*
* We implement an immediate ioend submission policy here to avoid needing to
* chain multiple ioends and hence nest mempool allocations which can violate
* forward progress guarantees we need to provide. The current ioend we are
* adding blocks to is cached on the writepage context, and if the new block
* does not append to the cached ioend it will create a new ioend and cache that
* the forward progress guarantees we need to provide. The current ioend we're
* adding blocks to is cached in the writepage context, and if the new block
* doesn't append to the cached ioend, it will create a new ioend and cache that
* instead.
*
* If a new ioend is created and cached, the old ioend is returned and queued
Expand Down Expand Up @@ -1351,7 +1354,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
if (unlikely(error)) {
/*
* Let the filesystem know what portion of the current page
* failed to map. If the page wasn't been added to ioend, it
* failed to map. If the page hasn't been added to ioend, it
* won't be affected by I/O completion and we must unlock it
* now.
*/
Expand All @@ -1368,7 +1371,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
unlock_page(page);

/*
* Preserve the original error if there was one, otherwise catch
* Preserve the original error if there was one; catch
* submission errors here and propagate into subsequent ioend
* submissions.
*/
Expand All @@ -1395,8 +1398,8 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
/*
* Write out a dirty page.
*
* For delalloc space on the page we need to allocate space and flush it.
* For unwritten space on the page we need to start the conversion to
* For delalloc space on the page, we need to allocate space and flush it.
* For unwritten space on the page, we need to start the conversion to
* regular allocated space.
*/
static int
Expand All @@ -1411,7 +1414,7 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
trace_iomap_writepage(inode, page_offset(page), PAGE_SIZE);

/*
* Refuse to write the page out if we are called from reclaim context.
* Refuse to write the page out if we're called from reclaim context.
*
* This avoids stack overflows when called from deeply used stacks in
* random callers for direct reclaim or memcg reclaim. We explicitly
Expand Down Expand Up @@ -1456,20 +1459,20 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
unsigned offset_into_page = offset & (PAGE_SIZE - 1);

/*
* Skip the page if it is fully outside i_size, e.g. due to a
* truncate operation that is in progress. We must redirty the
* Skip the page if it's fully outside i_size, e.g. due to a
* truncate operation that's in progress. We must redirty the
* page so that reclaim stops reclaiming it. Otherwise
* iomap_vm_releasepage() is called on it and gets confused.
*
* Note that the end_index is unsigned long, it would overflow
* if the given offset is greater than 16TB on 32-bit system
* and if we do check the page is fully outside i_size or not
* via "if (page->index >= end_index + 1)" as "end_index + 1"
* will be evaluated to 0. Hence this page will be redirtied
* and be written out repeatedly which would result in an
* infinite loop, the user program that perform this operation
* will hang. Instead, we can verify this situation by checking
* if the page to write is totally beyond the i_size or if it's
* Note that the end_index is unsigned long. If the given
* offset is greater than 16TB on a 32-bit system then if we
* checked if the page is fully outside i_size with
* "if (page->index >= end_index + 1)", "end_index + 1" would
* overflow and evaluate to 0. Hence this page would be
* redirtied and written out repeatedly, which would result in
* an infinite loop; the user program performing this operation
* would hang. Instead, we can detect this situation by
* checking if the page is totally beyond i_size or if its
* offset is just equal to the EOF.
*/
if (page->index > end_index ||
Expand Down
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