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Diffstat (limited to 'fs/xfs/xfs_aops.c')
-rw-r--r--fs/xfs/xfs_aops.c207
1 files changed, 150 insertions, 57 deletions
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index db2cfb067d0b..faaf716e2080 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -632,38 +632,46 @@ xfs_map_at_offset(
}
/*
- * Test if a given page is suitable for writing as part of an unwritten
- * or delayed allocate extent.
+ * Test if a given page contains at least one buffer of a given @type.
+ * If @check_all_buffers is true, then we walk all the buffers in the page to
+ * try to find one of the type passed in. If it is not set, then the caller only
+ * needs to check the first buffer on the page for a match.
*/
-STATIC int
+STATIC bool
xfs_check_page_type(
struct page *page,
- unsigned int type)
+ unsigned int type,
+ bool check_all_buffers)
{
- if (PageWriteback(page))
- return 0;
+ struct buffer_head *bh;
+ struct buffer_head *head;
- if (page->mapping && page_has_buffers(page)) {
- struct buffer_head *bh, *head;
- int acceptable = 0;
+ if (PageWriteback(page))
+ return false;
+ if (!page->mapping)
+ return false;
+ if (!page_has_buffers(page))
+ return false;
- bh = head = page_buffers(page);
- do {
- if (buffer_unwritten(bh))
- acceptable += (type == XFS_IO_UNWRITTEN);
- else if (buffer_delay(bh))
- acceptable += (type == XFS_IO_DELALLOC);
- else if (buffer_dirty(bh) && buffer_mapped(bh))
- acceptable += (type == XFS_IO_OVERWRITE);
- else
- break;
- } while ((bh = bh->b_this_page) != head);
+ bh = head = page_buffers(page);
+ do {
+ if (buffer_unwritten(bh)) {
+ if (type == XFS_IO_UNWRITTEN)
+ return true;
+ } else if (buffer_delay(bh)) {
+ if (type == XFS_IO_DELALLOC)
+ return true;
+ } else if (buffer_dirty(bh) && buffer_mapped(bh)) {
+ if (type == XFS_IO_OVERWRITE)
+ return true;
+ }
- if (acceptable)
- return 1;
- }
+ /* If we are only checking the first buffer, we are done now. */
+ if (!check_all_buffers)
+ break;
+ } while ((bh = bh->b_this_page) != head);
- return 0;
+ return false;
}
/*
@@ -697,7 +705,7 @@ xfs_convert_page(
goto fail_unlock_page;
if (page->mapping != inode->i_mapping)
goto fail_unlock_page;
- if (!xfs_check_page_type(page, (*ioendp)->io_type))
+ if (!xfs_check_page_type(page, (*ioendp)->io_type, false))
goto fail_unlock_page;
/*
@@ -742,6 +750,15 @@ xfs_convert_page(
p_offset = p_offset ? roundup(p_offset, len) : PAGE_CACHE_SIZE;
page_dirty = p_offset / len;
+ /*
+ * The moment we find a buffer that doesn't match our current type
+ * specification or can't be written, abort the loop and start
+ * writeback. As per the above xfs_imap_valid() check, only
+ * xfs_vm_writepage() can handle partial page writeback fully - we are
+ * limited here to the buffers that are contiguous with the current
+ * ioend, and hence a buffer we can't write breaks that contiguity and
+ * we have to defer the rest of the IO to xfs_vm_writepage().
+ */
bh = head = page_buffers(page);
do {
if (offset >= end_offset)
@@ -750,7 +767,7 @@ xfs_convert_page(
uptodate = 0;
if (!(PageUptodate(page) || buffer_uptodate(bh))) {
done = 1;
- continue;
+ break;
}
if (buffer_unwritten(bh) || buffer_delay(bh) ||
@@ -762,10 +779,11 @@ xfs_convert_page(
else
type = XFS_IO_OVERWRITE;
- if (!xfs_imap_valid(inode, imap, offset)) {
- done = 1;
- continue;
- }
+ /*
+ * imap should always be valid because of the above
+ * partial page end_offset check on the imap.
+ */
+ ASSERT(xfs_imap_valid(inode, imap, offset));
lock_buffer(bh);
if (type != XFS_IO_OVERWRITE)
@@ -777,6 +795,7 @@ xfs_convert_page(
count++;
} else {
done = 1;
+ break;
}
} while (offset += len, (bh = bh->b_this_page) != head);
@@ -868,7 +887,7 @@ xfs_aops_discard_page(
struct buffer_head *bh, *head;
loff_t offset = page_offset(page);
- if (!xfs_check_page_type(page, XFS_IO_DELALLOC))
+ if (!xfs_check_page_type(page, XFS_IO_DELALLOC, true))
goto out_invalidate;
if (XFS_FORCED_SHUTDOWN(ip->i_mount))
@@ -956,14 +975,39 @@ xfs_vm_writepage(
* Given that we do not allow direct reclaim to call us, we should
* never be called while in a filesystem transaction.
*/
- if (WARN_ON(current->flags & PF_FSTRANS))
+ if (WARN_ON_ONCE(current->flags & PF_FSTRANS))
goto redirty;
/* Is this page beyond the end of the file? */
offset = i_size_read(inode);
end_index = offset >> PAGE_CACHE_SHIFT;
last_index = (offset - 1) >> PAGE_CACHE_SHIFT;
- if (page->index >= end_index) {
+
+ /*
+ * The page index is less than the end_index, adjust the end_offset
+ * to the highest offset that this page should represent.
+ * -----------------------------------------------------
+ * | file mapping | <EOF> |
+ * -----------------------------------------------------
+ * | Page ... | Page N-2 | Page N-1 | Page N | |
+ * ^--------------------------------^----------|--------
+ * | desired writeback range | see else |
+ * ---------------------------------^------------------|
+ */
+ if (page->index < end_index)
+ end_offset = (xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT;
+ else {
+ /*
+ * Check whether the page to write out is beyond or straddles
+ * i_size or not.
+ * -------------------------------------------------------
+ * | file mapping | <EOF> |
+ * -------------------------------------------------------
+ * | Page ... | Page N-2 | Page N-1 | Page N | Beyond |
+ * ^--------------------------------^-----------|---------
+ * | | Straddles |
+ * ---------------------------------^-----------|--------|
+ */
unsigned offset_into_page = offset & (PAGE_CACHE_SIZE - 1);
/*
@@ -971,24 +1015,36 @@ xfs_vm_writepage(
* truncate operation that is in progress. We must redirty the
* page so that reclaim stops reclaiming it. Otherwise
* xfs_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
+ * offset is just equal to the EOF.
*/
- if (page->index >= end_index + 1 || offset_into_page == 0)
+ if (page->index > end_index ||
+ (page->index == end_index && offset_into_page == 0))
goto redirty;
/*
* The page straddles i_size. It must be zeroed out on each
* and every writepage invocation because it may be mmapped.
* "A file is mapped in multiples of the page size. For a file
- * that is not a multiple of the page size, the remaining
+ * that is not a multiple of the page size, the remaining
* memory is zeroed when mapped, and writes to that region are
* not written out to the file."
*/
zero_user_segment(page, offset_into_page, PAGE_CACHE_SIZE);
+
+ /* Adjust the end_offset to the end of file */
+ end_offset = offset;
}
- end_offset = min_t(unsigned long long,
- (xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT,
- offset);
len = 1 << inode->i_blkbits;
bh = head = page_buffers(page);
@@ -1169,9 +1225,9 @@ xfs_vm_releasepage(
xfs_count_page_state(page, &delalloc, &unwritten);
- if (WARN_ON(delalloc))
+ if (WARN_ON_ONCE(delalloc))
return 0;
- if (WARN_ON(unwritten))
+ if (WARN_ON_ONCE(unwritten))
return 0;
return try_to_free_buffers(page);
@@ -1325,6 +1381,14 @@ __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;
@@ -1335,6 +1399,12 @@ __xfs_get_blocks(
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;
@@ -1416,9 +1486,8 @@ STATIC ssize_t
xfs_vm_direct_IO(
int rw,
struct kiocb *iocb,
- const struct iovec *iov,
- loff_t offset,
- unsigned long nr_segs)
+ struct iov_iter *iter,
+ loff_t offset)
{
struct inode *inode = iocb->ki_filp->f_mapping->host;
struct block_device *bdev = xfs_find_bdev_for_inode(inode);
@@ -1426,7 +1495,7 @@ xfs_vm_direct_IO(
ssize_t ret;
if (rw & WRITE) {
- size_t size = iov_length(iov, nr_segs);
+ size_t size = iov_iter_count(iter);
/*
* We cannot preallocate a size update transaction here as we
@@ -1438,16 +1507,15 @@ xfs_vm_direct_IO(
if (offset + size > XFS_I(inode)->i_d.di_size)
ioend->io_isdirect = 1;
- ret = __blockdev_direct_IO(rw, iocb, inode, bdev, iov,
- offset, nr_segs,
- xfs_get_blocks_direct,
- xfs_end_io_direct_write, NULL, 0);
+ ret = __blockdev_direct_IO(rw, iocb, inode, bdev, iter,
+ offset, xfs_get_blocks_direct,
+ xfs_end_io_direct_write, NULL,
+ DIO_ASYNC_EXTEND);
if (ret != -EIOCBQUEUED && iocb->private)
goto out_destroy_ioend;
} else {
- ret = __blockdev_direct_IO(rw, iocb, inode, bdev, iov,
- offset, nr_segs,
- xfs_get_blocks_direct,
+ ret = __blockdev_direct_IO(rw, iocb, inode, bdev, iter,
+ offset, xfs_get_blocks_direct,
NULL, NULL, 0);
}
@@ -1546,6 +1614,16 @@ xfs_vm_write_failed(
xfs_vm_kill_delalloc_range(inode, block_offset,
block_offset + bh->b_size);
+
+ /*
+ * This buffer does not contain data anymore. make sure anyone
+ * who finds it knows that for certain.
+ */
+ clear_buffer_delay(bh);
+ clear_buffer_uptodate(bh);
+ clear_buffer_mapped(bh);
+ clear_buffer_new(bh);
+ clear_buffer_dirty(bh);
}
}
@@ -1579,12 +1657,21 @@ xfs_vm_write_begin(
status = __block_write_begin(page, pos, len, xfs_get_blocks);
if (unlikely(status)) {
struct inode *inode = mapping->host;
+ size_t isize = i_size_read(inode);
xfs_vm_write_failed(inode, page, pos, len);
unlock_page(page);
- if (pos + len > i_size_read(inode))
- truncate_pagecache(inode, i_size_read(inode));
+ /*
+ * If the write is beyond EOF, we only want to kill blocks
+ * allocated in this write, not blocks that were previously
+ * written successfully.
+ */
+ if (pos + len > isize) {
+ ssize_t start = max_t(ssize_t, pos, isize);
+
+ truncate_pagecache_range(inode, start, pos + len);
+ }
page_cache_release(page);
page = NULL;
@@ -1595,9 +1682,12 @@ xfs_vm_write_begin(
}
/*
- * On failure, we only need to kill delalloc blocks beyond EOF because they
- * will never be written. For blocks within EOF, generic_write_end() zeros them
- * so they are safe to leave alone and be written with all the other valid data.
+ * On failure, we only need to kill delalloc blocks beyond EOF in the range of
+ * this specific write because they will never be written. Previous writes
+ * beyond EOF where block allocation succeeded do not need to be trashed, so
+ * only new blocks from this write should be trashed. For blocks within
+ * EOF, generic_write_end() zeros them so they are safe to leave alone and be
+ * written with all the other valid data.
*/
STATIC int
xfs_vm_write_end(
@@ -1620,8 +1710,11 @@ xfs_vm_write_end(
loff_t to = pos + len;
if (to > isize) {
- truncate_pagecache(inode, isize);
+ /* only kill blocks in this write beyond EOF */
+ if (pos > isize)
+ isize = pos;
xfs_vm_kill_delalloc_range(inode, isize, to);
+ truncate_pagecache_range(inode, isize, to);
}
}
return ret;
generated by cgit v1.2.3 (git 2.39.0) at 2024-09-10 00:07:29 +0300