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Btrfs: btrfs_page_mkwrite: Reserve space in sectorsized units

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In subpagesize-blocksize scenario, if i_size occurs in a block which is not
the last block in the page, then the space to be reserved should be calculated
appropriately.

Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Chandan Rajendra 2016-01-21 15:55:57 +05:30 committed by David Sterba
parent 9703fefe0b
commit d0b7da88f6
1 changed files with 30 additions and 5 deletions
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35
fs/btrfs/inode.c
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@ -8802,15 +8802,28 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
loff_t size;
int ret;
int reserved = 0;
u64 reserved_space;
u64 page_start;
u64 page_end;
u64 end;
reserved_space = PAGE_CACHE_SIZE;
sb_start_pagefault(inode->i_sb);
page_start = page_offset(page);
page_end = page_start + PAGE_CACHE_SIZE - 1;
end = page_end;
/*
* Reserving delalloc space after obtaining the page lock can lead to
* deadlock. For example, if a dirty page is locked by this function
* and the call to btrfs_delalloc_reserve_space() ends up triggering
* dirty page write out, then the btrfs_writepage() function could
* end up waiting indefinitely to get a lock on the page currently
* being processed by btrfs_page_mkwrite() function.
*/
ret = btrfs_delalloc_reserve_space(inode, page_start,
PAGE_CACHE_SIZE);
reserved_space);
if (!ret) {
ret = file_update_time(vma->vm_file);
reserved = 1;
@ -8844,7 +8857,7 @@ again:
* we can't set the delalloc bits if there are pending ordered
* extents. Drop our locks and wait for them to finish
*/
ordered = btrfs_lookup_ordered_extent(inode, page_start);
ordered = btrfs_lookup_ordered_range(inode, page_start, page_end);
if (ordered) {
unlock_extent_cached(io_tree, page_start, page_end,
&cached_state, GFP_NOFS);
@ -8854,6 +8867,18 @@ again:
goto again;
}
if (page->index == ((size - 1) >> PAGE_CACHE_SHIFT)) {
reserved_space = round_up(size - page_start, root->sectorsize);
if (reserved_space < PAGE_CACHE_SIZE) {
end = page_start + reserved_space - 1;
spin_lock(&BTRFS_I(inode)->lock);
BTRFS_I(inode)->outstanding_extents++;
spin_unlock(&BTRFS_I(inode)->lock);
btrfs_delalloc_release_space(inode, page_start,
PAGE_CACHE_SIZE - reserved_space);
}
}
/*
* XXX - page_mkwrite gets called every time the page is dirtied, even
* if it was already dirty, so for space accounting reasons we need to
@ -8861,12 +8886,12 @@ again:
* is probably a better way to do this, but for now keep consistent with
* prepare_pages in the normal write path.
*/
clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, page_end,
clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, end,
EXTENT_DIRTY | EXTENT_DELALLOC |
EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
0, 0, &cached_state, GFP_NOFS);
ret = btrfs_set_extent_delalloc(inode, page_start, page_end,
ret = btrfs_set_extent_delalloc(inode, page_start, end,
&cached_state);
if (ret) {
unlock_extent_cached(io_tree, page_start, page_end,
@ -8905,7 +8930,7 @@ out_unlock:
}
unlock_page(page);
out:
btrfs_delalloc_release_space(inode, page_start, PAGE_CACHE_SIZE);
btrfs_delalloc_release_space(inode, page_start, reserved_space);
out_noreserve:
sb_end_pagefault(inode->i_sb);
return ret;