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btrfs: make prepare_pages nowait compatible

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Add nowait parameter to the prepare_pages function. In case nowait is
specified for an async buffered write request, do a nowait allocation or
return -EAGAIN.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Stefan Roesch 2022-09-12 12:27:47 -07:00 committed by David Sterba
parent 80f9d24130
commit fc22600012
1 changed files with 35 additions and 8 deletions
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43
fs/btrfs/file.c
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@ -1339,26 +1339,54 @@ static int prepare_uptodate_page(struct inode *inode,
return 0;
}
static unsigned int get_prepare_fgp_flags(bool nowait)
{
unsigned int fgp_flags = FGP_LOCK | FGP_ACCESSED | FGP_CREAT;
if (nowait)
fgp_flags |= FGP_NOWAIT;
return fgp_flags;
}
static gfp_t get_prepare_gfp_flags(struct inode *inode, bool nowait)
{
gfp_t gfp;
gfp = btrfs_alloc_write_mask(inode->i_mapping);
if (nowait) {
gfp &= ~__GFP_DIRECT_RECLAIM;
gfp |= GFP_NOWAIT;
}
return gfp;
}
/*
* this just gets pages into the page cache and locks them down.
*/
static noinline int prepare_pages(struct inode *inode, struct page **pages,
size_t num_pages, loff_t pos,
size_t write_bytes, bool force_uptodate)
size_t write_bytes, bool force_uptodate,
bool nowait)
{
int i;
unsigned long index = pos >> PAGE_SHIFT;
gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
gfp_t mask = get_prepare_gfp_flags(inode, nowait);
unsigned int fgp_flags = get_prepare_fgp_flags(nowait);
int err = 0;
int faili;
for (i = 0; i < num_pages; i++) {
again:
pages[i] = find_or_create_page(inode->i_mapping, index + i,
mask | __GFP_WRITE);
pages[i] = pagecache_get_page(inode->i_mapping, index + i,
fgp_flags, mask | __GFP_WRITE);
if (!pages[i]) {
faili = i - 1;
err = -ENOMEM;
if (nowait)
err = -EAGAIN;
else
err = -ENOMEM;
goto fail;
}
@ -1376,7 +1404,7 @@ again:
pos + write_bytes, false);
if (err) {
put_page(pages[i]);
if (err == -EAGAIN) {
if (!nowait && err == -EAGAIN) {
err = 0;
goto again;
}
@ -1714,8 +1742,7 @@ again:
* contents of pages from loop to loop
*/
ret = prepare_pages(inode, pages, num_pages,
pos, write_bytes,
force_page_uptodate);
pos, write_bytes, force_page_uptodate, false);
if (ret) {
btrfs_delalloc_release_extents(BTRFS_I(inode),
reserve_bytes);