Reorder compress_file_range so that the main compression flow happens
straight line and not in branches. To do this ensure that pages is
always zeroed before a page allocation happens, which allows the
cleanup_and_bail_uncompressed label to clean up the page allocations
as needed.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/btrfs/inode.c | 165 +++++++++++++++++++++++------------------------
1 file changed, 81 insertions(+), 84 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 09f8c6f2f4bf88..e7c05d07ff50f8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -841,10 +841,11 @@ static void compress_file_range(struct btrfs_work *work)
u64 actual_end;
u64 i_size;
int ret = 0;
- struct page **pages = NULL;
+ struct page **pages;
unsigned long nr_pages;
unsigned long total_compressed = 0;
unsigned long total_in = 0;
+ unsigned int poff;
int i;
int will_compress;
int compress_type = fs_info->compress_type;
@@ -867,6 +868,7 @@ static void compress_file_range(struct btrfs_work *work)
actual_end = min_t(u64, i_size, end + 1);
again:
will_compress = 0;
+ pages = NULL;
nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
nr_pages = min_t(unsigned long, nr_pages, BTRFS_MAX_COMPRESSED_PAGES);
@@ -910,66 +912,62 @@ static void compress_file_range(struct btrfs_work *work)
ret = 0;
/*
- * we do compression for mount -o compress and when the
- * inode has not been flagged as nocompress. This flag can
- * change at any time if we discover bad compression ratios.
+ * We do compression for mount -o compress and when the inode has not
+ * been flagged as nocompress. This flag can change at any time if we
+ * discover bad compression ratios.
*/
- if (inode_need_compress(inode, start, end)) {
- WARN_ON(pages);
- pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
- if (!pages) {
- /* just bail out to the uncompressed code */
- nr_pages = 0;
- goto cont;
- }
+ if (!inode_need_compress(inode, start, end))
+ goto cont;
- if (inode->defrag_compress)
- compress_type = inode->defrag_compress;
- else if (inode->prop_compress)
- compress_type = inode->prop_compress;
+ pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
+ if (!pages) {
+ /* just bail out to the uncompressed code */
+ nr_pages = 0;
+ goto cont;
+ }
- /*
- * we need to call clear_page_dirty_for_io on each
- * page in the range. Otherwise applications with the file
- * mmap'd can wander in and change the page contents while
- * we are compressing them.
- *
- * If the compression fails for any reason, we set the pages
- * dirty again later on.
- *
- * Note that the remaining part is redirtied, the start pointer
- * has moved, the end is the original one.
- */
- if (!redirty) {
- extent_range_clear_dirty_for_io(&inode->vfs_inode, start, end);
- redirty = 1;
- }
+ if (inode->defrag_compress)
+ compress_type = inode->defrag_compress;
+ else if (inode->prop_compress)
+ compress_type = inode->prop_compress;
+
+ /*
+ * We need to call clear_page_dirty_for_io on each page in the range.
+ * Otherwise applications with the file mmap'd can wander in and change
+ * the page contents while we are compressing them.
+ *
+ * If the compression fails for any reason, we set the pages dirty again
+ * later on.
+ *
+ * Note that the remaining part is redirtied, the start pointer has
+ * moved, the end is the original one.
+ */
+ if (!redirty) {
+ extent_range_clear_dirty_for_io(&inode->vfs_inode, start, end);
+ redirty = 1;
+ }
- /* Compression level is applied here and only here */
- ret = btrfs_compress_pages(
- compress_type | (fs_info->compress_level << 4),
- mapping, start,
- pages,
- &nr_pages,
- &total_in,
- &total_compressed);
+ /* Compression level is applied here and only here */
+ ret = btrfs_compress_pages(compress_type |
+ (fs_info->compress_level << 4),
+ mapping, start, pages, &nr_pages, &total_in,
+ &total_compressed);
+ if (ret)
+ goto cont;
- if (!ret) {
- unsigned long offset = offset_in_page(total_compressed);
- struct page *page = pages[nr_pages - 1];
+ /*
+ * Zero the tail end of the last page, as we might be sending it down
+ * to disk.
+ */
+ poff = offset_in_page(total_compressed);
+ if (poff)
+ memzero_page(pages[nr_pages - 1], poff, PAGE_SIZE - poff);
+ will_compress = 1;
- /* zero the tail end of the last page, we might be
- * sending it down to disk
- */
- if (offset)
- memzero_page(page, offset, PAGE_SIZE - offset);
- will_compress = 1;
- }
- }
cont:
/*
* Check cow_file_range() for why we don't even try to create inline
- * extent for subpage case.
+ * extent for the subpage case.
*/
if (start == 0 && fs_info->sectorsize == PAGE_SIZE) {
/* lets try to make an inline extent */
@@ -1028,39 +1026,38 @@ static void compress_file_range(struct btrfs_work *work)
}
}
- if (will_compress) {
- /*
- * we aren't doing an inline extent round the compressed size
- * up to a block size boundary so the allocator does sane
- * things
- */
- total_compressed = ALIGN(total_compressed, blocksize);
+ if (!will_compress)
+ goto cleanup_and_bail_uncompressed;
- /*
- * one last check to make sure the compression is really a
- * win, compare the page count read with the blocks on disk,
- * compression must free at least one sector size
- */
- total_in = round_up(total_in, fs_info->sectorsize);
- if (total_compressed + blocksize <= total_in) {
- /*
- * The async work queues will take care of doing actual
- * allocation on disk for these compressed pages, and
- * will submit them to the elevator.
- */
- add_async_extent(async_chunk, start, total_in,
- total_compressed, pages, nr_pages,
- compress_type);
-
- if (start + total_in < end) {
- start += total_in;
- pages = NULL;
- cond_resched();
- goto again;
- }
- return;
- }
+ /*
+ * We aren't doing an inline extent. Round the compressed size up to a
+ * block size boundary so the allocator does sane things.
+ */
+ total_compressed = ALIGN(total_compressed, blocksize);
+
+ /*
+ * One last check to make sure the compression is really a win, compare
+ * the page count read with the blocks on disk, compression must free at
+ * least one sector.
+ */
+ total_in = round_up(total_in, fs_info->sectorsize);
+ if (total_compressed + blocksize > total_in)
+ goto cleanup_and_bail_uncompressed;
+
+ /*
+ * The async work queues will take care of doing actual allocation on
+ * disk for these compressed pages, and will submit the bios.
+ */
+ add_async_extent(async_chunk, start, total_in, total_compressed, pages,
+ nr_pages, compress_type);
+ if (start + total_in < end) {
+ start += total_in;
+ cond_resched();
+ goto again;
}
+ return;
+
+cleanup_and_bail_uncompressed:
if (pages) {
/*
* the compression code ran but failed to make things smaller,
@@ -1081,7 +1078,7 @@ static void compress_file_range(struct btrfs_work *work)
inode->flags |= BTRFS_INODE_NOCOMPRESS;
}
}
-cleanup_and_bail_uncompressed:
+
/*
* No compression, but we still need to write the pages in the file
* we've been given so far. redirty the locked page if it corresponds
--
2.39.2
