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authorEric Biggers <ebiggers@google.com>2019-05-20 09:29:39 -0700
committerEric Biggers <ebiggers@google.com>2019-05-28 10:27:52 -0700
commitd2d0727b1654e11563f181f4d3d48b9275514480 (patch)
treefca4761fc4cf02a31f43aac5ae86e5276bbc298b /fs/ext4
parentcd6c84d8f0cdc911df435bb075ba22ce3c605b07 (diff)
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fscrypt: simplify bounce page handling
Currently, bounce page handling for writes to encrypted files is unnecessarily complicated. A fscrypt_ctx is allocated along with each bounce page, page_private(bounce_page) points to this fscrypt_ctx, and fscrypt_ctx::w::control_page points to the original pagecache page. However, because writes don't use the fscrypt_ctx for anything else, there's no reason why page_private(bounce_page) can't just point to the original pagecache page directly. Therefore, this patch makes this change. In the process, it also cleans up the API exposed to filesystems that allows testing whether a page is a bounce page, getting the pagecache page from a bounce page, and freeing a bounce page. Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com> Signed-off-by: Eric Biggers <ebiggers@google.com>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/page-io.c36
1 files changed, 13 insertions, 23 deletions
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 4690618a92e9..13d5ecc0af03 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -66,9 +66,7 @@ static void ext4_finish_bio(struct bio *bio)
bio_for_each_segment_all(bvec, bio, iter_all) {
struct page *page = bvec->bv_page;
-#ifdef CONFIG_FS_ENCRYPTION
- struct page *data_page = NULL;
-#endif
+ struct page *bounce_page = NULL;
struct buffer_head *bh, *head;
unsigned bio_start = bvec->bv_offset;
unsigned bio_end = bio_start + bvec->bv_len;
@@ -78,13 +76,10 @@ static void ext4_finish_bio(struct bio *bio)
if (!page)
continue;
-#ifdef CONFIG_FS_ENCRYPTION
- if (!page->mapping) {
- /* The bounce data pages are unmapped. */
- data_page = page;
- fscrypt_pullback_bio_page(&page, false);
+ if (fscrypt_is_bounce_page(page)) {
+ bounce_page = page;
+ page = fscrypt_pagecache_page(bounce_page);
}
-#endif
if (bio->bi_status) {
SetPageError(page);
@@ -111,10 +106,7 @@ static void ext4_finish_bio(struct bio *bio)
bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
local_irq_restore(flags);
if (!under_io) {
-#ifdef CONFIG_FS_ENCRYPTION
- if (data_page)
- fscrypt_restore_control_page(data_page);
-#endif
+ fscrypt_free_bounce_page(bounce_page);
end_page_writeback(page);
}
}
@@ -415,7 +407,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
struct writeback_control *wbc,
bool keep_towrite)
{
- struct page *data_page = NULL;
+ struct page *bounce_page = NULL;
struct inode *inode = page->mapping->host;
unsigned block_start;
struct buffer_head *bh, *head;
@@ -479,10 +471,10 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
gfp_t gfp_flags = GFP_NOFS;
retry_encrypt:
- data_page = fscrypt_encrypt_page(inode, page, PAGE_SIZE, 0,
- page->index, gfp_flags);
- if (IS_ERR(data_page)) {
- ret = PTR_ERR(data_page);
+ bounce_page = fscrypt_encrypt_page(inode, page, PAGE_SIZE, 0,
+ page->index, gfp_flags);
+ if (IS_ERR(bounce_page)) {
+ ret = PTR_ERR(bounce_page);
if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
if (io->io_bio) {
ext4_io_submit(io);
@@ -491,7 +483,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
gfp_flags |= __GFP_NOFAIL;
goto retry_encrypt;
}
- data_page = NULL;
+ bounce_page = NULL;
goto out;
}
}
@@ -500,8 +492,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
do {
if (!buffer_async_write(bh))
continue;
- ret = io_submit_add_bh(io, inode,
- data_page ? data_page : page, bh);
+ ret = io_submit_add_bh(io, inode, bounce_page ?: page, bh);
if (ret) {
/*
* We only get here on ENOMEM. Not much else
@@ -517,8 +508,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
/* Error stopped previous loop? Clean up buffers... */
if (ret) {
out:
- if (data_page)
- fscrypt_restore_control_page(data_page);
+ fscrypt_free_bounce_page(bounce_page);
printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
redirty_page_for_writepage(wbc, page);
do {