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Diffstat (limited to 'fs/ext4/readpage.c')
-rw-r--r--fs/ext4/readpage.c42
1 files changed, 23 insertions, 19 deletions
diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index fef7755300c3..c1769afbf799 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -57,6 +57,7 @@ enum bio_post_read_step {
STEP_INITIAL = 0,
STEP_DECRYPT,
STEP_VERITY,
+ STEP_MAX,
};
struct bio_post_read_ctx {
@@ -106,10 +107,22 @@ static void verity_work(struct work_struct *work)
{
struct bio_post_read_ctx *ctx =
container_of(work, struct bio_post_read_ctx, work);
+ struct bio *bio = ctx->bio;
- fsverity_verify_bio(ctx->bio);
+ /*
+ * fsverity_verify_bio() may call readpages() again, and although verity
+ * will be disabled for that, decryption may still be needed, causing
+ * another bio_post_read_ctx to be allocated. So to guarantee that
+ * mempool_alloc() never deadlocks we must free the current ctx first.
+ * This is safe because verity is the last post-read step.
+ */
+ BUILD_BUG_ON(STEP_VERITY + 1 != STEP_MAX);
+ mempool_free(ctx, bio_post_read_ctx_pool);
+ bio->bi_private = NULL;
- bio_post_read_processing(ctx);
+ fsverity_verify_bio(bio);
+
+ __read_end_io(bio);
}
static void bio_post_read_processing(struct bio_post_read_ctx *ctx)
@@ -176,12 +189,11 @@ static inline bool ext4_need_verity(const struct inode *inode, pgoff_t idx)
idx < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
}
-static struct bio_post_read_ctx *get_bio_post_read_ctx(struct inode *inode,
- struct bio *bio,
- pgoff_t first_idx)
+static void ext4_set_bio_post_read_ctx(struct bio *bio,
+ const struct inode *inode,
+ pgoff_t first_idx)
{
unsigned int post_read_steps = 0;
- struct bio_post_read_ctx *ctx = NULL;
if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode))
post_read_steps |= 1 << STEP_DECRYPT;
@@ -190,14 +202,14 @@ static struct bio_post_read_ctx *get_bio_post_read_ctx(struct inode *inode,
post_read_steps |= 1 << STEP_VERITY;
if (post_read_steps) {
- ctx = mempool_alloc(bio_post_read_ctx_pool, GFP_NOFS);
- if (!ctx)
- return ERR_PTR(-ENOMEM);
+ /* Due to the mempool, this never fails. */
+ struct bio_post_read_ctx *ctx =
+ mempool_alloc(bio_post_read_ctx_pool, GFP_NOFS);
+
ctx->bio = bio;
ctx->enabled_steps = post_read_steps;
bio->bi_private = ctx;
}
- return ctx;
}
static inline loff_t ext4_readpage_limit(struct inode *inode)
@@ -358,24 +370,16 @@ int ext4_mpage_readpages(struct address_space *mapping,
bio = NULL;
}
if (bio == NULL) {
- struct bio_post_read_ctx *ctx;
-
/*
* bio_alloc will _always_ be able to allocate a bio if
* __GFP_DIRECT_RECLAIM is set, see bio_alloc_bioset().
*/
bio = bio_alloc(GFP_KERNEL,
min_t(int, nr_pages, BIO_MAX_PAGES));
- ctx = get_bio_post_read_ctx(inode, bio, page->index);
- if (IS_ERR(ctx)) {
- bio_put(bio);
- bio = NULL;
- goto set_error_page;
- }
+ ext4_set_bio_post_read_ctx(bio, inode, page->index);
bio_set_dev(bio, bdev);
bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
bio->bi_end_io = mpage_end_io;
- bio->bi_private = ctx;
bio_set_op_attrs(bio, REQ_OP_READ,
is_readahead ? REQ_RAHEAD : 0);
}