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Date: Fri, 29 Oct 2021 15:09:52 +0100 From: David Howells <dhowells@...hat.com> To: Trond Myklebust <trondmy@...merspace.com>, Anna Schumaker <anna.schumaker@...app.com>, Steve French <sfrench@...ba.org>, Dominique Martinet <asmadeus@...ewreck.org> Cc: dhowells@...hat.com, Jeff Layton <jlayton@...hat.com>, Matthew Wilcox <willy@...radead.org>, Alexander Viro <viro@...iv.linux.org.uk>, Linus Torvalds <torvalds@...ux-foundation.org>, linux-cachefs@...hat.com, linux-afs@...ts.infradead.org, linux-nfs@...r.kernel.org, linux-cifs@...r.kernel.org, ceph-devel@...r.kernel.org, v9fs-developer@...ts.sourceforge.net, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH v4 03/10] cachefiles: Always indicate we should fill a post-EOF page with zeros In cachefiles_prepare_read(), always indicate to the netfs lib that a page beyond the EOF should be filled with zeros, even if we don't have a cache file attached because it's still being created. This avoids confusion in netfs_rreq_prepare_read() where it sees source == NETFS_DOWNLOAD_FROM_SERVER, where it consequently sees the read after the EOF getting reduced to 0 size and thus triggers the WARN_ON and marking the read invalid. Also don't try to check for data if there's a flag set indicating we don't yet have anything stored in the cache. Signed-off-by: David Howells <dhowells@...hat.com> --- fs/cachefiles/io.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c index 08b3183e0dce..dbc1c4421116 100644 --- a/fs/cachefiles/io.c +++ b/fs/cachefiles/io.c @@ -273,6 +273,7 @@ static enum netfs_read_source cachefiles_prepare_read(struct netfs_read_subreque struct cachefiles_cache *cache; const struct cred *saved_cred; struct file *file = subreq->rreq->cache_resources.cache_priv2; + enum netfs_read_source ret = NETFS_DOWNLOAD_FROM_SERVER; loff_t off, to; _enter("%zx @%llx/%llx", subreq->len, subreq->start, i_size); @@ -281,19 +282,24 @@ static enum netfs_read_source cachefiles_prepare_read(struct netfs_read_subreque cache = container_of(object->fscache.cache, struct cachefiles_cache, cache); - if (!file) - goto cache_fail_nosec; + cachefiles_begin_secure(cache, &saved_cred); - if (subreq->start >= i_size) - return NETFS_FILL_WITH_ZEROES; + if (subreq->start >= i_size) { + ret = NETFS_FILL_WITH_ZEROES; + goto out; + } - cachefiles_begin_secure(cache, &saved_cred); + if (!file) + goto out; + + if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->fscache.cookie->flags)) + goto download_and_store; off = vfs_llseek(file, subreq->start, SEEK_DATA); if (off < 0 && off >= (loff_t)-MAX_ERRNO) { if (off == (loff_t)-ENXIO) goto download_and_store; - goto cache_fail; + goto out; } if (off >= subreq->start + subreq->len) @@ -307,7 +313,7 @@ static enum netfs_read_source cachefiles_prepare_read(struct netfs_read_subreque to = vfs_llseek(file, subreq->start, SEEK_HOLE); if (to < 0 && to >= (loff_t)-MAX_ERRNO) - goto cache_fail; + goto out; if (to < subreq->start + subreq->len) { if (subreq->start + subreq->len >= i_size) @@ -317,16 +323,15 @@ static enum netfs_read_source cachefiles_prepare_read(struct netfs_read_subreque subreq->len = to - subreq->start; } - cachefiles_end_secure(cache, saved_cred); - return NETFS_READ_FROM_CACHE; + ret = NETFS_READ_FROM_CACHE; + goto out; download_and_store: if (cachefiles_has_space(cache, 0, (subreq->len + PAGE_SIZE - 1) / PAGE_SIZE) == 0) __set_bit(NETFS_SREQ_WRITE_TO_CACHE, &subreq->flags); -cache_fail: +out: cachefiles_end_secure(cache, saved_cred); -cache_fail_nosec: - return NETFS_DOWNLOAD_FROM_SERVER; + return ret; } /*
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