cachefiles: Fix incorrect length to fallocate()

When cachefiles_shorten_object() calls fallocate() to shape the cache
file to match the DIO size, it passes the total file size it wants to
achieve, not the amount of zeros that should be inserted.  Since this is
meant to preallocate that amount of storage for the file, it can cause
the cache to fill up the disk and hit ENOSPC.

Fix this by passing the length actually required to go from the current
EOF to the desired EOF.

Fixes: 7623ed6772 ("cachefiles: Implement cookie resize for truncate")
Reported-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/164630854858.3665356.17419701804248490708.stgit@warthog.procyon.org.uk # v1
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Howells 2022-03-03 13:05:18 +00:00 committed by Linus Torvalds
parent b949c21fc2
commit b08968f196

View File

@ -254,7 +254,7 @@ static bool cachefiles_shorten_object(struct cachefiles_object *object,
ret = cachefiles_inject_write_error();
if (ret == 0)
ret = vfs_fallocate(file, FALLOC_FL_ZERO_RANGE,
new_size, dio_size);
new_size, dio_size - new_size);
if (ret < 0) {
trace_cachefiles_io_error(object, file_inode(file), ret,
cachefiles_trace_fallocate_error);