| Message ID | 20240103145935.384404-5-dhowells@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | netfs, cachefiles, 9p: Additional patches | expand |
David Howells wrote on Wed, Jan 03, 2024 at 02:59:28PM +0000: > Always update remote_i_size in v9fs_stat2inode*() if the size is available, > even if we are asked not to update i_isize Sorry -- hold on for this patch, let's drop it for now and take it more slowly through next cycle. I had mostly forgotten about V9FS_STAT2INODE_KEEP_ISIZE and not paying enough attention yesterday evening, but it's not innocent -- I assume netfs will do the right thing if we update the *remote* i_size when there is cached data, but the inode's i_size cannot be updated as easily. It's hard to notice because the comment got split in 5e3cc1ee1405a7 ("9p: use inode->i_lock to protect i_size_write() under 32-bit"), but v9fs_refresh_inode* still have it: /* * We don't want to refresh inode->i_size, * because we may have cached data */ I assume refreshing i_size at a bad time would act like a truncation of cached memory. (To answer the other thread's comment that v9fs_i_size_write is useless; it's far from obvious enough but I'm afraid it is needed: - include/linux/fs.h has a comment saying i_size_write does need locking around it for 32bit to avoid breaking i_size_seqcount; that's still true in today's tree. - we could use any lock as long as it's coherent within the 9p subsystem, but we don't need a whole mutex so i_lock it is.)
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c index 3505227e1704..aa3a77bb5e86 100644 --- a/fs/9p/vfs_inode_dotl.c +++ b/fs/9p/vfs_inode_dotl.c @@ -684,10 +684,10 @@ v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode, mode |= inode->i_mode & ~S_IALLUGO; inode->i_mode = mode; } - if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE) && - stat->st_result_mask & P9_STATS_SIZE) { + if (stat->st_result_mask & P9_STATS_SIZE) { v9inode->netfs.remote_i_size = stat->st_size; - v9fs_i_size_write(inode, stat->st_size); + if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE)) + v9fs_i_size_write(inode, stat->st_size); } if (stat->st_result_mask & P9_STATS_BLOCKS) inode->i_blocks = stat->st_blocks;
Always update remote_i_size in v9fs_stat2inode*() if the size is available, even if we are asked not to update i_isize Suggested-by: Dominique Martinet <asmadeus@codewreck.org> Link: https://lore.kernel.org/r/ZZVctju5TEjS218p@codewreck.org/ Signed-off-by: David Howells <dhowells@redhat.com> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: v9fs@lists.linux.dev cc: linux-cachefs@redhat.com cc: linux-fsdevel@vger.kernel.org --- fs/9p/vfs_inode_dotl.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)