6.6-stable review patch. If anyone has any objections, please let me know.
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From: Paulo Alcantara pc@manguebit.org
[ Upstream commit d84291fc7453df7881a970716f8256273aca5747 ]
Besides sending the rename request to the server, the rename process also involves closing any deferred close, waiting for outstanding I/O to complete as well as marking all existing open handles as deleted to prevent them from deferring closes, which increases the race window for potential concurrent opens on the target file.
Fix this by unhashing the dentry in advance to prevent any concurrent opens on the target.
Signed-off-by: Paulo Alcantara (Red Hat) pc@manguebit.org Reviewed-by: David Howells dhowells@redhat.com Cc: Al Viro viro@zeniv.linux.org.uk Cc: linux-cifs@vger.kernel.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/smb/client/inode.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c index df01029918fd4..6c16c4f34d882 100644 --- a/fs/smb/client/inode.c +++ b/fs/smb/client/inode.c @@ -2379,6 +2379,7 @@ cifs_rename2(struct mnt_idmap *idmap, struct inode *source_dir, struct cifs_sb_info *cifs_sb; struct tcon_link *tlink; struct cifs_tcon *tcon; + bool rehash = false; unsigned int xid; int rc, tmprc; int retry_count = 0; @@ -2394,6 +2395,17 @@ cifs_rename2(struct mnt_idmap *idmap, struct inode *source_dir, if (unlikely(cifs_forced_shutdown(cifs_sb))) return -EIO;
+ /* + * Prevent any concurrent opens on the target by unhashing the dentry. + * VFS already unhashes the target when renaming directories. + */ + if (d_is_positive(target_dentry) && !d_is_dir(target_dentry)) { + if (!d_unhashed(target_dentry)) { + d_drop(target_dentry); + rehash = true; + } + } + tlink = cifs_sb_tlink(cifs_sb); if (IS_ERR(tlink)) return PTR_ERR(tlink); @@ -2433,6 +2445,8 @@ cifs_rename2(struct mnt_idmap *idmap, struct inode *source_dir, } }
+ if (!rc) + rehash = false; /* * No-replace is the natural behavior for CIFS, so skip unlink hacks. */ @@ -2491,12 +2505,16 @@ cifs_rename2(struct mnt_idmap *idmap, struct inode *source_dir, goto cifs_rename_exit; rc = cifs_do_rename(xid, source_dentry, from_name, target_dentry, to_name); + if (!rc) + rehash = false; }
/* force revalidate to go get info when needed */ CIFS_I(source_dir)->time = CIFS_I(target_dir)->time = 0;
cifs_rename_exit: + if (rehash) + d_rehash(target_dentry); kfree(info_buf_source); free_dentry_path(page2); free_dentry_path(page1);