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cifs: fix dentry lookups in directory handle cache

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Get rid of any prefix paths in @path before lookup_positive_unlocked()
as it will call ->lookup() which already adds those prefix paths
through build_path_from_dentry().

This has caused a performance regression when mounting shares with a
prefix path where readdir(2) would end up retrying several times to
open bad directory names that contained duplicate prefix paths.

Fix this by skipping any prefix paths in @path before calling
lookup_positive_unlocked().

Fixes: e4029e072673 ("cifs: find and use the dentry for cached non-root directories also")
Cc: stable@vger.kernel.org # 6.1+
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara 2023-03-24 13:56:33 -03:00 committed by Steve French
parent 7e0e76d990
commit be4fde7981
1 changed files with 34 additions and 2 deletions
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36
fs/cifs/cached_dir.c
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@ -99,6 +99,23 @@ path_to_dentry(struct cifs_sb_info *cifs_sb, const char *path)
return dentry;
}
static const char *path_no_prefix(struct cifs_sb_info *cifs_sb,
const char *path)
{
size_t len = 0;
if (!*path)
return path;
if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH) &&
cifs_sb->prepath) {
len = strlen(cifs_sb->prepath) + 1;
if (unlikely(len > strlen(path)))
return ERR_PTR(-EINVAL);
}
return path + len;
}
/*
* Open the and cache a directory handle.
* If error then *cfid is not initialized.
@ -125,6 +142,7 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
struct dentry *dentry = NULL;
struct cached_fid *cfid;
struct cached_fids *cfids;
const char *npath;
if (tcon == NULL || tcon->cfids == NULL || tcon->nohandlecache ||
is_smb1_server(tcon->ses->server))
@ -160,6 +178,20 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
return 0;
}
/*
* Skip any prefix paths in @path as lookup_positive_unlocked() ends up
* calling ->lookup() which already adds those through
* build_path_from_dentry(). Also, do it earlier as we might reconnect
* below when trying to send compounded request and then potentially
* having a different prefix path (e.g. after DFS failover).
*/
npath = path_no_prefix(cifs_sb, path);
if (IS_ERR(npath)) {
rc = PTR_ERR(npath);
kfree(utf16_path);
return rc;
}
/*
* We do not hold the lock for the open because in case
* SMB2_open needs to reconnect.
@ -252,10 +284,10 @@ int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
(char *)&cfid->file_all_info))
cfid->file_all_info_is_valid = true;
if (!path[0])
if (!npath[0])
dentry = dget(cifs_sb->root);
else {
dentry = path_to_dentry(cifs_sb, path);
dentry = path_to_dentry(cifs_sb, npath);
if (IS_ERR(dentry)) {
rc = -ENOENT;
goto oshr_free;