2013/10/30 Jeff Layton <jlayton@xxxxxxxxxx>:
> On Wed, 30 Oct 2013 11:46:22 +0400
> Pavel Shilovsky <piastry@xxxxxxxxxxx> wrote:
>
>> 2013/10/29 Jeff Layton <jlayton@xxxxxxxxxx>:
>> > On Wed, 23 Oct 2013 18:42:54 +0400
>> > Pavel Shilovsky <piastry@xxxxxxxxxxx> wrote:
>> >
>> >> I created a slightly tested patch below but can't test with deduplicated files now.
>> >>
>> >> Joao, can you check if it fixes your problem, please?
>> >>
>> >> --------------------------------------------------------------------------
>> >>
>> >> Distinguish reparse point types into two groups:
>> >> 1) that can be accessed directly through a reparse point
>> >> (junctions, deduplicated files, NFS symlinks);
>> >> 2) that need to be processed manually (Windows symbolic links, DFS).
>> >>
>> >> In this case we map only Windows symbolic links to Unix ones.
>> >>
>> >> Signed-off-by: Pavel Shilovsky <piastry@xxxxxxxxxxx>
>> >> ---
>> >> fs/cifs/cifsglob.h | 2 +-
>> >> fs/cifs/inode.c | 23 +++++++++++++----------
>> >> fs/cifs/readdir.c | 40 ++++++++--------------------------------
>> >> fs/cifs/smb1ops.c | 27 ++++++++++++++++++++++-----
>> >> fs/cifs/smb2inode.c | 15 +++++++++++----
>> >> fs/cifs/smb2proto.h | 2 +-
>> >> 6 files changed, 56 insertions(+), 53 deletions(-)
>> >>
>> >> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
>> >> index a67cf12..b688f2b 100644
>> >> --- a/fs/cifs/cifsglob.h
>> >> +++ b/fs/cifs/cifsglob.h
>> >> @@ -261,7 +261,7 @@ struct smb_version_operations {
>> >> /* query path data from the server */
>> >> int (*query_path_info)(const unsigned int, struct cifs_tcon *,
>> >> struct cifs_sb_info *, const char *,
>> >> - FILE_ALL_INFO *, bool *);
>> >> + FILE_ALL_INFO *, bool *, bool *);
>> >> /* query file data from the server */
>> >> int (*query_file_info)(const unsigned int, struct cifs_tcon *,
>> >> struct cifs_fid *, FILE_ALL_INFO *);
>> >> diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
>> >> index 867b7cd..36f9ebb 100644
>> >> --- a/fs/cifs/inode.c
>> >> +++ b/fs/cifs/inode.c
>> >> @@ -542,7 +542,8 @@ static int cifs_sfu_mode(struct cifs_fattr *fattr, const unsigned char *path,
>> >> /* Fill a cifs_fattr struct with info from FILE_ALL_INFO */
>> >> static void
>> >> cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
>> >> - struct cifs_sb_info *cifs_sb, bool adjust_tz)
>> >> + struct cifs_sb_info *cifs_sb, bool adjust_tz,
>> >> + bool symlink)
>> >> {
>> >> struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
>> >>
>> >> @@ -569,7 +570,11 @@ cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
>> >> fattr->cf_createtime = le64_to_cpu(info->CreationTime);
>> >>
>> >> fattr->cf_nlink = le32_to_cpu(info->NumberOfLinks);
>> >> - if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
>> >> +
>> >> + if (symlink) {
>> >> + fattr->cf_mode = S_IFLNK;
>> >> + fattr->cf_dtype = DT_LNK;
>> >> + } else if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
>> >> fattr->cf_mode = S_IFDIR | cifs_sb->mnt_dir_mode;
>> >> fattr->cf_dtype = DT_DIR;
>> >> /*
>> >> @@ -578,10 +583,6 @@ cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
>> >> */
>> >> if (!tcon->unix_ext)
>> >> fattr->cf_flags |= CIFS_FATTR_UNKNOWN_NLINK;
>> >> - } else if (fattr->cf_cifsattrs & ATTR_REPARSE) {
>> >> - fattr->cf_mode = S_IFLNK;
>> >> - fattr->cf_dtype = DT_LNK;
>> >> - fattr->cf_nlink = le32_to_cpu(info->NumberOfLinks);
>> >> } else {
>> >> fattr->cf_mode = S_IFREG | cifs_sb->mnt_file_mode;
>> >> fattr->cf_dtype = DT_REG;
>> >> @@ -626,7 +627,8 @@ cifs_get_file_info(struct file *filp)
>> >> rc = server->ops->query_file_info(xid, tcon, &cfile->fid, &find_data);
>> >> switch (rc) {
>> >> case 0:
>> >> - cifs_all_info_to_fattr(&fattr, &find_data, cifs_sb, false);
>> >> + cifs_all_info_to_fattr(&fattr, &find_data, cifs_sb, false,
>> >> + false);
>> >> break;
>> >> case -EREMOTE:
>> >> cifs_create_dfs_fattr(&fattr, inode->i_sb);
>> >> @@ -673,6 +675,7 @@ cifs_get_inode_info(struct inode **inode, const char *full_path,
>> >> bool adjust_tz = false;
>> >> struct cifs_fattr fattr;
>> >> struct cifs_search_info *srchinf = NULL;
>> >> + bool symlink = false;
>> >>
>> >> tlink = cifs_sb_tlink(cifs_sb);
>> >> if (IS_ERR(tlink))
>> >> @@ -702,12 +705,12 @@ cifs_get_inode_info(struct inode **inode, const char *full_path,
>> >> }
>> >> data = (FILE_ALL_INFO *)buf;
>> >> rc = server->ops->query_path_info(xid, tcon, cifs_sb, full_path,
>> >> - data, &adjust_tz);
>> >> + data, &adjust_tz, &symlink);
>> >> }
>> >>
>> >> if (!rc) {
>> >> - cifs_all_info_to_fattr(&fattr, (FILE_ALL_INFO *)data, cifs_sb,
>> >> - adjust_tz);
>> >> + cifs_all_info_to_fattr(&fattr, data, cifs_sb, adjust_tz,
>> >> + symlink);
>> >> } else if (rc == -EREMOTE) {
>> >> cifs_create_dfs_fattr(&fattr, sb);
>> >> rc = 0;
>> >> diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
>> >> index 53a75f3..5940eca 100644
>> >> --- a/fs/cifs/readdir.c
>> >> +++ b/fs/cifs/readdir.c
>> >> @@ -134,22 +134,6 @@ out:
>> >> dput(dentry);
>> >> }
>> >>
>> >> -/*
>> >> - * Is it possible that this directory might turn out to be a DFS referral
>> >> - * once we go to try and use it?
>> >> - */
>> >> -static bool
>> >> -cifs_dfs_is_possible(struct cifs_sb_info *cifs_sb)
>> >> -{
>> >> -#ifdef CONFIG_CIFS_DFS_UPCALL
>> >> - struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
>> >> -
>> >> - if (tcon->Flags & SMB_SHARE_IS_IN_DFS)
>> >> - return true;
>> >> -#endif
>> >> - return false;
>> >> -}
>> >> -
>> >> static void
>> >> cifs_fill_common_info(struct cifs_fattr *fattr, struct cifs_sb_info *cifs_sb)
>> >> {
>> >> @@ -159,27 +143,19 @@ cifs_fill_common_info(struct cifs_fattr *fattr, struct cifs_sb_info *cifs_sb)
>> >> if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
>> >> fattr->cf_mode = S_IFDIR | cifs_sb->mnt_dir_mode;
>> >> fattr->cf_dtype = DT_DIR;
>> >> - /*
>> >> - * Windows CIFS servers generally make DFS referrals look
>> >> - * like directories in FIND_* responses with the reparse
>> >> - * attribute flag also set (since DFS junctions are
>> >> - * reparse points). We must revalidate at least these
>> >> - * directory inodes before trying to use them (if
>> >> - * they are DFS we will get PATH_NOT_COVERED back
>> >> - * when queried directly and can then try to connect
>> >> - * to the DFS target)
>> >> - */
>> >> - if (cifs_dfs_is_possible(cifs_sb) &&
>> >> - (fattr->cf_cifsattrs & ATTR_REPARSE))
>> >> - fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;
>> >> - } else if (fattr->cf_cifsattrs & ATTR_REPARSE) {
>> >> - fattr->cf_mode = S_IFLNK;
>> >> - fattr->cf_dtype = DT_LNK;
>> >> } else {
>> >> fattr->cf_mode = S_IFREG | cifs_sb->mnt_file_mode;
>> >> fattr->cf_dtype = DT_REG;
>> >> }
>> >>
>> >> + /*
>> >> + * We need to revalidate it further to make a decision about whether it
>> >> + * is a symbolic link, DFS referral or a reparse point with a direct
>> >> + * access like junctions, deduplicated files, NFS symlinks.
>> >> + */
>> >> + if (fattr->cf_cifsattrs & ATTR_REPARSE)
>> >> + fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;
>> >> +
>> >> /* non-unix readdir doesn't provide nlink */
>> >> fattr->cf_flags |= CIFS_FATTR_UNKNOWN_NLINK;
>> >>
>> >> diff --git a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c
>> >> index ea99efe..3bb41cf 100644
>> >> --- a/fs/cifs/smb1ops.c
>> >> +++ b/fs/cifs/smb1ops.c
>> >> @@ -534,26 +534,43 @@ cifs_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,
>> >> static int
>> >> cifs_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
>> >> struct cifs_sb_info *cifs_sb, const char *full_path,
>> >> - FILE_ALL_INFO *data, bool *adjustTZ)
>> >> + FILE_ALL_INFO *data, bool *adjustTZ, bool *symlink)
>> >> {
>> >> int rc;
>> >> + int oplock = 0;
>> >> + __u16 netfid;
>> >> +
>> >> + rc = CIFSSMBOpen(xid, tcon, full_path, FILE_OPEN, FILE_READ_ATTRIBUTES,
>> >> + 0, &netfid, &oplock, NULL, cifs_sb->local_nls,
>> >> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
>> >> + if (rc == -EOPNOTSUPP) {
>> >> + *symlink = true;
>> >> + /* Failed on a symbolic link - query a reparse point info */
>> >> + rc = CIFSSMBOpen(xid, tcon, full_path, FILE_OPEN,
>> >> + FILE_READ_ATTRIBUTES, OPEN_REPARSE_POINT,
>> >> + &netfid, &oplock, NULL, cifs_sb->local_nls,
>> >> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
>> >> + }
>> >> +
>> >> + if (!rc) {
>> >> + rc = CIFSSMBQFileInfo(xid, tcon, netfid, data);
>> >> + CIFSSMBClose(xid, tcon, netfid);
>> >> + }
>> >
>> > Blech...
>> >
>> > So basically for any normal, non-symlink file you'll end up breaking
>> > any oplocks that might be held just by stat()'ing it? I sincerely hope
>> > there's a better way to solve this problem...
>> >
>>
>> No, we don't break any oplocks/leases here. Open with READ_ATTRIBUTES
>> access doesn't force the server to break oplocks. Note, that SMB2.0
>> protocol has been already doing stat with open-query-close mechanism
>> that cause no influence to oplocks/leases held by other clients.
>>
>> Citing MSDN (http://msdn.microsoft.com/en-us/library/windows/hardware/ff548639(v=vs.85).aspx):
>> "Note When processing IRP_MJ_CREATE for any oplock, if the desired
>> access contains nothing other than FILE_READ_ATTRIBUTES,
>> FILE_WRITE_ATTRIBUTES, or SYNCHRONIZE, the oplock does not break
>> unless FILE_RESERVE_OPFILTER is specified."
>>
>
> That's good at least, but it is still ugly. Plus, with this change will
> triple the number of round trips to the server, which will cause
> performance issues. I think you really want to avoid doing this unless
> you properly redesign this to use a compound.
While I agree with merging these three commands into a compound
request, I don't think that we should add it during the stable phase.
The approach proposed by this patch will bring a performance penalty,
of course, but it will be only on non-Unix shares with an application
doing 'stat' on many files.
Another possibility is to query file attributes with QpathInfo and
check if it's a reparse point. If no - return as usual. If yes - do
open-close to determine if the reparse point is symbolic link or not.
In this case we will not get a performance penalty for normal files
but will use 3 commands for every reparse points.
--
Best regards,
Pavel Shilovsky.
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