Attachment 6511 Details for Bug 8175 – git-am fix for 3.6.0

[patch] git-am fix for 3.6.0

0001-Fix-bug-8175-smbd-deadlock.patch (text/plain), 5.74 KB, created by Jeremy Allison on 2011-06-01 19:16:11 UTC

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Creator: Jeremy Allison

Created: 2011-06-01 19:16:11 UTC

Size: 5.74 KB

patch

obsolete

>From 5a2b5b6cfed74e0e9c2965525995f64cdad7b7c9 Mon Sep 17 00:00:00 2001
>From: Jeremy Allison <jra@samba.org>
>Date: Wed, 1 Jun 2011 12:11:53 -0700
>Subject: [PATCH] Fix bug #8175 - smbd deadlock.
>
>Force the open operation (which is the expensive one anyway) to
>acquire and release locks in a way compatible with the more common
>do_lock check.
>
>Jeremy.
>---
> source3/smbd/open.c |   98 +++++++++++++++++++++++++++++++++++++--------------
> 1 files changed, 71 insertions(+), 27 deletions(-)
>
>diff --git a/source3/smbd/open.c b/source3/smbd/open.c
>index bb7e6c2..5c92880 100644
>--- a/source3/smbd/open.c
>+++ b/source3/smbd/open.c
>@@ -1055,18 +1055,8 @@ static bool delay_for_exclusive_oplocks(files_struct *fsp,
> 	return false;
> }
> 
>-static bool file_has_brlocks(files_struct *fsp)
>-{
>-	struct byte_range_lock *br_lck;
>-
>-	br_lck = brl_get_locks_readonly(fsp);
>-	if (!br_lck)
>-		return false;
>-
>-	return br_lck->num_locks > 0 ? true : false;
>-}
>-
> static void grant_fsp_oplock_type(files_struct *fsp,
>+				const struct byte_range_lock *br_lck,
> 				int oplock_request,
> 				bool got_level2_oplock,
> 				bool got_a_none_oplock)
>@@ -1084,7 +1074,7 @@ static void grant_fsp_oplock_type(files_struct *fsp,
> 		DEBUG(10,("grant_fsp_oplock_type: oplock type 0x%x on file %s\n",
> 			fsp->oplock_type, fsp_str_dbg(fsp)));
> 		return;
>-	} else if (lp_locking(fsp->conn->params) && file_has_brlocks(fsp)) {
>+	} else if (br_lck && br_lck->num_locks > 0) {
> 		DEBUG(10,("grant_fsp_oplock_type: file %s has byte range locks\n",
> 			fsp_str_dbg(fsp)));
> 		fsp->oplock_type = NO_OPLOCK;
>@@ -1562,6 +1552,55 @@ void remove_deferred_open_entry(struct file_id id, uint64_t mid,
> 	}
> }
> 
>+/****************************************************************
>+ Ensure we get the brlock lock followed by the share mode lock
>+ in the correct order to prevent deadlocks if other smbd's are
>+ using the brlock database on this file simultaneously with this open
>+ (that code also gets the locks in brlock -> share mode lock order).
>+****************************************************************/
>+
>+static bool acquire_ordered_locks(TALLOC_CTX *mem_ctx,
>+				files_struct *fsp,
>+				const struct file_id id,
>+				const char *connectpath,
>+				const struct smb_filename *smb_fname,
>+				const struct timespec *p_old_write_time,
>+				struct share_mode_lock **p_lck,
>+				struct byte_range_lock **p_br_lck)
>+{
>+	/* Ordering - we must get the br_lck for this
>+	   file before the share mode. */
>+	if (lp_locking(fsp->conn->params)) {
>+		*p_br_lck = brl_get_locks_readonly(fsp);
>+		if (*p_br_lck == NULL) {
>+			DEBUG(0, ("Could not get br_lock\n"));
>+			return false;
>+		}
>+		/* Note - we don't need to free the returned
>+		   br_lck explicitly as it was allocated on talloc_tos()
>+		   and so will be autofreed (and release the lock)
>+		   once the frame context disappears.
>+
>+		   If it was set to fsp->brlock_rec then it was
>+		   talloc_move'd to hang off the fsp pointer and
>+		   in this case is guarenteed to not be holding the
>+		   lock on the brlock database. */
>+	}
>+
>+	*p_lck = get_share_mode_lock(mem_ctx,
>+				id,
>+				connectpath,
>+				smb_fname,
>+				p_old_write_time);
>+
>+	if (*p_lck == NULL) {
>+		DEBUG(0, ("Could not get share mode lock\n"));
>+		TALLOC_FREE(*p_br_lck);
>+		return false;
>+	}
>+	return true;
>+}
>+
> /****************************************************************************
>  Open a file with a share mode. Passed in an already created files_struct *.
> ****************************************************************************/
>@@ -1906,6 +1945,7 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
> 	}
> 
> 	if (file_existed) {
>+		struct byte_range_lock *br_lck = NULL;
> 		struct share_mode_entry *batch_entry = NULL;
> 		struct share_mode_entry *exclusive_entry = NULL;
> 		bool got_level2_oplock = false;
>@@ -1914,12 +1954,14 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
> 		struct timespec old_write_time = smb_fname->st.st_ex_mtime;
> 		id = vfs_file_id_from_sbuf(conn, &smb_fname->st);
> 
>-		lck = get_share_mode_lock(talloc_tos(), id,
>-					  conn->connectpath,
>-					  smb_fname, &old_write_time);
>-
>-		if (lck == NULL) {
>-			DEBUG(0, ("Could not get share mode lock\n"));
>+		if (!acquire_ordered_locks(talloc_tos(),
>+					fsp,
>+					id,
>+					conn->connectpath,
>+					smb_fname,
>+					&old_write_time,
>+					&lck,
>+					&br_lck)) {
> 			return NT_STATUS_SHARING_VIOLATION;
> 		}
> 
>@@ -1973,6 +2015,7 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
> 		}
> 
> 		grant_fsp_oplock_type(fsp,
>+				br_lck,
>                                 oplock_request,
>                                 got_level2_oplock,
>                                 got_a_none_oplock);
>@@ -2136,6 +2179,7 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
> 	}
> 
> 	if (!file_existed) {
>+		struct byte_range_lock *br_lck = NULL;
> 		struct share_mode_entry *batch_entry = NULL;
> 		struct share_mode_entry *exclusive_entry = NULL;
> 		bool got_level2_oplock = false;
>@@ -2158,15 +2202,14 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
> 
> 		id = fsp->file_id;
> 
>-		lck = get_share_mode_lock(talloc_tos(), id,
>-					  conn->connectpath,
>-					  smb_fname, &old_write_time);
>-
>-		if (lck == NULL) {
>-			DEBUG(0, ("open_file_ntcreate: Could not get share "
>-				  "mode lock for %s\n",
>-				  smb_fname_str_dbg(smb_fname)));
>-			fd_close(fsp);
>+		if (!acquire_ordered_locks(talloc_tos(),
>+					fsp,
>+					id,
>+					conn->connectpath,
>+					smb_fname,
>+					&old_write_time,
>+					&lck,
>+					&br_lck)) {
> 			return NT_STATUS_SHARING_VIOLATION;
> 		}
> 
>@@ -2237,6 +2280,7 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
> 		}
> 
> 		grant_fsp_oplock_type(fsp,
>+				br_lck,
>                                 oplock_request,
>                                 got_level2_oplock,
>                                 got_a_none_oplock);
>-- 
>1.7.3.1
>

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vl: review+
ambi: review+

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Attachments on bug 8175: 6495 | 6511