[PATCH 2/3] ext3 reservation allow turn off for specifed file

[Mingming Cao]

Allow user shut down reservation-based allocation(using ioctl) on a specific file(e.g. for seeky random write).


---

 linux-2.6.9-rc4-mm1-ming/fs/ext3/balloc.c |   15 +++++++++++++--
 1 files changed, 13 insertions(+), 2 deletions(-)

diff -puN fs/ext3/balloc.c~ext3_shutdown_reservation_per-file fs/ext3/balloc.c
--- linux-2.6.9-rc4-mm1/fs/ext3/balloc.c~ext3_shutdown_reservation_per-file	2004-10-18 22:27:06.333698488 -0700
+++ linux-2.6.9-rc4-mm1-ming/fs/ext3/balloc.c	2004-10-18 22:34:52.825780912 -0700
@@ -1153,6 +1153,7 @@ int ext3_new_block(handle_t *handle, str
 	struct ext3_super_block *es;
 	struct ext3_sb_info *sbi;
 	struct reserve_window_node *my_rsv = NULL;
+	struct reserve_window_node *rsv = &EXT3_I(inode)->i_rsv_window;
 #ifdef EXT3FS_DEBUG
 	static int goal_hits, goal_attempts;
 #endif
@@ -1176,8 +1177,18 @@ int ext3_new_block(handle_t *handle, str
 	sbi = EXT3_SB(sb);
 	es = EXT3_SB(sb)->s_es;
 	ext3_debug("goal=%lu.\n", goal);
-	if (test_opt(sb, RESERVATION) && S_ISREG(inode->i_mode))
-		my_rsv = &EXT3_I(inode)->i_rsv_window;
+	/*
+	 * Allocate a block from reservation only when
+	 * filesystem is mounted with reservation(default,-o reservation), and
+	 * it's a regular file, and
+	 * the desired window size is greater than 0 (One could use ioctl
+	 * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
+	 * reservation on that particular file)
+	 */
+	if (test_opt(sb, RESERVATION) &&
+		S_ISREG(inode->i_mode) &&
+		(atomic_read(&rsv->rsv_goal_size) > 0))
+		my_rsv = rsv;
 	if (!ext3_has_free_blocks(sbi)) {
 		*errp = -ENOSPC;
 		goto out;

_

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