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authorTakashi Sato <t-sato@yk.jp.nec.com>2009-01-09 19:40:58 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-09 19:54:42 -0500
commitc4be0c1dc4cdc37b175579be1460f15ac6495e9a (patch)
tree716ea88318211ed27cadcebda0fd85c1f8246edb /fs/gfs2/ops_super.c
parent69347a236b22c3962ea812511495e502dedfd50c (diff)
filesystem freeze: add error handling of write_super_lockfs/unlockfs
Currently, ext3 in mainline Linux doesn't have the freeze feature which suspends write requests. So, we cannot take a backup which keeps the filesystem's consistency with the storage device's features (snapshot and replication) while it is mounted. In many case, a commercial filesystem (e.g. VxFS) has the freeze feature and it would be used to get the consistent backup. If Linux's standard filesystem ext3 has the freeze feature, we can do it without a commercial filesystem. So I have implemented the ioctls of the freeze feature. I think we can take the consistent backup with the following steps. 1. Freeze the filesystem with the freeze ioctl. 2. Separate the replication volume or create the snapshot with the storage device's feature. 3. Unfreeze the filesystem with the unfreeze ioctl. 4. Take the backup from the separated replication volume or the snapshot. This patch: VFS: Changed the type of write_super_lockfs and unlockfs from "void" to "int" so that they can return an error. Rename write_super_lockfs and unlockfs of the super block operation freeze_fs and unfreeze_fs to avoid a confusion. ext3, ext4, xfs, gfs2, jfs: Changed the type of write_super_lockfs and unlockfs from "void" to "int" so that write_super_lockfs returns an error if needed, and unlockfs always returns 0. reiserfs: Changed the type of write_super_lockfs and unlockfs from "void" to "int" so that they always return 0 (success) to keep a current behavior. Signed-off-by: Takashi Sato <t-sato@yk.jp.nec.com> Signed-off-by: Masayuki Hamaguchi <m-hamaguchi@ys.jp.nec.com> Cc: <xfs-masters@oss.sgi.com> Cc: <linux-ext4@vger.kernel.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Alasdair G Kergon <agk@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/gfs2/ops_super.c')
-rw-r--r--fs/gfs2/ops_super.c16
1 files changed, 9 insertions, 7 deletions
diff --git a/fs/gfs2/ops_super.c b/fs/gfs2/ops_super.c
index 777783deddcb..320323d03479 100644
--- a/fs/gfs2/ops_super.c
+++ b/fs/gfs2/ops_super.c
@@ -211,18 +211,18 @@ static int gfs2_sync_fs(struct super_block *sb, int wait)
211} 211}
212 212
213/** 213/**
214 * gfs2_write_super_lockfs - prevent further writes to the filesystem 214 * gfs2_freeze - prevent further writes to the filesystem
215 * @sb: the VFS structure for the filesystem 215 * @sb: the VFS structure for the filesystem
216 * 216 *
217 */ 217 */
218 218
219static void gfs2_write_super_lockfs(struct super_block *sb) 219static int gfs2_freeze(struct super_block *sb)
220{ 220{
221 struct gfs2_sbd *sdp = sb->s_fs_info; 221 struct gfs2_sbd *sdp = sb->s_fs_info;
222 int error; 222 int error;
223 223
224 if (test_bit(SDF_SHUTDOWN, &sdp->sd_flags)) 224 if (test_bit(SDF_SHUTDOWN, &sdp->sd_flags))
225 return; 225 return -EINVAL;
226 226
227 for (;;) { 227 for (;;) {
228 error = gfs2_freeze_fs(sdp); 228 error = gfs2_freeze_fs(sdp);
@@ -242,17 +242,19 @@ static void gfs2_write_super_lockfs(struct super_block *sb)
242 fs_err(sdp, "retrying...\n"); 242 fs_err(sdp, "retrying...\n");
243 msleep(1000); 243 msleep(1000);
244 } 244 }
245 return 0;
245} 246}
246 247
247/** 248/**
248 * gfs2_unlockfs - reallow writes to the filesystem 249 * gfs2_unfreeze - reallow writes to the filesystem
249 * @sb: the VFS structure for the filesystem 250 * @sb: the VFS structure for the filesystem
250 * 251 *
251 */ 252 */
252 253
253static void gfs2_unlockfs(struct super_block *sb) 254static int gfs2_unfreeze(struct super_block *sb)
254{ 255{
255 gfs2_unfreeze_fs(sb->s_fs_info); 256 gfs2_unfreeze_fs(sb->s_fs_info);
257 return 0;
256} 258}
257 259
258/** 260/**
@@ -688,8 +690,8 @@ const struct super_operations gfs2_super_ops = {
688 .put_super = gfs2_put_super, 690 .put_super = gfs2_put_super,
689 .write_super = gfs2_write_super, 691 .write_super = gfs2_write_super,
690 .sync_fs = gfs2_sync_fs, 692 .sync_fs = gfs2_sync_fs,
691 .write_super_lockfs = gfs2_write_super_lockfs, 693 .freeze_fs = gfs2_freeze,
692 .unlockfs = gfs2_unlockfs, 694 .unfreeze_fs = gfs2_unfreeze,
693 .statfs = gfs2_statfs, 695 .statfs = gfs2_statfs,
694 .remount_fs = gfs2_remount_fs, 696 .remount_fs = gfs2_remount_fs,
695 .clear_inode = gfs2_clear_inode, 697 .clear_inode = gfs2_clear_inode,