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Message-Id: <1304959308-11122-20-git-send-email-amir73il@users.sourceforge.net>
Date: Mon, 9 May 2011 19:41:37 +0300
From: amir73il@...rs.sourceforge.net
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, Amir Goldstein <amir73il@...rs.sf.net>,
Yongqiang Yang <xiaoqiangnk@...il.com>
Subject: [PATCH RFC 19/30] ext4: snapshot control - reserve disk space for snapshot
From: Amir Goldstein <amir73il@...rs.sf.net>
Ensure there is enough disk space for snapshot file future use.
Reserve disk space on snapshot take based on file system overhead
size, number of directories and number of blocks/inodes in use.
Signed-off-by: Amir Goldstein <amir73il@...rs.sf.net>
Signed-off-by: Yongqiang Yang <xiaoqiangnk@...il.com>
---
fs/ext4/balloc.c | 25 +++++++++++++++++++++++++
fs/ext4/ext4.h | 2 ++
fs/ext4/mballoc.c | 6 ++++++
fs/ext4/super.c | 16 +++++++++++++++-
4 files changed, 48 insertions(+), 1 deletions(-)
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 350f502..7d22e50 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -370,6 +370,8 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
static int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
{
s64 free_blocks, dirty_blocks, root_blocks;
+ ext4_fsblk_t snapshot_r_blocks;
+ handle_t *handle = journal_current_handle();
struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
@@ -377,6 +379,29 @@ static int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
dirty_blocks = percpu_counter_read_positive(dbc);
root_blocks = ext4_r_blocks_count(sbi->s_es);
+ if (ext4_snapshot_active(sbi)) {
+ if (unlikely(free_blocks < (nblocks + dirty_blocks)))
+ /* sorry, but we're really out of space */
+ return 0;
+ if (handle && unlikely(IS_COWING(handle)))
+ /* any available space may be used by COWing task */
+ return 1;
+ /* reserve blocks for active snapshot */
+ snapshot_r_blocks =
+ le64_to_cpu(sbi->s_es->s_snapshot_r_blocks_count);
+ /*
+ * The last snapshot_r_blocks are reserved for active snapshot
+ * and may not be allocated even by root.
+ */
+ if (free_blocks < (nblocks + dirty_blocks + snapshot_r_blocks))
+ return 0;
+ /*
+ * Mortal users must reserve blocks for both snapshot and
+ * root user.
+ */
+ root_blocks += snapshot_r_blocks;
+ }
+
if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
EXT4_FREEBLOCKS_WATERMARK) {
free_blocks = percpu_counter_sum_positive(fbc);
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index c04a031..884033f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1974,6 +1974,8 @@ extern __le16 ext4_group_desc_csum(struct ext4_sb_info *sbi, __u32 group,
struct ext4_group_desc *gdp);
extern int ext4_group_desc_csum_verify(struct ext4_sb_info *sbi, __u32 group,
struct ext4_group_desc *gdp);
+struct kstatfs;
+extern int ext4_statfs_sb(struct super_block *sb, struct kstatfs *buf);
static inline ext4_fsblk_t ext4_blocks_count(struct ext4_super_block *es)
{
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index d43f493..4813b15 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4290,10 +4290,16 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
return 0;
}
reserv_blks = ar->len;
+ if (unlikely(ar->flags & EXT4_MB_HINT_COWING)) {
+ /* don't fail when allocating blocks for COW */
+ dquot_alloc_block_nofail(ar->inode, ar->len);
+ goto nofail;
+ }
while (ar->len && dquot_alloc_block(ar->inode, ar->len)) {
ar->flags |= EXT4_MB_HINT_NOPREALLOC;
ar->len--;
}
+nofail:
inquota = ar->len;
if (ar->len == 0) {
*errp = -EDQUOT;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index d26831a..a768b63 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4464,7 +4464,11 @@ restore_opts:
static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf)
{
- struct super_block *sb = dentry->d_sb;
+ return ext4_statfs_sb(dentry->d_sb, buf);
+}
+
+int ext4_statfs_sb(struct super_block *sb, struct kstatfs *buf)
+{
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct ext4_super_block *es = sbi->s_es;
u64 fsid;
@@ -4516,6 +4520,16 @@ static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf)
buf->f_bavail = buf->f_bfree - ext4_r_blocks_count(es);
if (buf->f_bfree < ext4_r_blocks_count(es))
buf->f_bavail = 0;
+ if (ext4_snapshot_active(sbi)) {
+ if (buf->f_bfree < ext4_r_blocks_count(es) +
+ le64_to_cpu(es->s_snapshot_r_blocks_count))
+ buf->f_bavail = 0;
+ else
+ buf->f_bavail -=
+ le64_to_cpu(es->s_snapshot_r_blocks_count);
+ }
+ buf->f_spare[0] = percpu_counter_sum_positive(&sbi->s_dirs_counter);
+ buf->f_spare[1] = sbi->s_overhead_last;
buf->f_files = le32_to_cpu(es->s_inodes_count);
buf->f_ffree = percpu_counter_sum_positive(&sbi->s_freeinodes_counter);
buf->f_namelen = EXT4_NAME_LEN;
--
1.7.0.4
--
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