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Date: Wed, 23 Jan 2019 10:32:45 -0800
From: harshadshirwadkar@...il.com
To: umka@...udlinux.com, linux-ext4@...r.kernel.org
Cc: Harshad Shirwadkar <harshadshirwadkar@...il.com>
Subject: [PATCH] ext4: shrink directory when last block is empty
From: Harshad Shirwadkar <harshadshirwadkar@...il.com>
This patch is the first step towards shrinking htree based directories
when files are deleted. We truncate directory inode when a directory
entry removal causes last directory block to be empty. This patch just
removes the last block. We may end up in a situation where many
intermediate dirent blocks in directory inode are empty. Removing
those blocks would be handled later.
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@...il.com>
---
fs/ext4/namei.c | 130 ++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 109 insertions(+), 21 deletions(-)
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 2a4c25c4681d..79cb88ba898a 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -273,7 +273,8 @@ static int ext4_htree_next_block(struct inode *dir, __u32 hash,
__u32 *start_hash);
static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
struct ext4_filename *fname,
- struct ext4_dir_entry_2 **res_dir);
+ struct ext4_dir_entry_2 **res_dir,
+ struct dx_frame *dx_frame);
static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname,
struct inode *dir, struct inode *inode);
@@ -380,6 +381,7 @@ static void ext4_dirent_csum_set(struct inode *inode,
(void *)t - (void *)dirent);
}
+
int ext4_handle_dirty_dirent_node(handle_t *handle,
struct inode *inode,
struct buffer_head *bh)
@@ -797,7 +799,7 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
dxtrace(printk("Look up %x", hash));
while (1) {
count = dx_get_count(entries);
- if (!count || count > dx_get_limit(entries)) {
+ if (count > dx_get_limit(entries)) {
ext4_warning_inode(dir,
"dx entry: count %u beyond limit %u",
count, dx_get_limit(entries));
@@ -866,6 +868,42 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
return ret_err;
}
+static void
+ext4_dx_delete_entry(handle_t *handle, struct inode *dir,
+ struct dx_frame *dx_frame, __le64 block)
+{
+ struct dx_entry *entries;
+ unsigned int count, limit;
+ int err, i;
+
+ entries = dx_frame->entries;
+ count = dx_get_count(entries);
+ limit = dx_get_limit(entries);
+
+ for (i = 0; i < count; i++)
+ if (entries[i].block == block)
+ break;
+
+ if (i >= count)
+ return;
+
+ err = ext4_journal_get_write_access(handle, dx_frame->bh);
+ if (err) {
+ ext4_std_error(dir->i_sb, err);
+ return;
+ }
+
+ for (; i < count - 1; i++)
+ entries[i] = entries[i + 1];
+
+ dx_set_count(entries, count - 1);
+ dx_set_limit(entries, limit);
+
+ err = ext4_handle_dirty_dx_node(handle, dir, dx_frame->bh);
+ if (err)
+ ext4_std_error(dir->i_sb, err);
+}
+
static void dx_release(struct dx_frame *frames)
{
struct dx_root_info *info;
@@ -1309,6 +1347,14 @@ int ext4_search_dir(struct buffer_head *bh, char *search_buf, int buf_size,
return 0;
}
+static int is_empty_dirent_block(struct inode *dir, struct buffer_head *bh)
+{
+ struct ext4_dir_entry_2 *de = (struct ext4_dir_entry_2 *)bh->b_data;
+
+ return (ext4_rec_len_from_disk(de->rec_len, dir->i_sb->s_blocksize)
+ == dir->i_sb->s_blocksize);
+}
+
static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block,
struct ext4_dir_entry *de)
{
@@ -1339,7 +1385,8 @@ static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block,
static struct buffer_head * ext4_find_entry (struct inode *dir,
const struct qstr *d_name,
struct ext4_dir_entry_2 **res_dir,
- int *inlined)
+ int *inlined,
+ struct dx_frame *dx_frame)
{
struct super_block *sb;
struct buffer_head *bh_use[NAMEI_RA_SIZE];
@@ -1388,7 +1435,7 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
goto restart;
}
if (is_dx(dir)) {
- ret = ext4_dx_find_entry(dir, &fname, res_dir);
+ ret = ext4_dx_find_entry(dir, &fname, res_dir, dx_frame);
/*
* On success, or if the error was file not found,
* return. Otherwise, fall back to doing a search the
@@ -1486,9 +1533,10 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
return ret;
}
-static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
- struct ext4_filename *fname,
- struct ext4_dir_entry_2 **res_dir)
+static struct buffer_head *ext4_dx_find_entry(
+ struct inode *dir, struct ext4_filename *fname,
+ struct ext4_dir_entry_2 **res_dir,
+ struct dx_frame *dx_frame)
{
struct super_block * sb = dir->i_sb;
struct dx_frame frames[EXT4_HTREE_LEVEL], *frame;
@@ -1502,6 +1550,10 @@ static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
frame = dx_probe(fname, dir, NULL, frames);
if (IS_ERR(frame))
return (struct buffer_head *) frame;
+ if (dx_frame) {
+ *dx_frame = *frame;
+ get_bh(dx_frame->bh);
+ }
do {
block = dx_get_block(frame->at);
bh = ext4_read_dirblock(dir, block, DIRENT);
@@ -1553,7 +1605,7 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
if (dentry->d_name.len > EXT4_NAME_LEN)
return ERR_PTR(-ENAMETOOLONG);
- bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
+ bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL, NULL);
if (IS_ERR(bh))
return (struct dentry *) bh;
inode = NULL;
@@ -1597,7 +1649,7 @@ struct dentry *ext4_get_parent(struct dentry *child)
struct ext4_dir_entry_2 * de;
struct buffer_head *bh;
- bh = ext4_find_entry(d_inode(child), &dotdot, &de, NULL);
+ bh = ext4_find_entry(d_inode(child), &dotdot, &de, NULL, NULL);
if (IS_ERR(bh))
return (struct dentry *) bh;
if (!bh)
@@ -2337,9 +2389,13 @@ int ext4_generic_delete_entry(handle_t *handle,
static int ext4_delete_entry(handle_t *handle,
struct inode *dir,
struct ext4_dir_entry_2 *de_del,
- struct buffer_head *bh)
+ struct buffer_head *bh,
+ struct dx_frame *dx_frame)
{
+ struct ext4_map_blocks map;
int err, csum_size = 0;
+ int should_truncate = 0;
+
if (ext4_has_inline_data(dir)) {
int has_inline_data = 1;
@@ -2363,11 +2419,35 @@ static int ext4_delete_entry(handle_t *handle,
if (err)
goto out;
+ if (dx_frame && dx_frame->bh && is_empty_dirent_block(dir, bh)) {
+
+ map.m_lblk = (dir->i_size - 1) >>
+ (dir->i_sb->s_blocksize_bits);
+ map.m_len = 1;
+ err = ext4_map_blocks(handle, dir, &map, 0);
+
+ if ((err > 0) && (bh->b_blocknr == map.m_pblk)) {
+ ext4_dx_delete_entry(handle, dir, dx_frame,
+ cpu_to_le64(map.m_lblk));
+ should_truncate = 1;
+ }
+ }
+
BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
+
err = ext4_handle_dirty_dirent_node(handle, dir, bh);
if (unlikely(err))
goto out;
+ if (should_truncate) {
+ dir->i_size -= dir->i_sb->s_blocksize;
+ ext4_truncate(dir);
+ if (dir->i_size == dir->i_sb->s_blocksize) {
+ ext4_clear_inode_flag(dir, EXT4_INODE_INDEX);
+ ext4_mark_inode_dirty(handle, dir);
+ }
+ }
+
return 0;
out:
if (err != -ENOENT)
@@ -2923,7 +3003,7 @@ static int ext4_rmdir(struct inode *dir, struct dentry *dentry)
return retval;
retval = -ENOENT;
- bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
+ bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL, NULL);
if (IS_ERR(bh))
return PTR_ERR(bh);
if (!bh)
@@ -2950,7 +3030,7 @@ static int ext4_rmdir(struct inode *dir, struct dentry *dentry)
if (IS_DIRSYNC(dir))
ext4_handle_sync(handle);
- retval = ext4_delete_entry(handle, dir, de, bh);
+ retval = ext4_delete_entry(handle, dir, de, bh, NULL);
if (retval)
goto end_rmdir;
if (!EXT4_DIR_LINK_EMPTY(inode))
@@ -2985,6 +3065,9 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
struct buffer_head *bh;
struct ext4_dir_entry_2 *de;
handle_t *handle = NULL;
+ struct dx_frame dx_frame;
+
+ memset(&dx_frame, 0, sizeof(dx_frame));
if (unlikely(ext4_forced_shutdown(EXT4_SB(dir->i_sb))))
return -EIO;
@@ -3000,7 +3083,7 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
return retval;
retval = -ENOENT;
- bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
+ bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL, &dx_frame);
if (IS_ERR(bh))
return PTR_ERR(bh);
if (!bh)
@@ -3028,9 +3111,10 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
dentry->d_name.len, dentry->d_name.name);
set_nlink(inode, 1);
}
- retval = ext4_delete_entry(handle, dir, de, bh);
+ retval = ext4_delete_entry(handle, dir, de, bh, &dx_frame);
if (retval)
goto end_unlink;
+
dir->i_ctime = dir->i_mtime = current_time(dir);
ext4_update_dx_flag(dir);
ext4_mark_inode_dirty(handle, dir);
@@ -3042,6 +3126,8 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
end_unlink:
brelse(bh);
+ if (dx_frame.bh)
+ brelse(dx_frame.bh);
if (handle)
ext4_journal_stop(handle);
trace_ext4_unlink_exit(dentry, retval);
@@ -3362,11 +3448,11 @@ static int ext4_find_delete_entry(handle_t *handle, struct inode *dir,
struct buffer_head *bh;
struct ext4_dir_entry_2 *de;
- bh = ext4_find_entry(dir, d_name, &de, NULL);
+ bh = ext4_find_entry(dir, d_name, &de, NULL, NULL);
if (IS_ERR(bh))
return PTR_ERR(bh);
if (bh) {
- retval = ext4_delete_entry(handle, dir, de, bh);
+ retval = ext4_delete_entry(handle, dir, de, bh, NULL);
brelse(bh);
}
return retval;
@@ -3390,7 +3476,8 @@ static void ext4_rename_delete(handle_t *handle, struct ext4_renament *ent,
retval = ext4_find_delete_entry(handle, ent->dir,
&ent->dentry->d_name);
} else {
- retval = ext4_delete_entry(handle, ent->dir, ent->de, ent->bh);
+ retval = ext4_delete_entry(handle, ent->dir, ent->de, ent->bh,
+ NULL);
if (retval == -ENOENT) {
retval = ext4_find_delete_entry(handle, ent->dir,
&ent->dentry->d_name);
@@ -3497,7 +3584,8 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
return retval;
}
- old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de, NULL);
+ old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de, NULL,
+ NULL);
if (IS_ERR(old.bh))
return PTR_ERR(old.bh);
/*
@@ -3511,7 +3599,7 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
goto end_rename;
new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
- &new.de, &new.inlined);
+ &new.de, &new.inlined, NULL);
if (IS_ERR(new.bh)) {
retval = PTR_ERR(new.bh);
new.bh = NULL;
@@ -3691,7 +3779,7 @@ static int ext4_cross_rename(struct inode *old_dir, struct dentry *old_dentry,
return retval;
old.bh = ext4_find_entry(old.dir, &old.dentry->d_name,
- &old.de, &old.inlined);
+ &old.de, &old.inlined, NULL);
if (IS_ERR(old.bh))
return PTR_ERR(old.bh);
/*
@@ -3705,7 +3793,7 @@ static int ext4_cross_rename(struct inode *old_dir, struct dentry *old_dentry,
goto end_rename;
new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
- &new.de, &new.inlined);
+ &new.de, &new.inlined, NULL);
if (IS_ERR(new.bh)) {
retval = PTR_ERR(new.bh);
new.bh = NULL;
--
2.20.1.321.g9e740568ce-goog
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