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GFS2: Only do one directory search on create 

Creation of a new inode requires a directory search in order to ensure
that we are not trying to create an inode with the same name as an
existing one. This was hidden away inside the create_ok() function.

In the case that there was an existing inode, and a lookup can be
substituted for a create (which is the case with regular files
when the O_EXCL flag is not in use) then we were doing a second
lookup in order to return the inode.

This patch merges these two lookups into one. This can be done by
passing a flag to gfs2_dir_search() to tell it to just return -EEXIST
in the cases where we don't actually want to look up the inode.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Steven Whitehouse 2013-06-11 13:45:29 +01:00
parent a9aefd707c
commit 5a00f3cc97
3 changed files with 26 additions and 29 deletions
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23
fs/gfs2/dir.c
View File

@ -1555,9 +1555,9 @@ out:
/**
* gfs2_dir_search - Search a directory
* @dip: The GFS2 inode
* @filename:
* @inode:
* @dip: The GFS2 dir inode
* @name: The name we are looking up
* @fail_on_exist: Fail if the name exists rather than looking it up
*
* This routine searches a directory for a file or another directory.
* Assumes a glock is held on dip.
@ -1565,22 +1565,25 @@ out:
* Returns: errno
*/
struct inode *gfs2_dir_search(struct inode *dir, const struct qstr *name)
struct inode *gfs2_dir_search(struct inode *dir, const struct qstr *name,
bool fail_on_exist)
{
struct buffer_head *bh;
struct gfs2_dirent *dent;
struct inode *inode;
u64 addr, formal_ino;
u16 dtype;
dent = gfs2_dirent_search(dir, name, gfs2_dirent_find, &bh);
if (dent) {
if (IS_ERR(dent))
return ERR_CAST(dent);
inode = gfs2_inode_lookup(dir->i_sb,
be16_to_cpu(dent->de_type),
be64_to_cpu(dent->de_inum.no_addr),
be64_to_cpu(dent->de_inum.no_formal_ino), 0);
dtype = be16_to_cpu(dent->de_type);
addr = be64_to_cpu(dent->de_inum.no_addr);
formal_ino = be64_to_cpu(dent->de_inum.no_formal_ino);
brelse(bh);
return inode;
if (fail_on_exist)
return ERR_PTR(-EEXIST);
return gfs2_inode_lookup(dir->i_sb, dtype, addr, formal_ino, 0);
}
return ERR_PTR(-ENOENT);
}

3
fs/gfs2/dir.h
View File

@ -18,7 +18,8 @@ struct gfs2_inode;
struct gfs2_inum;
extern struct inode *gfs2_dir_search(struct inode *dir,
const struct qstr *filename);
const struct qstr *filename,
bool fail_on_exist);
extern int gfs2_dir_check(struct inode *dir, const struct qstr *filename,
const struct gfs2_inode *ip);
extern int gfs2_dir_add(struct inode *inode, const struct qstr *filename,

29
fs/gfs2/inode.c
View File

@ -313,7 +313,7 @@ struct inode *gfs2_lookupi(struct inode *dir, const struct qstr *name,
goto out;
}
inode = gfs2_dir_search(dir, name);
inode = gfs2_dir_search(dir, name, false);
if (IS_ERR(inode))
error = PTR_ERR(inode);
out:
@ -346,17 +346,6 @@ static int create_ok(struct gfs2_inode *dip, const struct qstr *name,
if (!dip->i_inode.i_nlink)
return -ENOENT;
error = gfs2_dir_check(&dip->i_inode, name, NULL);
switch (error) {
case -ENOENT:
error = 0;
break;
case 0:
return -EEXIST;
default:
return error;
}
if (dip->i_entries == (u32)-1)
return -EFBIG;
if (S_ISDIR(mode) && dip->i_inode.i_nlink == (u32)-1)
@ -584,15 +573,19 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
goto fail;
error = create_ok(dip, name, mode);
if ((error == -EEXIST) && S_ISREG(mode) && !excl) {
inode = gfs2_lookupi(dir, &dentry->d_name, 0);
gfs2_glock_dq_uninit(ghs);
d_instantiate(dentry, inode);
return PTR_RET(inode);
}
if (error)
goto fail_gunlock;
inode = gfs2_dir_search(dir, &dentry->d_name, !S_ISREG(mode) || excl);
error = PTR_ERR(inode);
if (!IS_ERR(inode)) {
gfs2_glock_dq_uninit(ghs);
d_instantiate(dentry, inode);
return 0;
} else if (error != -ENOENT) {
goto fail_gunlock;
}
arq = error = gfs2_diradd_alloc_required(dir, name);
if (error < 0)
goto fail_gunlock;