commit b20746efc52bed7f8dcfcb40e755f33c5f1d1592
Author: Rachita Kothiyal <[EMAIL PROTECTED]>
Date: Thu Mar 27 01:42:38 2008 -0400
Unionfs ODF: use first writable branch (fix/cleanup)
Cleanup code in ->create, ->symlink, and ->mknod: refactor common code into
helper functions. Also, this allows writing to multiple branches again,
which was broken by an earlier patch.
Signed-off-by: Erez Zadok <[EMAIL PROTECTED]
diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
index b292f88..9abc39c 100644
--- a/fs/unionfs/inode.c
+++ b/fs/unionfs/inode.c
@@ -18,13 +18,94 @@
#include "union.h"
+/*
+ * Find a writeable branch to create new object in. Checks all writeble
+ * branches of the parent inode, from istart to iend order; if none are
+ * suitable, also tries branch 0 (which may require a copyup).
+ *
+ * Return a lower_dentry we can use to create object in, or ERR_PTR.
+ */
+static struct dentry *find_writeable_branch(struct inode *parent,
+ struct dentry *dentry)
+{
+ int err = -EINVAL;
+ int bindex, istart, iend;
+ struct dentry *lower_dentry = NULL;
+
+ istart = ibstart(parent);
+ iend = ibend(parent);
+ if (istart < 0)
+ goto out;
+
+begin:
+ for (bindex = istart; bindex <= iend; bindex++) {
+ /* skip non-writeable branches */
+ err = is_robranch_super(dentry->d_sb, bindex);
+ if (err) {
+ err = -EROFS;
+ continue;
+ }
+ lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (!lower_dentry)
+ continue;
+ if (lower_dentry->d_inode && UNIONFS_D(dentry)->odf.whiteout)
+ /*
+ * This file logically does not exist. Delete the lower
+ * file and make way for the new creation here
+ */
+ err = unionfs_force_rm(dentry, &lower_dentry, bindex);
+
+ /*
+ * we have either found the right branch to create this
+ * dentry in, or we are bailing out with an error, which
+ * will be handled outside this loop
+ */
+ break;
+ }
+ /*
+ * If istart wasn't already branch 0, and we got any error, then try
+ * branch 0 (which may require copyup)
+ */
+ if (err && istart > 0) {
+ istart = 0;
+ iend = 0;
+ goto begin;
+ }
+
+ /*
+ * If we tried even branch 0, and still got an error, abort. But if
+ * the error was an EROFS, then we should try to copyup.
+ */
+ if (err && err != -EROFS)
+ goto out;
+
+ /*
+ * If we get here, then check if copyup needed. If lower_dentry is
+ * NULL, create the entire dentry directory structure in branch 0.
+ */
+ if (!lower_dentry) {
+ bindex = 0;
+ lower_dentry = create_parents(parent, dentry,
+ dentry->d_name.name, bindex);
+ if (IS_ERR(lower_dentry)) {
+ err = PTR_ERR(lower_dentry);
+ goto out;
+ }
+ }
+ err = 0; /* all's well */
+out:
+ if (err)
+ return ERR_PTR(err);
+ return lower_dentry;
+}
+
+
static int unionfs_create(struct inode *parent, struct dentry *dentry,
int mode, struct nameidata *nd)
{
int err = 0;
struct dentry *lower_dentry = NULL;
struct dentry *lower_parent_dentry = NULL;
- int bstart;
int valid = 0;
struct nameidata lower_nd;
@@ -45,47 +126,12 @@ static int unionfs_create(struct inode *parent, struct
dentry *dentry,
*/
BUG_ON(!valid && dentry->d_inode);
- /*
- * We shouldn't create things in a read-only branch; this check is a
- * bit redundant as we don't allow branch 0 to be read-only at the
- * moment
- */
- err = is_robranch_super(dentry->d_sb, 0);
- if (err) {
- err = -EROFS;
+ lower_dentry = find_writeable_branch(parent, dentry);
+ if (IS_ERR(lower_dentry)) {
+ err = PTR_ERR(lower_dentry);
goto out;
}
- /*
- * We _always_ create on branch 0
- */
- bstart = 0;
-
- lower_dentry = unionfs_lower_dentry_idx(dentry, bstart);
- if (!lower_dentry) {
- /*
- * if lower_dentry is NULL, create the entire
- * dentry directory structure in branch 'bindex'.
- * lower_dentry will NOT be null when bindex == bstart
- * because lookup passed as a negative unionfs dentry
- * pointing to a lone negative underlying dentry
- */
- lower_dentry = create_parents(parent, dentry,
- dentry->d_name.name,
- bstart);
- if (!lower_dentry || IS_ERR(lower_dentry)) {
- if (IS_ERR(lower_dentry))
- err = PTR_ERR(lower_dentry);
- goto out;
- }
- unionfs_postcopyup_setmnt(dentry->d_parent);
- }
-
- if (lower_dentry->d_inode && UNIONFS_D(dentry)->odf.whiteout) {
- err = unionfs_force_rm(dentry, &lower_dentry, bstart);
- if (err)
- goto out;
- }
lower_parent_dentry = lock_parent(lower_dentry);
if (IS_ERR(lower_parent_dentry)) {
err = PTR_ERR(lower_parent_dentry);
@@ -101,7 +147,6 @@ static int unionfs_create(struct inode *parent, struct
dentry *dentry,
if (err || !lower_dentry->d_inode)
unlock_dir(lower_parent_dentry);
-
else {
err = odf_lookup(dentry->d_parent, dentry,
ODF_LOOKUP_FILE|ODF_LOOKUP_RMV_WH);
@@ -353,7 +398,6 @@ static int unionfs_symlink(struct inode *dir, struct dentry
*dentry,
struct dentry *lower_dentry = NULL;
struct dentry *lower_dir_dentry = NULL;
umode_t mode;
- int bstart;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
@@ -364,48 +408,17 @@ static int unionfs_symlink(struct inode *dir, struct
dentry *dentry,
goto out;
}
- /* We create in the leftmost branch. */
- bstart = 0;
-
- lower_dentry = unionfs_lower_dentry_idx(dentry, bstart);
- if (!lower_dentry) {
- /*
- * if lower_dentry is NULL, create the entire
- * dentry directory structure in branch 'bindex'.
- * lower_dentry will NOT be null when bindex ==
- * bstart because lookup passed as a negative
- * unionfs dentry pointing to a lone negative
- * underlying dentry
- */
- lower_dentry = create_parents(dir, dentry,
- dentry->d_name.name,
- bstart);
- if (!lower_dentry || IS_ERR(lower_dentry)) {
- if (IS_ERR(lower_dentry))
- err = PTR_ERR(lower_dentry);
-
- printk(KERN_ERR "unionfs: lower dentry "
- "NULL (or error) for bindex = %d\n",
- bstart);
- goto out;
- }
- unionfs_postcopyup_setmnt(dentry->d_parent);
- }
-
- if (lower_dentry->d_inode && UNIONFS_D(dentry)->odf.whiteout) {
- err = unionfs_force_rm(dentry, &lower_dentry, bstart);
- if (err)
- goto out;
+ lower_dentry = find_writeable_branch(dir, dentry);
+ if (IS_ERR(lower_dentry)) {
+ err = PTR_ERR(lower_dentry);
+ goto out;
}
lower_dir_dentry = lock_parent(lower_dentry);
- err = is_robranch_super(dentry->d_sb, bstart);
- if (!err) {
- mode = S_IALLUGO;
- err = vfs_symlink(lower_dir_dentry->d_inode,
- lower_dentry, symname, mode);
- }
+ mode = S_IALLUGO;
+ err = vfs_symlink(lower_dir_dentry->d_inode,
+ lower_dentry, symname, mode);
unlock_dir(lower_dir_dentry);
if (!(err || !lower_dentry->d_inode)) {
@@ -562,7 +575,6 @@ static int unionfs_mknod(struct inode *dir, struct dentry
*dentry, int mode,
int err = 0;
struct dentry *lower_dentry = NULL;
struct dentry *lower_parent_dentry = NULL;
- int bstart;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
@@ -573,29 +585,10 @@ static int unionfs_mknod(struct inode *dir, struct dentry
*dentry, int mode,
goto out;
}
- bstart = 0;
-
- if (is_robranch_super(dentry->d_sb, bstart))
+ lower_dentry = find_writeable_branch(dir, dentry);
+ if (IS_ERR(lower_dentry)) {
+ err = PTR_ERR(lower_dentry);
goto out;
-
- lower_dentry = unionfs_lower_dentry_idx(dentry, bstart);
- if (!lower_dentry) {
- lower_dentry = create_parents(dir, dentry,
- dentry->d_name.name,
- bstart);
- if (IS_ERR(lower_dentry)) {
- printk(KERN_ERR "unionfs: failed to create "
- "parents on %d, err = %ld\n",
- bstart, PTR_ERR(lower_dentry));
- goto out;
- }
- unionfs_postcopyup_setmnt(dentry->d_parent);
- }
-
- if (lower_dentry->d_inode && UNIONFS_D(dentry)->odf.whiteout) {
- err = unionfs_force_rm(dentry, &lower_dentry, bstart);
- if (err)
- goto out;
}
lower_parent_dentry = lock_parent(lower_dentry);
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