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v9fs has been plagued by an over-complicated approach trying to map Linux dentry semantics to Plan 9 fid semantics. Our previous approach called for aggressive flushing of the dcache resulting in several problems (including wierd cwd behavior when running /bin/pwd). This patch dramatically simplifies our handling of this fid management. Fids will not be clunked as promptly, but the new approach is more functionally correct. We now clunk un-open fids only when their dentry ref_count reaches 0 (and d_delete is called). Another simplification is we no longer seek to match fids to the process-id or uid of the action initiator. The uid-matching will need to be revisited when we fix the security model. Signed-off-by: Eric Van Hensbergen <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,7 +1,7 @@ | ||
| /* | ||
| * V9FS FID Management | ||
| * | ||
| * Copyright (C) 2005 by Eric Van Hensbergen <[email protected]> | ||
| * Copyright (C) 2005, 2006 by Eric Van Hensbergen <[email protected]> | ||
| * | ||
| * This program is free software; you can redistribute it and/or modify | ||
| * it under the terms of the GNU General Public License as published by | ||
|
|
@@ -57,7 +57,6 @@ int v9fs_fid_insert(struct v9fs_fid *fid, struct dentry *dentry) | |
| } | ||
|
|
||
| fid->uid = current->uid; | ||
| fid->pid = current->pid; | ||
| list_add(&fid->list, fid_list); | ||
| return 0; | ||
| } | ||
|
|
@@ -88,7 +87,7 @@ struct v9fs_fid *v9fs_fid_create(struct v9fs_session_info *v9ses, int fid) | |
| new->rdir_fcall = NULL; | ||
| INIT_LIST_HEAD(&new->list); | ||
|
|
||
| return new; | ||
| return new; | ||
| } | ||
|
|
||
| /** | ||
|
|
@@ -103,76 +102,14 @@ void v9fs_fid_destroy(struct v9fs_fid *fid) | |
| kfree(fid); | ||
| } | ||
|
|
||
| /** | ||
| * v9fs_fid_walk_up - walks from the process current directory | ||
| * up to the specified dentry. | ||
| */ | ||
| static struct v9fs_fid *v9fs_fid_walk_up(struct dentry *dentry) | ||
| { | ||
| int fidnum, cfidnum, err; | ||
| struct v9fs_fid *cfid, *fid; | ||
| struct dentry *cde; | ||
| struct v9fs_session_info *v9ses; | ||
|
|
||
| v9ses = v9fs_inode2v9ses(current->fs->pwd->d_inode); | ||
| cfid = v9fs_fid_lookup(current->fs->pwd); | ||
| if (cfid == NULL) { | ||
| dprintk(DEBUG_ERROR, "process cwd doesn't have a fid\n"); | ||
| return ERR_PTR(-ENOENT); | ||
| } | ||
|
|
||
| cfidnum = cfid->fid; | ||
| cde = current->fs->pwd; | ||
| /* TODO: take advantage of multiwalk */ | ||
|
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||
| fidnum = v9fs_get_idpool(&v9ses->fidpool); | ||
| if (fidnum < 0) { | ||
| dprintk(DEBUG_ERROR, "could not get a new fid num\n"); | ||
| err = -ENOENT; | ||
| goto clunk_fid; | ||
| } | ||
|
|
||
| while (cde != dentry) { | ||
| if (cde == cde->d_parent) { | ||
| dprintk(DEBUG_ERROR, "can't find dentry\n"); | ||
| err = -ENOENT; | ||
| goto clunk_fid; | ||
| } | ||
|
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||
| err = v9fs_t_walk(v9ses, cfidnum, fidnum, "..", NULL); | ||
| if (err < 0) { | ||
| dprintk(DEBUG_ERROR, "problem walking to parent\n"); | ||
| goto clunk_fid; | ||
| } | ||
|
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||
| cfidnum = fidnum; | ||
| cde = cde->d_parent; | ||
| } | ||
|
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||
| fid = v9fs_fid_create(v9ses, fidnum); | ||
| if (fid) { | ||
| err = v9fs_fid_insert(fid, dentry); | ||
| if (err < 0) { | ||
| kfree(fid); | ||
| goto clunk_fid; | ||
| } | ||
| } | ||
|
|
||
| return fid; | ||
|
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||
| clunk_fid: | ||
| v9fs_t_clunk(v9ses, fidnum); | ||
| return ERR_PTR(err); | ||
| } | ||
|
|
||
| /** | ||
| * v9fs_fid_lookup - retrieve the right fid from a particular dentry | ||
| * @dentry: dentry to look for fid in | ||
| * @type: intent of lookup (operation or traversal) | ||
| * | ||
| * search list of fids associated with a dentry for a fid with a matching | ||
| * thread id or uid. If that fails, look up the dentry's parents to see if you | ||
| * can find a matching fid. | ||
| * find a fid in the dentry | ||
| * | ||
| * TODO: only match fids that have the same uid as current user | ||
| * | ||
| */ | ||
|
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||
|
|
@@ -187,26 +124,7 @@ struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry) | |
| return_fid = list_entry(fid_list->next, struct v9fs_fid, list); | ||
|
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||
| if (!return_fid) { | ||
| struct dentry *par = current->fs->pwd->d_parent; | ||
| int count = 1; | ||
| while (par != NULL) { | ||
| if (par == dentry) | ||
| break; | ||
| count++; | ||
| if (par == par->d_parent) { | ||
| dprintk(DEBUG_ERROR, | ||
| "got to root without finding dentry\n"); | ||
| break; | ||
| } | ||
| par = par->d_parent; | ||
| } | ||
|
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| /* XXX - there may be some duplication we can get rid of */ | ||
| if (par == dentry) { | ||
| return_fid = v9fs_fid_walk_up(dentry); | ||
| if (IS_ERR(return_fid)) | ||
| return_fid = NULL; | ||
| } | ||
| dprintk(DEBUG_ERROR, "Couldn't find a fid in dentry\n"); | ||
| } | ||
|
|
||
| return return_fid; | ||
|
|
||
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