[PATCH] Clean up expand_fdtable() and expand_files()
Perform a code cleanup against the expand_fdtable() and expand_files() functions inside fs/file.c. It aims to make the flow of code within these functions simpler and easier to understand, via added comments and modest refactoring. Signed-off-by: Vadim Lobanov <vlobanov@speakeasy.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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76
fs/file.c
76
fs/file.c
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@ -288,71 +288,65 @@ out:
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}
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/*
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* Expands the file descriptor table - it will allocate a new fdtable and
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* both fd array and fdset. It is expected to be called with the
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* files_lock held.
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* Expand the file descriptor table.
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* This function will allocate a new fdtable and both fd array and fdset, of
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* the given size.
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* Return <0 error code on error; 1 on successful completion.
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* The files->file_lock should be held on entry, and will be held on exit.
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*/
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static int expand_fdtable(struct files_struct *files, int nr)
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__releases(files->file_lock)
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__acquires(files->file_lock)
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{
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int error = 0;
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struct fdtable *fdt;
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struct fdtable *nfdt = NULL;
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struct fdtable *new_fdt, *cur_fdt;
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spin_unlock(&files->file_lock);
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nfdt = alloc_fdtable(nr);
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if (!nfdt) {
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error = -ENOMEM;
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spin_lock(&files->file_lock);
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goto out;
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}
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new_fdt = alloc_fdtable(nr);
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spin_lock(&files->file_lock);
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fdt = files_fdtable(files);
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if (!new_fdt)
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return -ENOMEM;
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/*
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* Check again since another task may have expanded the
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* fd table while we dropped the lock
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* Check again since another task may have expanded the fd table while
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* we dropped the lock
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*/
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if (nr >= fdt->max_fds || nr >= fdt->max_fdset) {
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copy_fdtable(nfdt, fdt);
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cur_fdt = files_fdtable(files);
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if (nr >= cur_fdt->max_fds || nr >= cur_fdt->max_fdset) {
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/* Continue as planned */
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copy_fdtable(new_fdt, cur_fdt);
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rcu_assign_pointer(files->fdt, new_fdt);
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free_fdtable(cur_fdt);
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} else {
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/* Somebody expanded while we dropped file_lock */
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/* Somebody else expanded, so undo our attempt */
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spin_unlock(&files->file_lock);
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__free_fdtable(nfdt);
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__free_fdtable(new_fdt);
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spin_lock(&files->file_lock);
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goto out;
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}
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rcu_assign_pointer(files->fdt, nfdt);
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free_fdtable(fdt);
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out:
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return error;
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return 1;
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}
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/*
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* Expand files.
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* Return <0 on error; 0 nothing done; 1 files expanded, we may have blocked.
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* Should be called with the files->file_lock spinlock held for write.
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* This function will expand the file structures, if the requested size exceeds
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* the current capacity and there is room for expansion.
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* Return <0 error code on error; 0 when nothing done; 1 when files were
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* expanded and execution may have blocked.
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* The files->file_lock should be held on entry, and will be held on exit.
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*/
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int expand_files(struct files_struct *files, int nr)
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{
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int err, expand = 0;
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struct fdtable *fdt;
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fdt = files_fdtable(files);
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if (nr >= fdt->max_fdset || nr >= fdt->max_fds) {
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if (fdt->max_fdset >= NR_OPEN ||
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fdt->max_fds >= NR_OPEN || nr >= NR_OPEN) {
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err = -EMFILE;
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goto out;
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}
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expand = 1;
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if ((err = expand_fdtable(files, nr)))
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goto out;
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}
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err = expand;
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out:
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return err;
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/* Do we need to expand? */
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if (nr < fdt->max_fdset && nr < fdt->max_fds)
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return 0;
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/* Can we expand? */
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if (fdt->max_fdset >= NR_OPEN || fdt->max_fds >= NR_OPEN ||
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nr >= NR_OPEN)
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return -EMFILE;
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/* All good, so we try */
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return expand_fdtable(files, nr);
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}
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static void __devinit fdtable_defer_list_init(int cpu)
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